How to care for a living Christmas tree
By Richard Hentschel, Illinois Extension Horticulture Educator
Those thinking green this holiday season may want to skip the tree lot and consider buying a living evergreen to plant outside after Christmas.
Buying the tree is the easiest part. Caring for it to ensure the tree lasts for years to come is a little more complicated.
Live evergreen trees can be purchased from nurseries either with the roots and soil balled and burlapped, also known as B&B, or in a container. B&B trees will be heavier and a little more awkward to handle than a container-grown tree which uses a light soil mix.
Unlike cut trees, living trees should remain outside until just before Christmas to keep it dormant. Find a shady location or store it on the north side of a building away from direct sunlight.
This is also a good time to pick a roomy spot for the tree’s permanent home. Evergreen branches will be at least 12 to 15 feet wide at the base and unless it’s smaller stature variety, trees can easily be at least 35 feet tall. Layer one or two bales of straw 6 to 8 inches deep over the site to keep the soil from freezing deeply.
Timing for moving the tree indoors and then planting it outdoors is critical.
Trees should only be inside for four to five days total. Otherwise, they may begin to break their winter dormancy and actually start to grow indoors.
Keeping the tree’s root ball or container moist before it is planted is important.
Container-grown trees have very efficient drainage and should be checked daily to make sure that the soil is moist. Place a large saucer underneath the container and water the tree evenly and just enough so a little water collects in the saucer.
B&B plants have heavier soil, which holds more moisture but needs more preparation. Use a large watertight container, such as a reusable plastic tub or large pot, filled with moist potting soil or shredded peat moss to support and insulate the root ball.
Once inside where the air is drier, check moisture levels daily.
If the living tree is shorter than a typical cut tree, consider elevating it on a stable structure, such as cement blocks. The tree is out of reach of pets and there is more room underneath for presents.
When the tree is ready to be planted, move the straw and dig a shallow hole that is at least 12 inches wider than the ball or container to give the roots room. Remove the burlap or container and any rope or twine. The root flare, where the base of the trunk starts to flare out, should be at ground level or slightly higher.
Water the newly planted tree well and use the straw to mulch it, which will slow the ground from freezing and allow the roots to acclimate.
When spring comes, plan on watering it regularly to supplement the rain as needed, especially during dry summer months.
Grow a living Christmas tree with Norfolk Island Pine
By Ken Johnson, Illinois Extension Horticulture Educator
Miniature living evergreen trees, often decked out with bells and bows, are a common decoration or gift during the holidays. With proper care these Norfolk Island pine trees can last for years as beautiful houseplants.
Despite their name, these evergreens are not actually pine trees. Instead, they belong to the ancient plant family Araucariaceae, which were widespread during the Jurassic and Cretaceous periods but are now confined to the southern hemisphere.
In their native habitat on Norfolk Island, which is in the South Pacific, these evergreens can reach heights of up to 200 feet and have trunks up to 10 feet in diameter. European explorer James Cook arrived at the island in 1774. With the trees’ long, straight trunks, Cook believed the island’s evergreens could be used to make ship masts.
Ever since, Norfolk Island pines have been transported around the world. They can be found growing in humid coastal areas in many countries, including the U.S.
In addition to being used as an ornamental plant, their wood is used for construction, woodturning, and crafts.
As houseplants, Norfolk Island pines grow slowly, about 3 to 6 inches a year and they typically will reach heights of 6 to 8 feet, although they can grow taller.
The key to maintaining any healthy houseplant is to mimic its native environment as closely as possible.
Homes tend to be dry, especially in winter, so it is important to take steps to increase the humidity around plants. This can be done by misting plants, using a humidifier, or making a humid microclimate.
Fill a saucer with rocks and add water until the rocks are slightly above the water line; then place the plant on top of the rocks. While Norfolk Island pines like moist conditions, if the plant is overwatered or has wet feet it can lose branches. Allow the soil to dry between waterings and make sure the pot has drainage holes.
A diluted liquid houseplant fertilizer can be used every two weeks while they are actively growing, typically from March to September.
Norfolk Island pines enjoy bright locations, but they can tolerate lower light conditions once they have been acclimated. If plants are not allowed to acclimate, entire branches may yellow and die. In low light conditions, branches become long and droopy, and growth will slow. Turn the plant occasionally so it receives adequate light and grows evenly and straight.
With proper care, a holiday Norfolk Pine tree will last for years to come.
Picking the perfect Christmas tree starts at home
By Ron Wolford, Illinois Extension horticulture educator
From pre-lit artificial trees to potted living evergreens, the holidays have more tree options than ever, but for some only a visit to the tree lot or farm will do.
Visiting a Christmas tree farm, garden center, or pop-up lot and choosing a real tree is a family tradition for many. Keeping that tree fresh throughout the holiday season is a lot easier with some pre-visit planning.
The first step is to find the perfect spot. Pick a location away from heat sources, such as spaces heaters, fireplaces, TVs, radiators and air vents to avoid drying out the tree and creating a safety hazard.
Next, measure the height and width of the space in the room where the tree will be placed. There is nothing worse than bringing a tree indoors only to find it's too tall. Take a tape measure with you to the farm or the tree lot.
If the tree will be displayed in front of a large window, choose one that looks as good as possible from all angles. If the tree is against a wall, a tree with three good sides is a great option, while a tree with two good sides would work well in a corner.
Keep in mind, the more picture-perfect a tree is, the more expensive it will be.
When choosing a tree, look for a healthy green specimen with few browning needles. The needles should be flexible and not fall off easily. Raise the tree a few inches off the ground and drop it on the trunk end. It is normal for a few inner brown needles to fall, but very few green needles should drop off the tree.
Make sure the trunk or base of the tree is straight and long enough so that it will fit easily into the stand after making additional trunk cuts. When buying a tree from a retail lot, Wolford recommends going during the day to get a better view.
If you’re not putting it up right away, store the tree in an unheated garage or some other area out of the wind. Make a fresh 1-inch cut on the end and place the tree in a bucket of warm water.
Before moving the tree indoors, check for any bird nests or insect egg masses. Cut another 1-inch slice off the stump and place the tree in a sturdy stand with water. Commercially prepared mixes, sugar, aspirin, or other water additives are not necessary. Research has shown that plain water will keep a tree fresh.
The stand’s water reservoir should provide one quart of water for every inch of trunk diameter. Keep the water level several inches above the cut. If the base dries out, resin will cover the cut preventing the tree from absorbing water.
After the holidays, consider rehoming the tree. Many communities offer a recycling program with trees going on to provide habitat for wildlife, enrichment for zoo animals or to create erosion barriers.
For more information about trees selection and care, visit go.illinois.edu/ChristmasTreeCare.
Perennial plant of the year Calamint a perfect pick for pollinators
By Martha Smith, University of Illinois Horticulture Educator
As constant as the New Year’s Eve ball drop in New York City, every year the Perennial Plant Association presents its plant of the year. Its 2021 choice is calamint, a sun-loving, low-growing bushy perennial with long-lasting blooms that benefit pollinators.
Since 1990, Perennial Plant Association members have voted for a standout perennial to showcase annually. These plants are always low maintenance with multiple-season interest and are suitable for a wide range of growing climates according to the association.
Calamint, Calamintha nepeta subsp. Nepeta, is a member of the mint family and is an excellent companion for an herb garden, does great in containers and is lovely cascading over low retaining walls
It is low maintenance, undemanding and dependable and is the perfect companion for other summer bloomers and foliage.
With tiny white flowers sometimes touched with pale blue from early summer until frost, calamint supports bees, butterflies and other pollinators while its aromatic foliage is deer resistant.
Native from southern Europe to Great Britain, calamint prefers full sun and will tolerate partial afternoon shade. It does best in soils with good drainage but once established it can be drought tolerant. Plants grow up to 2 feet tall and 2 feet wide and work well as an edge planting.
It is a favorite in stylized meadows, matrix plantings and other modern perennial designs. Gardeners can also create a lovely monochromatic garden with past plants of the year such as Anemone xhybrida ‘Honorine Jobert’ and Phlox paniculata ‘David’, or complemented with ornamental grasses such as switchgrass, Panicum virgatum ‘Northwind’, or little bluestem, Schyzacharium scoparium.
Gardeners may have noticed that the scientific name of calamint refers to a sub-species, subsp., instead of a plant variety, var. The difference is a matter of taxonomic semantics. The two terms are interchangeable according to the International Association for Plant Taxonomy. Much like the metric vs. imperial systems of measurement, European plant taxonomists use subspecies while North American taxonomists prefer variety.
Calamint is easily started from seed. It may spread in the garden by rhizomes or self-seeding to form an interesting ground cover. Stems touching the ground may root at the nodes.
Shear or cut back plants after flowering to tidy the planting, to remove unsightly foliage or to prevent any unwanted self-seeding.
To see calamint in its full glory, visit Lurie Garden in Chicago where it is planted in several areas.
Blooming plant ideas for Valentine’s Day
By Brittnay Haag, Horticulture Educator, Illinois Extension
The tradition of giving flowers to family and friends to express affection on Valentines’ Day began centuries ago. Give your loved one a gift this year with blooms that can be enjoyed long after February 14.
Blooming houseplants are great alternatives to traditional bouquets of cut flowers. With a little care and maintenance, these plants can thrive in your house or office and rebloom multiple times.
This waxy leafed succulent is low maintenance and has colorful blooms. Kalanchoe flowers can be red, pink, yellow or white. Cut off the blooms once they are faded to encourage new buds to form. The soil should dry out between watering, as this plant can be easily overwatered.
Kalanchoe grows best in bright, indirect sunlight and may get leggy in low light conditions. It can also be easily propagated by stem or leaf cuttings to create new plants. Place the plant outside in the summer to grow and bring them inside before the first frost. They will develop flower buds in response to the long nights of fall.
These heart-shaped leaved plants have unique foliage and showstopper flowers that can bloom for four to six weeks. Flowers can be a variety of shades of red, pink and white. Water cyclamens at the base of the plant when it dries out, soaking the soil until water flows out the bottom drainage holes. Cyclamens grow best in bright, indirect sunlight and thrive in cooler temperatures, 55°F to 60°F.
Cyclamens will go dormant after they bloom with foliage yellowing and dying down to the soil. Remove the dried foliage and place the container in a cool, dark place for two months. After the dormancy period, resume watering and add cyclamen bulbs to a new container of soil and place it in bright, indirect light. New foliage should start growing soon with blooms following a couple of months after.
Instead of an arrangement of cut roses that will die after a week, give someone the whole plant. Delicate miniature rose buds can be found in red, pink, or white and can be deadheaded to encourage new blooms. When grown indoors, roses need bright sunlight in a south-facing window and constant temperatures ranging from 60°F to 75°F. Lightly mist the foliage daily to maintain humidity levels.
They can be planted outdoors in a container or the ground in the summer but bring them inside before the first frost. Most miniature roses will go dormant in the winter and begin to grow again in the spring.
Many orchid species grow well indoors. Phalaenopsis are commonly found in stores and the easiest to care for. While orchids can be a challenge to rebloom, they will if placed in a window with bright, indirect light.
Orchids also need a good source of humidity. They do well in the kitchen, a bathroom or on a tray of gravel and water. Water orchids weekly with collected rainwater or distilled water until water flows out the drainage holes and fills the tray below. Allow it to dry out between watering. Mist the plant frequently to maintain the surrounding humidity levels.
Or, if you are looking for something a little more unique, give a potted Venus flytrap, sensitive plant, air plant, or succulent.
Visit Illinois Extension's website at extension.illinois.edu/global/horticulture for more information about houseplant care and maintenance.
How to create a fruit garden
By Bruce Black, Horticulture Educator, Illinois Extension
Winter is a time for togetherness and rest before spring. It’s also a great time to look ahead and make plans for new garden ventures.
A perennial fruit garden is a great project with years of benefits. Proper planning and set up can give home gardeners decades worth of fresh produce.
Begin by looking at the landscape and deciding if and how much space there is for new additions. Tree fruit such as apples, peaches, and cherries need more space than small fruits such as kiwifruit, strawberries, blackberries, and blueberries. Those with limited space can consider container fruits.
Next, consider the site. Fruit plantings prefer a full-sun fertile location. Planting in an elevated or sloped site helps with water drainage and air circulation. A windbreak helps tree fruits in the winter and keeping out of low laying areas helps to avoid frost pockets.
Make sure to pick a convenient location close to a water source. If it is out of sight, gardeners may not prioritize its maintenance or prefer not to walk to a distant site in the heat of the summer.
Doing a soil test provides a baseline of nutrients and pH and amendments can made as needed for fruit crop varieties.
Avoid areas that may have had Verticillium wilt, a soilborne fungus that can affect more than 300 plant species. Verticillium wilt reduces fruit yields, causes wilting, stunting and killing of plants. Plants may be infected for awhile before symptoms are visible. Try not to plant in areas planted with in the last three to five years with tomatoes, potatoes, peppers, melons, okra, beats or roses.
The final step of planning your fruit garden, is selecting plants. Cultivars should be adapted for USDA zone 5 or colder for Northern Illinois and zone 6 or colder for Southern Illinois. Look at local garden centers, nurseries, and national fruit stock retailers for cultivars and necessary cross-pollinator cultivars.
While researching and planning, feel free to contact the University of Illinois Extension office in your county with any questions. Master Gardener volunteers and Extension staff are happy to provide guidance and recommendations.
For more information on fruit garden planting, check out Illinois Extension’s Small Fruit Crops for the Backyard website at web.extension.illinois.edu/fruit/index.cfm for fruit specific information and cultivar recommendations.
Preventing fruit tree diseases starts in the dormant season
By Andrew Holsinger, Horticulture Educator, Illinois Extension
Winter is a great time for orchard owners and fruit tree gardeners to reflect on how their trees are doing and to create a plan for the coming growing season.
When it comes to disease possibilities, tracking seasonal successes and failures helps in the long term.
Keeping a journal of activities of management and care is essential in caring for fruit trees. Using a spray guide provides a reference based on the disease and physiological state of the tree.
The most effective way to care for tree fruit diseases is for both commercial and homeowner level gardeners to know when to spray fungicides and herbicides. Often, a tree is infected long before symptoms are observed and prevention is key to tree health, especially with fungal diseases. Fungicide needs to be applied and reapplied to keep trees protected throughout the season.
Some sprays can only be applied in late winter and early spring to prevent disease before the leaves have emerged. Diseases often develop because a spray wasn’t applied.
Peach leaf curl is an example of a disease that can easily be avoided by spraying during the dormant season.
Fruit tree disease prevent starts early by choosing disease resistant varieties. Only plant top quality, healthy nursery stock to avoid failure. Trees that are stressed are more susceptible to disease and insect pressures. Controlling insects and other pests is important because any wound on trees or fruit is a possible entry point for pathogens.
These apple varieties have disease resistant characteristics and are good options for Illinois landscapes or orchards: Crimson Crisp, Dayton, Enterprise, Freedom, Golden Delicious, Gold Rush, Jonafree, Liberty, Priscilla and William’s Pride.
Also consider dwarf or semi-dwarf trees which are smaller and more easily manageable when it comes to disease control and fruit production.
Good tree sanitation is also important in preventing disease. Inspect trees for mummies, which are unpicked, withered and infected fruits that carry spores that can cause problems during the next season. Cleaning up fallen leaves and fruits after the harvest is a good practice to reduce the number of fungal spores, especially for apple scab, for next year.
Pruning is probably the most neglected aspect of disease control. Pruning allows for more air circulation, light penetration and more adequate spray coverage.
Winter pruning boosts blackberry and raspberry harvests
By Kelly Allsup, Horticulture Educator, Illinois Extension
As a child, my grandparents would send my sisters and I to the unmanaged portions of their property to pick blackberries. The plants were a gangly massive mess of thorns that produced a minimal amount of fruit. Most of the time we brought enough for grandma to make a pie with probably just as much of the sun sweetened fruits in our bellies.
Although, this was a tactic to get the grandkids out of the house, imagine if these wild berries had been pruned in late winter? We might have brought back enough for 10 pies.
Pruning backyard brambles in late winter not only increases production of fruits but also aids in disease prevention throughout the growing season.
Bushes have different pruning needs depending on their attributes. Everbearing plants need to be trimmed in late winter erect brambles need pruning in summer as well. To make pruning less intimidating, gardeners should identify the cultivar to make a plant specific plan before bringing out the loppers.
Primocanes vs. Floricanes
Blackberry and raspberry bush canes, the bramble’s stems, are a mix of primocanes and floricanes. Primocanes are vibrant green new-growth canes. These canes are not ready to produce flowers or fruit, except for fall-bearing brambles.
Floricanes are older, overwintered canes that produce flowers and fruit and can be productive for up to 20 years. These dark red stems are covered in a white bloom, which rubs off and is used by the plant as a sunscreen.
Without pruning or cutting back canes, the bush produces less fruit and can harbor disease and pests. Old fruiting structures on the plant indicate that the cane is a floricane that should be removed.
For example, on a semi-erect blackberry ‘Chester Thornless’ remove floricanes, and diseased canes until there are only six to eight of the strongest primocanes. On these branches, cut back the tip of the stem to 5 feet. The primocanes will have lateral branches that should be pruned to 18 to 24 inches long.
If pruning a thorned variety, wear gloves and long sleeves.
Roots suckering vs. hills
Root Suckering: Brambles such as yellow raspberries, erect blackberries, and the red raspberry ‘Lauren’ spread by root suckers, creating a hedge row. They are thinned by cutting canes to the ground, leaving 6 inches between canes and removing any canes outside of the row.
Hills: Brambles such as black raspberries and semi-erect blackberries do not spread by suckers and retain their individual plant-form in a “hill.” For pruning, last year’s floricanes are removed and the primocanes are headed back.
Everbearing vs. Biennial canes
Most brambles produce on biennial canes, but some are everbearing, which means it can bear fruit until the fall. Brambles such as yellow raspberry ‘Anne’ are everbearing.
If the primocanes that bore fruit in fall are left to overwinter, they will fruit again, lower on the cane in late spring and then die. By mowing down all the canes in late winter, you sacrifice the first harvest to have a more abundant harvest in the fall.
Erect and Semi-erect
Erect brambles produce stiff, upright canes that need summer and winter pruning. The erect growth habit is common in both raspberries and blackberries. These tend to not need a trellising system.
Semi-erect brambles produce thick, arching canes that benefit from winter pruning. These varieties will start growing upright and bend over to trail along the ground if not supported. Growth habit determines the type of trellis support canes require. Black raspberries tend to be semi-erect and if not pruned adequately the tips of branches will touch the ground and begin to root, limiting fruit production. The Refuge Food Forest in Normal, Ill., where I live grows black raspberry ‘Bristol’ that must be tipped during the summer or the mowers will have issues between the rows.
Pruning at Spring Planting
New plants should also be pruned to the ground when they are planted in early spring. If looking for cultivar recommendations for Illinois, visit Small Fruit Crops for the Backyard.
Most plants purchased online will come bare rooted and should be soaked in water at least 30 minutes before planting. Plants from nurseries or greenhouses may come potted up and will not require soaking
Plant new brambles 4 to 6 feet apart in a hedgerow when the soil is not wet. Hedgerows should be 10 to 12 feet apart for Illinois semi-erect varieties.
Dig a hole one and a half times wider than the root system and fan out the roots. Water immediately and at least every two to three weeks after planting. After planting, apply shredded bark mulch up to 3 inches thick away from the base of the plant. Apply fertilizer a month after planting.
Small but mighty microgreens are easy to grow indoors
By Austin Little, Illinois Extension Horticulture Educator
With the winter upon us, gardeners may be looking for a new project to keep their green thumbs active.
Growing microgreens indoors is a fun and relatively easy project to set up. It also rewards the grower with fresh tasty produce in a short time period.
Microgreens are the tender new shoots of vegetables plants which are harvested before they reach maturity.
The basic supplies to get started with microgreens are a shallow container with drainage such as a plastic tray or pie tin. Takeout containers can even work, just remember to poke some holes in the bottom for drainage. The rest of the supplies include vegetable seeds, growing medium, a light source and maybe a bit of plant food.
That’s really all you need to get a tray or two of microgreens started this winter. Although many enthusiastic hobbyists upgrade with some starting successful microgreen businesses in their homes.
Many vegetables can be grown for microgreens including mustard, kale, endive, arugula, beets, radish, watercress, peas, cabbage, basil and most kinds of lettuce. Plants in the Solanaceous or nightshade family which includes tomatoes, eggplant and peppers, should not be grown as microgreens due to toxins in the stems and foliage.
Once seeds have been selected, the next step is to add the growing medium. The easiest way to get started is with a store bought premade potting mix or soil mixed with compost added to the container about 2 inches deep.
Since the shoots are harvested while they are immature, seeds need to be planted densely, about ¼ of an inch apart or less. After broadcasting a layer of seed, spread an additional thin layer of medium over the top to cover the seed and press down lightly to secure the seeds.
Water the soil so it is moist but not sopping wet. Some growers pre-moisten the medium before planting and then water a bit more after. Microgreens generally don’t require much added fertility, but it may help to include a small amount of water-soluble fertilizer or root stimulator nutrient solution with the first watering. Rates for these fertilizers are low, around a teaspoon per gallon of water.
Check the container daily to make sure the medium stays moist. Spray the medium once or twice a day or bottom water the container. By placing the growing container in a tray with a shallow layer of water, it can slowly take up water over several days.
Microgreens need about six to eight hours of light per day for optimal growth. A sunny south facing window is preferred. Alternatively, LED grow lights can provide the needed light. Also keep temperature in mind. Microgreens grow best around 70°F but will tolerate down to 50°F although growing slower. A seed starting heat mat can be used if temperatures are low.
Microgreens are ready to harvest in about 10 to 12 weeks. Take up the whole plant with the roots or cut them at the base with sharp scissors. In both cases, they need to be submerged in cold water and rinsed thoroughly. The greens can be harvested all at once and stored in the fridge or harvested as needed.
Compared to their full-grown versions, microgreens offer unique flavors. After a quick wash, you can ask them to salad or a stir-fry and on top of soups and sandwiches for a fresh crunch.
For further instructions, Illinois Extension has a recorded webinar on growing microgreens available go.illinois.edu/MicroWebinar.
Keep houseplants happy with simple solutions
By Sarah Vogel, Illinois Extension horticulture educator
Keeping houseplants is a source of satisfaction for many. But when plants are not thriving it can be concerning and confusing.
As soon as a leaf yellows or develops a brown spot, many reach for fertilizer or household pesticides, neither of which is an appropriate first response.
Yellowing, brown edges, leaf spots or drops are all symptoms something is ailing a plant and cultural or environmental conditions are often the culprit. Knowing what to look for can alleviate houseplant woes.
All species of plants have specific light, water, and soil condition needs. This houseplant care guide from University of Missouri Extension and available at go.illinois.edu/CaringForHouseplants outlines the basics of each.
Many plants go through an adjustment period whenever they are moved. This can happen whether it’s from the nursery to a home, the living room to a porch, or one window to another.
This may cause yellowing or leaf drop but the plant will eventually acclimate if in favorable conditions. If the yellowing continues longer than a few weeks, place the plant in another spot and change its watering schedule slightly.
Yellow leaves can also mean the plant is overwatered. A great way to decipher watering issues is to carefully remove the plant from its container and look at the roots.
With some exceptions, healthy plants generally have white roots. If the roots are rusty orange to light brown it is underwatered, and if the roots are dark brown to black it is overwatered.
Gently place the plant back in the container and adjust the watering schedule accordingly. If overwatering is the issue, withhold water until the soil is quite dry and gradually begin a new watering schedule. After two weeks, apply a water-soluble, houseplant-specific fertilizer. If no improvement is seen in the next two weeks, repot in fresh soil.
Yellowing may also occur if a plant needs to be fertilized. Depending on what nutrient is needed, yellowing may begin on the outer edges of leaves, or from the vein outward, or the leaf may even curl. Become familiar with the fertilization needs of each species. Occasionally a plant needs fertilization when it becomes root-bound and may simply need to be repotted into a larger container.
Leaf spots on foliage can be caused by too much sun. When spots appear consistently, move the plant to a place it receives less sun.
Leggy or stretching plants occur when they are reaching for more light. Move them to a brighter location or turn them occasionally to keep them growing evenly.
Some fungal diseases may also cause leaf spots so ensure proper circulation, remove and destroy infected plant parts, and allow soil to dry between waterings.
Brown edged leaves may indicate an erratic watering schedule or exposure to cold drafts. Another cause of brown leaf edges is an accumulation of fertilizer salts on containers. If other issues have been eliminated and the brown edges continue, scrub the edges of the pot and flush the soil with clear water.
Most common insect pests on houseplants include scale, fungus gnats, aphids, spider mites and mealybugs. If the plant is heavily infested with scale, it is best to discard it. Fungus gnats can be greatly reduced by letting the plant dry completely between waterings. Aphids can be controlled by washing away with water or using insecticidal soap. Spider mites often affect already stressed plants so keeping plants healthy is the most effective control measure. Horticultural oil or insecticidal soap may be used for spider mite infestations. Mealybugs can be wiped away with a cotton swab soaked in rubbing alcohol.
When using pesticides, make sure they are labeled for indoor use and read and follow all label directions.
If the problems persist, horticulture educators and master gardener volunteers are available to provide assistance at Illinois Extension offices around the state. Local offices can be located at go.illinois.edu/ExtensionOffice.
Keep poinsettias plentiful long after the holidays
By Ken Johnson, Illinois Extension Horticulture Educator
When it comes to the most popular holiday plant the winner is surprising. With their varying shades of cheery colors, poinsettias are the bestselling potted plant in the United States and Canada.
There are more than 100 varieties of poinsettias from the traditional red plants to pink, white, yellow and purple. If taken care of properly, their bright displays can last for several weeks says Ken Johnson, University of Illinois Extension horticulture educator.
“The colored parts of the plants aren’t flowers,” Johnson says. “They are actually modified leaves called bracts.”
The greenish-yellow flowers, cyathia, are in the center of the bracts. Poinsettias will drop their bracts and leaves once their flowers have shed all their pollen. So, for long lasting poinsettias, choose plants that have little or no pollen showing in their flowers.
One of the most longstanding myths about poinsettias is its toxicity.
“Contrary to popular belief, poinsettias are not poisonous,” Johnson says. “The misconception began in 1919 when an Army officer’s child allegedly died after eating a poinsettia leaf.”
While this was never proved and was later determined to be hearsay, the story has persisted. In fact, a study by Ohio State University showed that a 50-pound child would have to eat more than 1¼ pounds of the plant, 500 to 600 leaves, to have any harmful effects.
That being said, poinsettias may ooze a milky sap and some people that have latex allergies may have a reaction to it. This may also cause mild irritation and nausea in pets, so it may be best to keep them away.
Poinsettias are sensitive to extreme temperatures and cold temperatures can damage the bracts and leaves. Keep them wrapped when transporting them outside.
Once home, place poinsettias in indirect sunlight for six hours and make sure they aren’t touching windows. Poinsettias should have daytime temperatures around 60°F to 70°F and nighttime temperatures around 55°F. Warmer temperatures will shorten the length of the poinsettias display.
Poinsettias come wrapped in foil and plastic. If left on, make sure to poke holes in the bottom so water can drain out. Water poinsettias when the soil becomes dry and discard the excess. Waterlogged plants can get root rot and die.
After the holidays, fertilize poinsettias them once a month after they are done blooming.
For more information on poinsettias, visit go.illinois.edu/Poinsettia.
Prolong the shelf life of garden-fresh produce with good harvest habits
By Bruce J. Black, Horticulture Educator, Illinois Extension
The fruits of our summer labors have been ripening, and soon, more fruits and vegetables will be ready for harvest. As gardeners, overplanting is a common problem, and it is a struggle to get the longest life out of the harvest.
“Most of us end up with more produce than we can use,” says Bruce Black, University of Illinois Extension horticulture educator. “Neighbors, friends, coworkers, and others usually benefit from the overflow.”
The quality of harvested produce follows an 80-20 rule.
Most of what happens after it is harvested, 80%, is decided by pre-harvest factors such as genetics, environmental, and cultural factors. The remaining 20% is determined by how the produce is handled after harvest.
Home gardeners often pick specific fruit and vegetable varieties for their flavor, fresh consumption, or preservation needs. They don’t pick varieties for their built-in resistance to diseases or response to natural environmental conditions.
“Unfortunately, we have yet to figure out how to control the weather or the amount of sunlight yards receive,” Black says.
How gardeners respond to fluctuating natural conditions, such as high winds or drought, can give plants a fighting chance. These cultural responses are the things we can control: irrigation, fertilizing, pulling weeds or using pesticides, and choosing when and how to plant and harvest.
While the 80% pre-harvest factors may have more influence, the post-harvest 20% can actually make a significant difference with produce.
Tips to improve post-harvest quality and extend shelf life:
- Take care to prevent dropping, bruising, or picking injuries.
- Harvest produce during the cool part of the morning to limit heat damage. Shade fruit left outside if picking large quantities at once.
- Store similar produce together for optimum temperature and humidity requirements in refrigerator crisper drawers.
- Store ethylene producing produce (apples, melons and tomatoes) and ethylene sensitive produce (peppers, green beans, cucumbers and lettuce) separately.
Ethylene is the natural gaseous plant hormone mostly responsible for ripening. When a fruit or vegetable is injured, four things happen: increased ethylene production, increased rate of respiration, increased water loss, and the creation of an entry point for pathogens.
Taking these factors into consideration as you harvest should help your produce have a longer post-harvest life and give you time to plan how to best enjoy your harvest. Given the investment of the time, money, sweat, and even tears you put into your garden, getting extra time to savor their flavors just makes gardening sweeter.
For more information on postharvest, check out University of Illinois Extension’s Watch Your Garden Grow website.
Benefit your health and environment by growing your own vegetables
By Nicole Flowers-Kimmerle, Horticulture Educator, Illinois Extension
As summer comes to an end, many vegetable gardeners are busy reaping what they’ve sown and harvesting the fruits of their labors. Growing your own vegetables has health, nutritional, and environmental benefits, says University of Illinois Extension Educator Nicole Flowers-Kimmerle.
The health benefits are exponential with the combination of nutrients, sunshine, and exercise gained through gardening. Walking, bending, lifting, and pulling movements that naturally happen in the garden fit into the moderate excise category that can increase your body's immune system function.
Certain vegetables, such as broccoli, cabbage, and brussels sprouts, produce a disease-fighting compound called sulfurane after being cut. Colorful vegetables provide antioxidants such as lycopene and beta carotene. Eating a diverse group of vegetables ensures balanced nutrition.
“Different varieties of vegetables have different flavors,” Flowers-Kimmerle says. “Growing your own vegetables from seed allows you to choose varieties for your garden to suit your tastes.”
The flavor is also based on biochemical changes that happen to the produce once it is harvested. "The sugar in sweet corn kernels starts converting to starch as soon as the ear is harvested," Flowers-Kimmerle says. “Cook sweet corn as soon as you can for the sweetest flavor.”
Harvest timing can also affect the flavor of a vegetable. Harvesting vegetables at their peak ensures maximum flavor. Locally grown vegetables benefit the environment by reducing carbon emissions from burning fossil fuels to transport grocery store produce.
“No plastic packaging is required when you harvest vegetables straight from the garden, which also reduces fossil fuel inputs,” Flowers-Kimmerle says. Pesticide and other chemical inputs tend to be lower in small, well-tended gardens than even small farms.
When vegetable gardeners use kitchen and yard waste as compost, they keep it out of landfills and create their own soil amendment to increase the garden's productivity.
These health and environmental benefits can last even longer with cool weather plantings for a late fall harvest. Vegetables that grow well in cool weather, such as leaf lettuce, radish, spinach, and turnips, can be planted throughout August. Visit the Illinois Extension website Vegetable Garden Guide at web.extension.illinois.edu/vegguide for planting dates. For more information on how to start a fall vegetable garden, contact your county Illinois Extension office or visit extension.illinois.edu.
Harvest abundant squash for food, decoration
By Jennifer Fishburn, Horticulture Educator, Illinois Extension
Winter squash is a tasty, nutritious fall treat that comes in a variety of sizes, shapes, colors, and flavors. There are hundreds of varieties available to grow and enjoy on the dinner table.
“A few of the more popular winter squash include butternut, acorn, spaghetti, and butternut,” says Jennifer Fishburn, University of Illinois Extension horticulture educator serving Logan, Menard and Sangamon counties.
- Butternut squash is one of the most popular. This long, pear-shaped squash is tan, with a thin rind that is easy to cut or remove with a vegetable peeler.
- Acorn squash is a small squash that resembles an acorn and is available in a variety of skin colors, including dark green, gold, and white.
- Spaghetti squash, as its name suggests, resembles pasta strands when cooked. The strands can serve as a low-calorie, low-carbohydrate pasta substitute.
Harvesting and storing winter squash
Squash, a fruit, is generally harvested in September or October and must be harvested before a hard frost. A light frost will kill the vines, but won’t harm the fruit.
“Unlike summer squash, such as zucchini, which is harvested in the immature stage, winter squash is harvested when the fruit is mature,” Fishburn says. Their rinds are dull, dry, and hard and cannot be punctured with a fingernail. Rinds should be free of cracks and soft spots. Use caution not to injure the rind during harvest.
When cutting squash from the vine, leave a 2- to 3-inch stem. Avoid handling fruit by the stem since the weight of the fruit can cause the stem to break. Most winter squash, with exception of acorn and delicate, benefit from a curing process. To cure, place squash at a temperature of 70°F to 80°F for 10 days.
Winter squash have a long shelf life if stored properly. Acorn squash can be stored up to two months, butternut up to three months, and hubbard up to six months. Optimum storage conditions for most winter squash harvests is around 55°F with a 50% to 75% humidity in a cool, dark location with good air circulation. If possible, store squash in a single layer and keep fruit from touching each other. All winter squash except hubbards should be stored with stems attached.
Eating winter squash
Most winter squash can be baked, boiled, or steamed. Fishburn cautions that the hard, tough rind is a challenge for most cooks.
With the exception of spaghetti squash, winter squash is often eaten as a sweet or savory side dish. Squash can be flavored simply with salt and butter or with warm fall spices, such as cinnamon, ground cloves, nutmeg, or basil and sweetened with brown sugar, maple syrup, or honey.
Squash’s dense texture holds up well in soups, stews, chili, and casseroles. The flesh can also be used in pies, muffins, and cakes.
Hold on to summer with home hydroponics
By Chris Enroth, Horticulture Educator, Illinois Extension
Just because summer is over, doesn’t mean you have to stop gardening. Hydroponic systems allow year-round growing
The year 2020 has created a lot of new gardeners, says Chris Enroth, University of Illinois Extension horticulture educator. Some may have dabbled in hydroponics, the process of growing plants in a liquid nutrient solution without the use of soil.
“When it comes to gardening in the ground, it is important to manage the soil,” Enroth says. “Hydroponics shifts that focus to managing the nutrient solution. It’s not any less or more work, you’re just modifying your practices.”
What options do home gardeners have when it comes to growing plants hydroponically?
There are several at-home hydroponic systems sold by various companies. Some come with all the materials you need. Nutrients are pre-measured and applied based on the manufacturer’s instructions. Some even come with an app that walks users through the process of growing hydroponically.
While commercial at-home systems are convenient, they can be pricey
Many home hydroponic growers begin their journey with a passive system using simple plastic storage tubs with a locking lid. Choose a container that is not clear or opaque to avoid light getting to the liquid solution which will encourage algae growth.
“Cut round holes in the lid sized to suspend a netted plastic pot in the tub’s nutrient solution, but narrow enough so the lip of the pot cannot slip through,” Enroth says. ”The plant and the roots still need some type of structural support in the plastic pot. This is done with soilless media such as rock wool, perlite, coconut coir, expanded clay, or coarse sand."
An air stone attached to a pump helps inject oxygen into the solution and keeps the water moving. These can usually be found wherever aquariums are sold.
The biggest investment for an DIY hydroponics system?
This will likely be the EC, electrical conductivity, meter and pH meter. Some are priced as low as $20, while others are more than $200.
“Keep in mind this nutrient solution is your ‘soil,’ ”Enroth says. “Instead of a tiller, you are buying tools to manage your solution.”
EC meters measure the amount of salts in the solution, which gives an idea of how much nutrition is available for the plants. The pH meter measures the water’s acidity or alkalinity, which will vary by source. Most plants do well in a slightly acidic range of a 5 to 6 pH level, Enroth says.
With the EC and pH measurement readings, users can adjust the nutrient solution as needed. “I’ve often found kits that include the meters and amendments take most of the guesswork out of managing the nutrient solution,” Enroth says.
One crucial component is supplemental light. An inexpensive shop light works well, and new LED technology is promising for indoor plant production.
Plant choice is important for indoor hydroponic systems:
- No: Tomatoes, zucchini
- Yes: lettuces and herbs
“We grew basil in our hydroponic system and it did exceptionally well,” Enroth says. “Even if you don’t eat it, we just loved brushing against the leaves as winter sets in to give us a feeling of summer.”
Harvest milkweed pods; plant Monarch butterfly garden
By Kelly Allsup, Horticulture Educator, Illinois Extension
Illinois needs to plant milkweed, and a lot of it, over the next 18 years to ensure the state’s official insect, monarch butterflies, survives.
Kelly Allsup, University of Illinois Extension horticulture educator, says the task of planting 150 million new milkweed stems by 2038, championed by the Illinois Monarch Project, needs public buy in.
“Major statewide strategies, such as updated roadside mowing guidelines, creating habitat in natural areas, and allowing it to grow in farmland not in production, may not be enough,” Allsup says. “Monarchs may need homeowners to plant a larger patches of milkweed.”
The prairie state, as its name suggests, was once covered in grasses and flowers that were habitat and food for migrating butterflies. Development has reduced the availability of milkweeds, which is the only food source for monarch caterpillars. Monarchs (Danaus plexippus) will be considered for inclusion on the Endangered Species list in December 2020.
Anyone can grow milkweed in their yard or garden, Allsup says. “Do you have an alley that does a good job at growing weeds? Perhaps you are ready to move on from a ditch full of daylilies, or you have an empty garden bed. One 10-square-foot garden can hold 150 stems of milkweed.”
Harvesting and germinating milkweed seeds
While there are a number of different species of milkweed, monarchs prefer swamp milkweed (Asclepias incarnata), Butterfly weed (Asclepias tuberosa), Common milkweed (Asclepias syriaca), Prairie milkweed (Asclepias sullivantii), and Whorled milkweed (Asclepias verticillata).
“With permission from landowners, you can pick milkweed seed pods this fall rather than buying seeds or purchasing plants,” Allsup says. “Once harvested, you can either plant them in the fall or wait until spring.”
Each pollinated milkweed flower forms one to two large teardrop-shaped green pods that turn brown or maroon as they mature.
“Pick pods when they are dry and just starting to split open,” Allsup says “Seeds can’t germinate if they have not been allowed enough time to mature on the plant.”
Allow pods to dry out then pry them open and separate the seeds by holding one end and stripping the seeds away from the white fluff known as floss.
“Another way to separate the mature seeds from the floss is to place the seeds in a paper bag with a coin,” Allsup says. “Cut a hole in the bottom of the bag so the seeds fall out after a good shaking.”
Once you’ve harvested the seeds you can plant them this fall or store seeds in a dry and cool place in a labeled paper envelope with species, date, and location to plant them in the spring.
Milkweed seeds need to be stratified and require cool moist conditions, to germinate. Growers can accomplish this at home by placing seeds in a damp paper towel in the refrigerator for four to six weeks. Start seed germination in early April to have them ready for planting after the last frost in May.
Steps to planting milkweed
- Clear out any weeds or existing plants and water the soil.
- Place germinated seeds about 12 inches apart and 1 to 2 inches deep. Tip: Plant two seeds per hole and if they both germinate, remove the weakest one.
- Cover with moist soil.
- Put flags or bamboo sticks near your planting holes and mulch with straw.
- When the seedlings come up, consider transplanting or culling plants to achieve 2 foot spacing.
- Weed aggressively every two weeks as the plants grow bigger. A fertilizer can be used when the seedlings start to grow to give them a jump start, but after that, fertilizer is generally not needed, Allsup says.
“Milkweed gardeners can record their efforts so the Illinois Monarch Project knows if they are reaching their goal,” Allsup says. Milkweed plantings can be submitted at monarchwatch.org/waystations/#register. Illinois gardeners can also register their habitat as a Pollinator Pocket or Monarch Waystation at extension.illinois.edu/cfiv/pollinator-pockets.
Bring houseplants indoors before the first frost
By Ken Johnson, Horticulture Educator, Illinois Extension
As fall draws near, it’s time to bring houseplants inside for winter. Many houseplants are native to tropical and subtropical climates and do great outside in Illinois in the summer, but cannot tolerate cold temperatures.
Insects, such as aphids, whiteflies, scale, and spider mites are pests commonly found on outdoor plants. Inspect plants for any insects and other pests before bringing them indoors. Once inside, populations can rapidly increase and spread to other plants.
Before resorting to insecticides, spray foliage with a steady stream of water. “If spraying doesn’t work, insecticidal soaps can be used to eliminate soft-bodied insects,” Johnson says. "Follow label instructions.”
If plants are infested, it may be prudent to dispose of them.
In addition to the foliage, Johnson recommends checking the soil. Insects, such as earwigs and ants, will move into soil in potted plants. Flush pots with water to drive out insects. If ants are present, the plant may need to be repotted.
Over a period of about a week, gradually reduce light levels by moving plants to increasingly shadier areas. This will start to acclimate them to light conditions indoors. Once plants are indoors, put them next to the brightest, sunniest window, typically south or west facing. If you don’t have a sunny location, provide supplemental lighting.
Plants grow slower indoors, so will need less water and fertilizer. For most plants, allow the soil to dry slightly between watering, Johnson says.
“One way to check soil moisture is with your finger,” he says. “Stick your finger in your potting media up to your second knuckle. If the media is still moist, you don’t need to water.”
If the pot feels light when lifted, it may be time to water.
Plants can be watered by top or bottom. If top watering, apply enough water so that some water comes out the drainage holes at the bottom of the pot. This may need to be done more than once if the soil is very dry. If you have a saucer under the pot, make sure to empty the water out after half an hour or so. This will allow the potting mix to absorb additional water, but prevent the mix from becoming saturated.
To water from the bottom, fill you’re a plant saucer or sink with a few inches of water and let plants soak. Once the potting mix on the top of the pot is moist, the plant can be removed from the water.
Plants often drop leaves and yellow when they are moved indoors. Increasing humidity levels around plants and providing supplemental lighting can help reduce leaf drop, Johnson says. Over time, plants will acclimate to their new environment.
Select and plant spring-flowering bulbs now
By Brittnay Haag, Horticulture Educator, Illinois Extension
As fall approaches, many perennial plants are ready to go dormant for the winter. Now is the time to start thinking about next spring’s floral display and planting spring-flowering bulbs.
Since spring bulbs need a cold period during the winter in order to bloom, the best time to plant is late September through October to allow sufficient time for a good root system to develop, says Brittnay Haag, University of Illinois Extension horticulture educator.
“Investing a little time and money in the fall will pay off greatly next spring when you start seeing pops of color blanketing your garden,” Haag says. “Depending on the location, spring bulbs, such as snowdrops, begin blooming in late February and continue until late June with alliums.”
Bulbs should be firm and free of rotting spots or signs of disease. “When buying bulbs, keep in mind that larger bulbs will produce larger blooms,” Haag says.
If the bulbs cannot be planted immediately after purchasing, store them in a cool, dry place away from ethylene-producing fruits, such as apples, bananas, melons, pears, and peaches to prevent flowering disorders.
For the greatest visual impact, plant bulbs in groupings and large drifts or waves of color. Mix them in with other perennials and shrubs to screen the foliage after blooms fade. To produce maximum blooms, most bulbs will need at least eight hours of sunlight daily.
Most bulbs require fertile, well-drained soil to prevent the bulb from rotting. Poorly drained soil can be improved by adding organic matter such as compost or peat moss. The material should be incorporated into the soil before planting at a rate of four-parts soil, one-part organic matter. A balanced fertilizer, 20-20-20, can also be incorporated into the soil at this time.
“The general rule of thumb when planting bulbs is to plant them two to three times the length of the bulb, measured from the bottom of the bulb,” Haag says.
Large bulbs, such as daffodils or tulips, should be planted 6 to 8 inches deep. Small bulbs, such as snowdrops and crocus, should be planted 3 to 4 inches deep. Bulbs should be spaced 6 to 12 inches apart to allow for the spread and future divisions. Plant bulbs with the nose of the bulb facing upward and the root plate facing down.
After covering the planted bulbs with soil, water the area well to settle the bulbs into the soil and initiate root development. If there is little rain in the fall, continue to water weekly until the ground freezes. A light, 2-inch layer of mulch can be added after planting to minimize effects of winter temperature fluctuations and to help converse soil moisture.
“Spring bulbs can vary in flower color, timing, height, and shape depending on the species and variety,”says Haag. “Add a new type of bulb each fall to have a beautiful mix of spring bloomers in your garden.”
Visit Illinois Extension's website for more information about spring bulb selection.
Plant native perennials in the fall for healthy spring growth
By Austin Little, Horticulture Educator, Illinois Extension
Retailer shortages of the most popular native perennial plants were common this spring as there was an unprecedented run on supplies. But fall is another great opportunity to plant, says Austin Little, University of Illinois Extension horticulture educator.
It’s often recommended to plant herbaceous natives like butterfly milkweed or echinacea from transplants in the spring; however, planting in fall has a few more benefits than spring, such as improved establishment and flowering in the following spring, better vigor, and greater weed suppression, Little says.
Native plants are a critical part of our ecosystems and contribute to beneficial insects, birds, wildlife, and important microorganisms living in and on soils.
In the fall, soils hold onto heat longer even as above-ground temperatures are dropping, which is ideal for new root structures to grow. The root systems need time to establish new micro or feeder roots which helps the transplant to acclimate, then gradually go into dormancy as colder winter temperatures arrive. Fall transplants have better root structure and more time to acclimate to the local environment.
Herbaceous native perennials transplants or seeds can be ordered online or from a local nursery. Plugs are easier to plant and establish quicker. They need to be planted about six weeks before the first frost of fall. In Southern Illinois, the first frost date is historically in the last two weeks of October. Northern Illinois is a week or two sooner than that, so be sure not to plant too close to the first frost.
“If direct seeding, wait until the first hard frost to apply the seed to a weed-free bed with open soil so the seedlings do not germinate prematurely,” Little says. “Most native herbaceous perennials have very small seeds and need only a thin layer of soil and mulch to undergo the chilling process known as stratification.”
Transplants need to be thoroughly watered when they are installed. To encourage deeper root growth, it’s better to water less often but more deeply, once or twice a week for about 30 minutes depending on rain and temperature. When it’s getting close to the average first frost date, Little says it’s a good idea to back off on the water.
“Even if it warms up a bit in late fall, it’s best to hold off on watering to avoid interrupting the hardening off process,” he says.
Fertilizing in the fall is not recommended. Many native herbaceous plants are adapted to lean and low fertility soils. Adding nitrogen and other nutrients in the fall may cause the transplant to put energy into new vegetative growth that will be damaged by winter conditions and suppress the establishment of roots. Hold off on fertilizing until early spring, Little recommends
Do add a 2- to 3-inch layer of mulch or compost around the base of plants, making sure to leave some open space around the stems to avoid harboring unwanted pests and moisture build up. Fall plants don’t need to be mulched immediately after planting and can benefit from the sun warming the soil. Mulching can wait until night-time temperatures are in the 32°F range. By adding mulch, such as straw or finely shredded hardwood wood, and making sure plants are well anchored in the soil, frost heaving can be avoided.
Adding fall compost around any new plants is also recommended. By spring, most of the compost will be broken down and ready to be taken up by plants with root structures that have a head start on spring transplants.
Tips for fall planting native perennials
- Order and buy plants with enough time to plant six weeks ahead of the first frost.
- Water deeply once or twice a week, then stop watering after the first hard freeze.
- Help overwinter fall transplants with mulch and compost.
- Do not fertilize new transplants until spring.
Planting trees boosts curb appeal and benefits the urban environment
New homeowners often wonder about the value of planting shade trees when they first move in when there are so many more areas to focus on with a new home.
“Planting shade trees is an investment for the future just like other home upgrades,” says Richard Hentschel, University of Illinois Extension horticulture educator. “A smaller, young tree will be cost effective and will increase in value along with your home as well as providing indirect benefits.”
Trees can be planted throughout the year, depending on how they were grown. Fall and spring are prime times homeowners can consider a planting project to provide the extra care and time needed during transplant recovery.
Environmentally, there are several positives that come from having shade trees in the home landscape. The recent devastation caused by the invasive Emerald Ash Borer has taught developers the need for shade tree diversity. A single tree species and its cultivars should make up no more than 20% of the urban forest in order to survive stressful environmental conditions such as repeated droughts and severe winter conditions.
“Younger trees tolerate these conditions better than older trees, so new trees need to be continually planted,” Hentschel says.
A big benefit for human health is a tree’s ability to generate oxygen while reducing carbon dioxide in the atmosphere by collecting and storing carbon as they grow and mature. You’ve heard about industry carbon credits? Well, trees have always done this.
Shade trees also absorb water and hold soil in place, two benefits during severe weather conditions such as floods.
Trees support insect populations that create the balance of nature and are part of the natural food chain. Illinois white oaks support more than 500 insect species throughout the growing season, mostly butterflies and moths. Their caterpillars are not only the main food source for migrating and breeding birds, but also are essential food for baby birds. That shade tree supports birds, squirrels, and more wildlife by providing food and shelter.
One big benefit of shade trees for homeowners can be the long-term energy savings. An air conditioner will not work as hard or stay on as long when your house is shaded by trees. Temperatures can easily be 5 degrees or more cooler in the shade.
“It’s estimated that one tree is the equivalent of 10 window air conditioner units,” Hentschels says. “Two trees shading the west side of a home from the harsh afternoon summer sun have the potential of reducing cooling costs by 30%.”
In the winter, a deciduous tree allows sunshine to warm the home and the windowsill providing a nice warm spot for a cat.
There is no doubt the value of a home is increased when surrounded by mature shade trees, but they also encourage neighborhood socialization.
“There is a growing body of research that indicates plants and trees are a major benefit to mental health,” Hentschel says. “They also provide a sense of unity.”
Aesthetically, they offer beauty with springtime blooms and greenery and come fall the bright reds, yellows and golds of changing leaves. If there is shade to gather in and talk, adults are more likely to stop and pass the time as children climb tree branches or play in a tire swing.
For more information about selecting a tree for the home landscape, visit web.extension.illinois.edu/TreeSelector.
Fall flowering witch hazel charms home gardens
By Gemini Bhalsod, Horticulture Educator, Illinois Extension
With a name befitting the season it blooms, common witch hazel is a fall favorite for Illinois gardeners looking to add a small tree with character to their yard.
“People are very interested in plants that add some interest to their landscape in fall and winter,” says Gemini Bhalsod, University of Illinois Extension horticulture educator. “Common witch hazel is one of my favorites because it supports pollinators and has unusual yellow flowers.”
There are many different witch hazels, all in the Hamamelidaceae plant family. Common witch hazel, or Hamamelis virginiana, is native, although it is uncommon in natural areas as Illinois is the western edge of its native range.
“Witch hazel is a beautiful addition to any garden because of its linear yellow flowers,” Bhalsod says. “The long, thin petals give the small flowers an interesting texture that stands out in the fall.”
Since common witch hazel blooms late in the year, its flowers blend in nicely with the colorful turning of the leaves. In Northern and Central Illinois, it flowers around mid-October, and in Southern Illinois, near the end of October.
Witch hazel is susceptible to few pests and diseases making it a great low-maintenance addition to any landscape. It even supports wasps, flies, and various moths.
“You might not think of flies or small wasps when you think of pollinators, but just like bees and butterflies, they are important to our ecosystem,” Bhalsod says. “Witch hazel also provides crucial cover for birds, who also eat its seeds.”
Take an inventory of the conditions in your yard before planting a witch hazel tree in early spring. Witch hazel is also sometimes called a large shrub because it might have one trunk or multiple trunks, but it can grow to be about 20 feet tall. It provides enough screening for edges and borders, but also works well as an understory tree.
It blooms the best when planted in part-sun, but it is adapted to many different growing conditions and is relatively shade tolerant. It works well in sandy to loamy soils with good drainage.
Find more information about witch hazel on the Garden Scoop blog.
Exfoliating bark trees add great appeal
By Andrew Holsinger, Horticulture Educator, Illinois Extension
There are plenty of ornamental features to get excited about when it comes to trees, but one interesting feature often gets overlooked: exfoliating bark.
The process of shedding bark, or exfoliating, is normal for some trees. Weather influences this process, including how much of bark is shed in a season.
A word of caution though: peeling or exfoliating bark is not a good sign for trees that don’t naturally exhibit this bark characteristic and can be a sign of problems.
“Bark can be a helpful identification characteristic when identifying trees,” Holsinger says. “Some Illinois native trees with exfoliating bark include sycamore, river birch, bald cypress, ironwood, and eastern red cedar.”
The bark of most young trees is smooth and thin. As the tree matures, the bark becomes thicker, protecting the tree. The outermost layer of bark dies and naturally sloughs off, but with exfoliating trees, this layer peels and reveals the inner layers of bark.
Even in the actively growing state, Holsinger says, the exfoliating bark is a nice feature that can add to the uniqueness of the home or urban landscape.
Exfoliating bark trees provide a great home for bats. Many of bat species native to Illinois use trees with exfoliating bark for summer roosting and maternity colonies.
Some exfoliating bark species are fire resistant. The bark acts somewhat like an insulator protecting the tree.
The following trees have exfoliating bark characteristics and can create a focal point for your landscape:
- Bald Cypress (Taxodium distichum)
- Birch (Betula spp.)
- Black cherry (Prunus serotina)
- Dawn redwood (Metasequoia glyplostroboides)
- Eastern red cedar (Juniperus virginiana)
- Ironwood/hophornbeam (Ostrya virginiana)
- Lacebark elm (Ulmus parvifolia)
- Paperbark maple (Acer griseum)
- Redbud (Cercis canadensis)
- Scotch pine (Pinus sylvestris)
- Shagbark hickory (Carya ovata)
- Sycamore (Platanus occidentalis)
- Zelkova (Zelkova serrata)
Fall is a great time for planting trees
By Ryan Pankau, Horticulture Educator, Illinois Extension
Most people think of spring as the ideal planting time for trees and shrubs, but fall offers a nice planting window with some added benefits.
“Fall is my favorite time of year to establish woody plants,” says Ryan Pankau, University of Illinois Extension horticulture educator. “With temperatures cooling off, roots need less moisture. And, Illinois typically gets enough fall rains to help ensure adequate soil moisture going into winter.”
All trees and shrubs experience transplant shock, which can last two to three years, sometimes even longer. To overcome transplant shock, trees and shrubs need to expand their root system beyond the planting hole. A mature tree will typically have a root system two to three times wider than the spread of its limbs. When you think about that ratio for a newly planted tree, it takes considerable time to develop an adequate root system.
The most common mistake when planting a tree is digging a hole that is too deep.
“We can really help a tree overcome transplant stress by digging a shallow, wide planting hole,” Pankau says. “A wide hole with well-loosened soil where the edges are roughed up provides a nice space for roots to grow into the native soil.”
Planting holes don’t need to be deep because most of the tree roots are concentrated in the upper 12 to 18 inches of soil. Trees need to be planted at the proper depth, which is typically shallower than expected.
To determine the proper planting depth, start by identifying the root flare, or trunk flare, on a new tree. The flare is the portion of the trunk at the bottom of a tree that begins to flare out, or taper out, as trunk tissue transitions into root tissue. The flare needs to be even with the soil surface.
Trees that are planted too deep struggle to establish and often suffer from a lifetime of other issues. Improper depth is the most common mistake in tree planting because the depth of the tree’s original container, or root ball on balled and burlapped trees, is misleading.
“The root flare of the tree is commonly buried in the pot or down in the root ball on most nursery stock,” Pankau says.
If the root flare on your new tree is not easily identifiable, gently dig down into the container or root ball to search for the first root or roots coming out of the trunk. A young tree will have little trunk taper, making the first roots the best indicator of the root flare.
Mulch provides the finishing touch by adding a protective layer to the soil that retains moisture and prevents roots from freezing. Apply a 2- to 4-inch layer of mulch as wide as your planting hole was dug.
Next spring, the tree will awaken from dormancy and its winter rest with a full canopy of green leaves.
Select the right tree for fall planting in Illinois
By Nancy Kreith, Horticulture Educator, Illinois Extension
After spring, fall is the next best time to plant a tree. When adding trees to the landscape, it’s important to research and make a suitable list of tree species. Select a proper planting location based on mature size, preferred soil conditions, disease and pest resistance, and multi-seasonal interest, says Nancy Kreith, University of Illinois Extension horticulture educator.
“While shopping for trees at a garden center, inspect them carefully before purchasing,” Kreith says. “Look to make sure no roots are exposed. Inspect the trunk for damage, such as cankers. Be sure the container or root ball is the appropriate size compared to size of tree canopy and that trees have been watered on a regular basis.”
There are many tree species that do well throughout Illinois’ zones. These trees are appropriate for fall planting and includes native and non-native species:
- Kentucky coffee tree (Gymnocladus dioica): This Illinois native grows 60 to 75 feet tall and prefers full sun and moist, well-drained soils. It has fragrant, white flowers in the spring and persistent fruit pods. Pods can be messy, so consider a male cultivar. There are no serious pest problems and the Kentucky Coffee tree is adaptable to urban conditions, tolerating drought and pollution.
- American elm ‘New Harmony’ (Ulmus americana ‘New Harmony’): Although an Illinois native, this cultivar or another resistant cultivar, should be planted due to risk of Dutch elm disease. This tree grows up to 40 feet tall and prefers full sun and moist, well-drained soil; however, it will tolerate a range in soil pH and is wind and heat tolerant. It features a picturesque vase shape and has a nice yellow fall color. Morton Arboretum offers a list of pest resistant American elms.
- Downy serviceberry (Amelanchier arborea): This 10- to 30-foot tall Illinois native requires little maintenance and is best transplanted balled and burlapped. It features smooth gray bark, excellent fall color, and slightly fragrant white flowers in mid-spring. Best placement is in full- to part-sun and moist- to dry-conditions with well-drained soil.
- Redbud (Cercis Canadensis): This Illinois native grows 15 to 30 feet in height and prefers part sun and rich, moist, well-drained soils. Pink blossoms occur in mid-spring before leaves appear. Seedpods can persist through winter. This tree is naturally short-lived. If dieback occurs, cutting it to the ground encourages sucker growth than can become a substantially-sized tree.
- White fir (Abies concolor): White fir grows 30 to 50 feet high. This pyramidal evergreen tree that prefers full- to part-sun and moist, well-drained, sandy soils. It is valued for its silvery green foliage and useful for screening or as a specimen tree. It is relatively pest free and performs well in Midwest conditions.
- Limber pine (Pinus flexilis): This 30- to 50-foot-tall evergreen tree prefers full- to part-sun and moist, well-drained soils. This long-lived species works well as a specimen tree. It is adaptable to dry soils, windy sites and is more tolerant to salt spray than most pines.
- Serbian spruce (Picea omorika): This evergreen grows 50 to 60 feet high and prefers deep, rich, moist, well drained soils. It tolerates part-shade and urban conditions, except for pollution. It serves as an excellent specimen tree, with dark green needles and contrasting white on the underside.
Consider cultivars bred for certain characteristics. Redbud ‘Lavender Twist’ is a weeping form that reaches 4 to 5 feet high. Serbian spruce 'Sky Trails' has a weeping habit, with blue-green needles and contrasting white underneath. Kentucky coffee tree 'Espresso' features a vase-shape, and its male cultivar will not produce fruit.
Wait until spring to plant trees, such as hemlock, willow, river birch, white oak, bald cypress, ginkgo, sweetgum, magnolia, American hophornbeam, or hornbeam since establishment is often difficult and slow, Kreith says.
Put fall leaves to work as compost
By Sarah Vogel, Horticulture and Natural Resources Educator, Illinois Extension
“The science behind composting may sound technical, but it is as simple as throwing leaves and food scraps in a pile and using a shovel to move it around,” says Sarah Vogel, University of Illinois Extension horticulture educator. “Composting can be a great way to reduce the amount of biodegradable material entering landfills and save money by reducing lawn bag use.”
Compost is organic material, meaning it comes from an organism that was once alive. Composting is the breakdown of organic material through controlled decomposition. This decomposition can occur aerobically with oxygen, anaerobically without oxygen, or sometimes, even with worms.
Aerobic composting, or allowing oxygen into the mix, can be accomplished on the ground or in a tumbler. A tumbler is a receptacle that keeps things tidy and is easy to turn but dries out faster and does not receive beneficial microbes from the soil unless added. For those who have a small garden or do not produce a lot of organic waste, a tumbler may be a good option.
“Many people compost in a pile or a bin system,” Vogel says. “There are several do-it-yourself bin systems also available for purchase. A pile is a very simple way to start and easy to access when turning the compost.”
Depending on the size of the compost pile, what is added, and how often it is tended, compost can take anywhere from 90 days to two years to become usable. Using the three-bin or three-pile method, each of the three piles are in varying stages of development: new, partly aged and usable. Composters can speed up the process by turning more frequently.
To start a compost pile, select a shady spot as moisture content will remain important for decomposition. To create good compost, use one-part green materials (the nitrogen component) and two parts brown materials (the carbon component). Add greens and browns in alternating layers, occasionally adding non-glossy newspaper or a bit of soil. Turn every 30 days to aerate and mix.
- Greens: Kitchen scraps and coffee grounds, fresh grass clippings, livestock manure.
- Browns: Fallen Leaves, non-glossy shredded paper or cardboard, wood ash, straw, sawdust, hair trimmings.
- Do not compost: Diseased or pesticide treated plants, weeds with seed heads, twigs, meat or bones, dairy products, human or pet waste.
Compost will produce heat as a by-product of the microbial breakdown of organic material. The amount of heat will depend on the size of the pile, moisture content, aeration, and the carbon-to-nitrogen ratio. When the compost is ready, it will be dark in color and smell earthy and rich.
How a compost smells will tell you a lot about how to troubleshoot any issues.
- For an ‘off’ odor, add browns.
- Damp and smells sweet, but not heating up, add greens.
- Ammonia smell, add browns.
- Compost is dry, add material in layers and cover to lock in moisture.
Fall garden cleanup lays groundwork for a successful spring
By Martha Smith, Horticulture Educator, Illinois Extension
Don't put that trowel and rake away yet. Fall may end this year's gardening season, but it is the perfect time to begin preparations for next year. Taking care of a few details now means fewer chores, pests and problems next spring.
The first step is taking stock of how your garden fared this year. Do a walk-through and take notes on plant location and performance, says Martha Smith, University of Illinois Extension horticulture educator.
“You should sketch out your vegetable garden,” Smith says. “Crop rotation is very important when it comes to vegetable diseases. In the spring, you can refer to your sketch rather than rely on your memory and plant vegetables in different locations.”
Perennials and annuals should also receive a year-end review. Note whether this season's plants met expectations or if different plants and varieties are needed for next year. Perhaps choosing a different location for certain varieties will help their performance. Do any perennials need to be divided? Do it now or make a list for next spring.
Landscape clean up
Diseased plants should be completely removed. Healthy plant debris can be added to your compost pile. If any perennials have been seriously and routinely plagued with disease, fall is the time to discard them before they spread problems to other plants.
After the first frost, remove annuals and cut back tops of tall herbaceous perennials. Many gardeners prefer to leave most of their perennials as they are, cutting them back in the spring. Tall perennials more than 3 feet tall will flop over under the weight of snow or ice and create environments for rodents and other wildlife; many may reseed..
“I always cut seed heads off of Northern Sea Oats (Chasmanthium latifolium) and Blackberry Lily (Belamcanda chinensis) before they spread,” Smith says. “But if you want more, let them be.”
Dig up tender bulbs such as gladioli, dahlia, and canna lilies. Dry them, and store over winter in a cool, frost-free area. Garden centers have hardy bulbs such as tulips, daffodils, and crocus in stock now. Check out the selection and plant in October and November for spring blooms.
Leaves in the landscape
Rake leaves and add them to your compost pile or locate them near the garden so they are handy to add as mulch next spring and summer.
Don't let fallen leaves accumulate and mat down over your desirable turf. After the heat of summer, grass is actively growing in the fall. Leaves smother the grass and prevent photosynthesis which is the plants ability to produce food. Consider using fallen leaves as winter mulch around tender plants.
Container plants should be pulled and added to your compost pile. Saving potting mix to replant for next year is difficult. Roots are not going to disappear over winter and you will have to deal with them sooner or later. Potting mixes will also lose their organic matter content since it breaks down through the growing season.
Throw roots and media in the compost pile if this is the case and clean out the container with a mild bleach solution of 10-parts water, one-part bleach.
If saving the soil for next year, store it in a dry area or cover it with plastic to keep out debris and prevent it from getting waterlogged.
“Now, you can begin to put away your garden tools,” Smith says. “But while you're at it, remember to clean the tools, wipe the metal blades with oil, and store them under cover so they too are ready for next year.”
How to pick the perfect pumpkin
By Ron Wolford, Horticulture Educator, Illinois Extension
When you think of Halloween, you may think trick-or-treating and fall, but you likely also think pumpkins.
“In 2018, Illinois pumpkin farmers produced an estimated 500 million pounds of pumpkins,” he says. “The town of Morton claims to be the Pumpkin Capital of the World, with 82% of the world's canned pumpkin processed there.”
Although jack-o’-lantern pumpkins are edible, other squash varieties have better texture for making pies, soups, and breads. The world's largest pumpkin pie was made at the New Bremen, Ohio, Pumpkin Fest in 2010. The pie was 20 feet in diameter and weighed 3,699 pounds.
Pumpkins are grown on every continent except Antarctica. The largest pumpkin on record was grown in 2016 and weighed 2,624 pounds.
Tips for selecting the perfect pumpkin for carving
- Choose a pumpkin with a stem at least 1 to 2 inches long. Never carry it by the stem.
- Select a pumpkin with a flat bottom, so it will stand upright.
- Avoid pumpkins with holes, cuts or soft spots. These areas will decay.
- Use the thumbnail test. Press your thumbnail into the pumpkin, if your nail makes a scratch in the pumpkin, do not select.
- Color is also important. Light-colored pumpkins are easier to carve because the skin is not as hard as darker ones, but they will not keep as well.
Before carving or display, wash the pumpkin with warm water and let it dry. The pumpkin will last longer in a cool place. After carving, coat the inside of the pumpkin and the cuts with petroleum jelly. A pumpkin cut for Halloween will last seven to 10 days depending on weather conditions.
Avoid using candles to light a pumpkin because the heat will cook the flesh, shortening its lifespan.
For more information about pumpkins, check out the Illinois Extension website Pumpkins and More.
Growing a rainbow vegetable garden
By Bruce J. Black, Extension Educator, Horticulture
Color is one of the aspects of design that leads to the beautiful garden, but sometimes vegetable gardens lack a variety of hues.
Thumbing through garden catalogs, you can now find a variety of colorful cultivars. These colors come from pigmented phytonutrients: phyto means plant. For example, the phytonutrient lycopene is red and can be found in tomatoes, carrots, peppers, and red cabbage.
White vegetables do not develop chlorophyll, or pigmented phytonutrients. This is often due to blanching or etiolation, which is excluding sunlight to prevent the plant from producing chlorophyll.
Color can be a great way to get picky eaters – children and adults – to try vegetables. It can also get people involved in the garden by growing their favorite color. Plus, growing purple carrots and yellow cucumbers is fun.
If you’re looking to add some uniquely colorful to your garden, these vegetables are great places to start.
Carrots come in shades of orange, red, yellow, purple, and white. Although not a true black, ‘Black Nebula’ is a purple carrot variety that is so high in anthocyanins that it looks black with a lighter purple center.
If you want to take your carrot colors further and have fun, you could plant a themed colorful carrot garden with these cultivars ‘Black Nebula,’ ‘Lunar White,’ ‘Atomic Red,’ and ‘Solar Yellow.’
Peppers are known not only for their heat, but also their beautiful colors. Peppers can have shades of green, red, orange, yellow, purple, and white. Most people are familiar with the triad pack of yellow, red, and orange bell peppers at the grocery store, but depending on your heat tolerance, that is just the start of the colors. 'Sweet Chocolate' peppers might not taste like chocolate, but they have the glossy brown color of melted chocolate. 'Mixed Cayenne' is reminiscent of Mardi Gras colors: purple, red, yellow, and green. These peppers are great for cooking, eating fresh, and they can even be made into a dried colorful cayenne pepper powder.
In recent years ‘Lemon Cucumbers’ have been more readily available at garden centers. ‘Lemon cucumbers’ are yellow and have a similar appearance of lemons inside and out. Another unique cucumber is ‘Poona Kheera.’ This cucumber is reminiscent of a russet potato at maturity. During growth, it has a white skin that turns into the golden-yellow russet color. The ‘Poona Kheera’ is also a hardy, disease-resistant, 55-day cucumber.
Whether you are a new gardener or have been gardening for life, splash some new color into your vegetable garden and liven up your next meal.
5 ideas to add shade to your backyard
By Nancy Kreith, Extension Educator, Horticulture
Relaxing outdoors while surrounded by plants is a great stress reducer in the summer. As temperatures heat up, you can prolong your time outside by creating some shade in your yard.
Shaded areas let you stay outside longer without getting exhausted from the sun. Try incorporating some of these landscape design elements to make the most of your yard this summer.
- Plant a shade tree: Putting a tree on the south or west side of your yard can block the intense afternoon summer sun. Of course, it will take time for the tree to mature and provide ample shade, but this is an inexpensive, long-term option. When planting trees, be sure to follow appropriate planting and post-care techniques. Water your tree well the first three years after it's planted.
- Put up a canopy tent: Turn patios and seating areas into shady sanctuaries with a canopy tent. Canopy tents come in a variety of sizes and styles and can be easily stored over the winter. During inclement weather, keep an eye on the tent so wind or heavy rainfall does not damage it. Anchor the legs so it does not blow away and remove pooling water from the canopy as soon as possible so it does not collapse. For a more attractive feature, explore shade sails, large patio umbrellas, or retractable awnings. There are many options available.
- Build a gazebo or pergola: These permanent structures are an option if your budget allows it. Design your own or have a carpenter or company install a prefabricated kit.
- Hang patio curtains or shades: If you have an existing structure or decide to build one, patio curtains add a soft touch and can be adjusted to provide shade from different directions as needed. To lower the cost, consider using fabric you have on hand, roll-up shades, or shower curtains. UV-protected materials will last the longest outdoors.
- Install a water feature: This could be as simple as a fountain or something larger like a pond or reflecting pool. Situate the feature to take advantage of summer breezes blowing across the water and cooling the air. The most important rule is to keep water circulating, which can be done with a bubbler or low-flow pump.
As you consider these features, be sure to follow installation instructions and look up building codes in your area for rules on permanent structures and water features.
‘Annabelle’ hydrangea: A showy shrub with historic roots in Illinois
By Ryan Pankau, Extension Educator, Horticulture
The ‘Annabelle’ hydrangea has been a mainstay of the ornamental shrub world since its release in the 1960s. This showy shrub is filled with beautiful snowball-like flowers that adorn its spindly branches each summer. The blooms begin as pretty green puffs that turn white at maturity, often lasting 6 to 8 weeks throughout June and July, and gradually changing to a tan color to provide interest throughout fall and winter.
‘Annabelle’ remains one of the most popular cultivars of our native smooth hydrangea, Hydrangea arborescens, appearing throughout the eastern U.S. in landscapes from zones 3 to 9. Despite its national-level popularity, the ‘Annabelle’ hydrangea has roots very close to home, with origins in Illinois.
Smooth hydrangea makes an excellent landscape plant, not only for its beauty, but also for its adaptability. It prefers partial shade but does well in full sun with sufficient soil moisture. While it prefers a rich, moist, well-drained soil, it will tolerate a wide range of conditions. It can work in a variety of landscape applications from a single specimen to a border or mass planting,
The story of the ‘Annabelle’ hydrangea begins in Southern Illinois near Anna. In 1910, Harriet Kirkpatrick noticed a beautiful native hydrangea along a wooded trail in Union County with abnormally large, snowball-like blooms, which she dug up and transplanted in her yard in Anna. Neighbors and friends noticed the showy plant, and the Kirkpatrick family shared specimens, distributing it around town and in nearby communities.
Given its local popularity, easy transplanting and culture, Kirkpatrick contacted the Burpee Seed Company to see if there was interest in developing it commercially. Unbeknownst to her, a recent improved cultivar of Hydrangea arborescens had just been released in 1906. E. G. Hill brought the ‘Snowhill’ hydrangea into production from a wild specimen found near Yellow Springs, Ohio, with similar abnormally large, snowball-like flowers, but an earlier bloom time.
For the next 50 years, ‘Annabelle’ was an unnamed, but locally popular cultivar. It was distributed by word of mouth throughout Southern Illinois until finally reaching Urbana around 1935, based on the first recorded account.
It wasn’t until the 1960s that the Kirkpatrick’s find gained the attention of University of Illinois professor Dr. Joseph C. McDaniel. In 1960, McDaniel rediscovered ‘Annabelle’ by noticing it in cultivation in Urbana. He traced it back to Anna, collected samples for propagation, named the cultivar and released it for commercial production in 1962. The name ‘Annabelle’ is a nod to the “belles” from Anna that originally discovered the wild specimen. McDaniel called it, “the best form of its species yet found.”
Drought tolerant plants for the landscape
By Gemini Bhalsod, Extension Educator, Horticulture
It can be a challenge to choose plants that survive Illinois’ changing weather patterns. While we can go inside and enjoy the air conditioning, our plants don’t have the same luxury.
Illinois summers can get hot and dry, so it’s important to choose plants for your landscape that can survive those conditions. You can even consider planting a specific drought tolerant garden using this list of plants. Be sure to check if there are other varieties or cultivars suited for your area. As summer progresses, watch for symptoms of prolonged drought stress like stunted growth, curling leaves, leaf drop, leaf scorch, and chlorosis.
Drought tolerant plants
- Hackberry, Celtis occidentalis: This 40- to 70-foot tall tree grows in zones 2 to 9 and flowers in the spring.
- Purple Beautyberry, Callicarpa dichotoma: This 4-foot-tall deciduous shrub grows in zones 5 to 8. It is known for its beautiful purple fruit in the fall.
- Red Twig dogwood, Cornus sericea: This 7- to 9-foot shrub is best known for its striking red twigs in the winter. It grows in zones 2 to 7.
- Big Bluestem, Andropogon gerardii: A quintessential Illinois plant, this grass grows 4 to 6 feet high and tolerates dry conditions in zones 4 to 9.
- Side-oats Grama, Bouteloua curtipendula: This grass grows 2- to 2.5 feet high in zones 3 to 9. It is known for its seed heads for winter interest.
- Rock Cotoneaster, Cotoneaster horizontalis: This trailing shrub is often used as a ground cover. It grows in zones 5 to 7.
- Yarrow, Achillea millefolium: This 1- to 2-foot perennial grows in zones 4 to 8. Its feathery leaves help bring dimension and texture to an ornamental garden.
- Blue false indigo, Baptisia australis. This 3- to 4-foot tall perennial grows in zones 3 to 9. Its blue flowers bloom in the spring.
- Purple Coneflower, Echinacea purpurea: This herbaceous perennial grows to 2 to 4 feet in zones 3 to 8. This plant is a favorite of birds and has winter interest due to its long stems and prominent seed heads.
- Bundleflower, Desmanthus illinoensis: This plant grows 2- to 4-feet in zones 5 to 8. It blooms June through August and the flowers appear as fuzzy balls due to the long stamens.
Growing irises: How to plant, grow and care for iris
By Jennifer Fishburn, Extension Educator, Horticulture
There aren’t very many plants that come in a wider range of color than iris. In the past 50 years, thousands of cultivars in various colors, sizes, and forms have been developed. I have about 20 cultivars of bearded iris in my garden including a small white and lavender variety that has been passed down in my family for four generations.
Types of iris: Iris are divided into three categories: bearded, beardless, and aril, according to The American Iris Society. Many types are long-lived perennials in Central Illinois. Iris range in height from 6-inch-tall dwarf crested iris to 5-feet-tall yellow flag iris.
Flower color: The six-petaled flowers come in a rainbow of colors include pink, varying shades of purple, pale yellow, bright yellow, peach, pale green, light blue, white, tan, bronze, almost black, and bi-color. The three inner upward true petals of iris are called “standards.” The three outer turned down flower petals are referred to as “falls.” Many cultivars have different colored standards and falls. Be sure to remove old blooms after flowering.
The most common variety is bearded iris. These easy-to-grow iris range in height from 18 to 36 inches. Bearded iris also vary in bloom time and flower color. It grows best in well-drained soil in a full sun location. It will not tolerate poorly drained soil.
Pests and diseases: Bearded iris do have a few problems including iris borer, bacterial infections including bacterial soft rot and fungal infections of the rhizomes, leaf spots. Imagine my disappointment last year when I noticed several of my iris plants looking rather frail. Upon closer inspection I found that the rhizomes had turned to mush from bacterial soft rot. This bacterium needs a wound to enter a plant. Iris soft rot is often enters wounds caused by iris borers. Proper sanitation is important, remove and discard infected rhizomes and plant parts.
Iris borers are destructive and difficult to control. They can infest all types of iris. For more information on iris borer visit University of Minnesota Extension.
Planting and dividing: Most iris clumps become crowded and should be divided every three to four years. About four to six weeks after they flower, divide by digging up the whole clump and remove the mother plant.
Place the rhizome on a ridge of soil, placing the roots in the soil, but the rhizome just above soil level. Space rhizomes 12 to 18 inches apart to avoid overcrowding and allow for good air circulation to help prevent disease issues. Since iris have a short bloom period, consider adding iris in the middle of a perennial garden where later blooming plants can hide the iris foliage.
Learn more about various species and cultivars of iris by visiting the Missouri Botanical Garden website.
When to prune hydrangeas
By Ken Johnson, Extension Educator, Horticulture
Hydrangeas are popular shrubs grown for their impressive blooms. Their foliage can also be attractive, particularly oakleaf hydrangeas. Pruning hydrageas can be confusing because each species should be pruned at a different time of the year.
Five species of hydrangea are commonly found in cultivation. These can be divided into two groups for pruning purposes: those that bloom on old wood and those that bloom on new wood.
Old wood blooms
Hydrangeas that bloom on old wood start to develop their flower buds for the following year in August and September. Therefore, if you are going prune, try to do it as soon as possible after they are done blooming and by August 1 at the latest. By doing this, you will avoid removing any of the developing flower buds.
The three commonly cultivated Hydrangea species that flower on old wood are:
- Hydrangea macrophylla, which are commonly called bigleaf, mophead, and lacecap hydrangea.
- Hydrangea quercifolia, which are also called oakleaf hydrangeas.
- Hydrangea anomala, also called climbing hydrangea.
There are some varieties of H. macrophylla that are reblooming or remontant, meaning these cultivars will produce on both old and new wood. If buds are damaged or killed during the winter, the plant can still ﬂower on new wood. Examples of these types of hydrangeas are the Endless Summer, Let’s Dance series, and Tuff Stuff hydrangeas.
New wood blooms
Hydrangeas that bloom on new wood produce their flower buds on the current season’s wood. These plants can be pruned from late winter to early spring. They can be, and are commonly, drastically cut back in the fall. Repeatedly doing this can weaken the plant, though. Consider pruning every other year or every three years to maintain plant health and vigor over time.
The two commonly cultivated hydrangea species that bloom on new wood are:
- Hydrangea paniculata, commonly called panicle or PG hydrangea.
- Hydrangea arborescens, commonly called smooth hydrangea.
More drastic pruning – size reduction, thinning, etc. – is different than the routine maintenance pruning that can be done at any time. Maintenance pruning helps maintain a plant’s shape, vigor, and health, and includes removing diseased and dead wood as well as deadheading spent flowers.
Perennial Favorite Named Plant of the Year
By Martha Smith, Extension Educator – Horticulture
The Perennial Plant Association is proud to announce the 2020 Perennial Plant of the Year®: Aralia ‘Sun King’! This fabulous, high-impact perennial brings a bold pop of glowing color and texture to the shade or part-shade garden. Aralia ‘Sun King’ also won the International Hardy Plant Union Outstanding Plant Award in 2012.
Native to shady, forested areas in Japan, Sun King was discovered by plantsman Barry Yinger in a Japanese garden center. This perennial has become a beloved shade garden staple across the country. Bright yellow shoots emerge in spring, then grow upwards to 4-6’ tall and nearly as wide. The small, cream-colored umbels of flowers appear in late July through September, are attractive to bees, and are followed by tiny, dark (inedible) berries. This is a very well behaved plant with little reseeding or suckering.
Place Sun King where you want height. It is fast growing, filling a background space all season long. Hardy to USDA zones 3-9 (Northern Minnesota to Gulf of Mexico) it’s hard not to find a place in the garden for this gold-leaf beauty. To retain this color, place in partial shade; if in heavy shade, the color becomes more lime green. It will tolerate more sun as long as ample moisture is provided. During long periods of drought, Sun King will suffer if not kept watered. Being herbaceous, it will die back in the fall and re-emerge in the spring. It is best grown in well-drained soils and benefits from compost being incorporated. Sun King has no serious insect or disease problems, and deer don’t bother it.
Also called Udo, Japanese asparagus, Mountain asparagus, or Japanese spikenard, young shoots of this plant are considered a culinary delicacy in Japan, where they are cultivated in underground tunnels. The flavor is reported to taste asparagus-like, or lemony. Young shoots are blanched or pickled. White, fleshy roots are eaten as one would consume a parsnip.
Sun King is terrific in combination with hostas, ferns and past PPOY stars, such as Heuchera ‘Palace Purple’ (1991), Brunnnera acrophylla ‘Jack Frost’ (2012), and Polygonatum odoratum ‘Variegatum’ (2013). It’s a knockout when placed near Acer palmatum ‘Bloodgood,’ or other maroon-leaf plants. And, don’t forget containers—Sun King is bold and beautiful in a big pot!
This low-maintenance perennial benefits from a pinching, or slight cutback in May to encourage branching. It truly meets the criteria set by the Perennial Plant Association to be awarded the Perennial Plant of the Year®. The PPOY program began in 1990 to showcase a perennial that is a standout among its competitors. Perennials chosen are suitable for a wide range of growing climates, require low maintenance, have multiple-season interest, and are relatively pest and disease-free.
Why You Should Think About Sequence of Bloom
By Andrew Holsinger, Extension Educator - Horticulture
Sequence of bloom describe when a plant is expected to bloom. Planning for the sequence of bloom is a great way to keep your garden attractive all year round. Flowering is only one aspect of a garden, but the amount of bloom can boost your garden’s appeal substantially. While the influences of nature vary from year to year, the sequence of bloom remains the same.
Encouraging successive blooms throughout the year has many benefits beyond visual appeal. Continual bloom adds a source of food for pollinators and provides a level of interest each season. It increases the spread of fruit availability when thinking about edible landscaping. The sequence of bloom is also a great marketing strategy. A forecast of what’s in bloom draws interest and a garden feels more dynamic when there is constant, evolving change.
Plant selections based on sequence of bloom can be maximized for impact. Distribute blooming plants uniformly around the garden to elevate the level of bloom overall. Keep in mind, proper site selection is critical in providing the best environment for successful flowering.
Planning a garden with sequence of bloom in mind doesn’t have to be complicated. Focusing on the timing of what’s in bloom at an approximate time of the year can help you develop a strategy for planting. But there are other strategies to consider when selecting new plants for your garden.
- Compile a list of what you already have blooming.
- Evaluate your hardiness zone for what will thrive.
- Reference each plant’s approximate time of bloom.
- Match layers of bloom with the landscapes’ visual height.
- Develop a color scheme that enhances your selections.
- Think about purpose and how your design choices are influenced by it. For example, do you want plants that will provide a pollinator food source?
- Consider how long your plant selection blooms. Period of bloom can also influence your choices.
- Select new plants that will complement the existing elements and timing of your garden.
If you are a visual thinker, there are a few ways to organize the sequence of bloom for different plant combinations on paper. A Gantt chart helps create a view of scheduled tasks or events over a designated period of time. This type of chart would be great for visualizing the blooming sequence. Color-coding can also present an easy, quick reference for what plants might work to optimize your space.
The next time you visit a garden, pay close attention to what’s in bloom and how it contributes to the overall impact of the garden. Considering the sequence of blooms in your planting strategy will help you to create a more robust garden full of visual beauty throughout the year.
Designing a Sensory Garden
by Brittany Haag, Extension Educator - Horticulture
Sensory gardens are areas designed to stimulate one or more of the five senses: sight, smell, sound, taste, and touch. While often geared toward young children, sensory gardens can be enjoyed by all ages. They can also be therapeutic for individuals with developmental or physical disabilities, sensory processing disorders, or cognitive challenges. While exploring any garden, you are already connecting with some of your senses, but a sensory garden has a more mindful approach by including and arranging specific plants to engage the senses.
Contrasting color, texture, light, shadow and form in the garden can all stimulate our sense of sight. Warm colors, like red, orange and yellow, are energizing, while cool colors, like blue, purple and white, are relaxing. The plants selected should be both stimulating and calming. Bright mixes of garden zinnias (Zinnia elegans) or giant yellow sunflowers (Helianthus annuus) towering above the garden make for an invigorating pop of color, and both will attract beautiful butterflies to the garden.
Smell is often the strongest human sense, with the potential to bring back specific memories and experiences to individuals. Some plants release scent naturally without the need for touch (roses), while others do not release a scent until they are rubbed or crushed (geranium). Catmint (Neptea mussini), a hardy perennial that produces pale purple flowers from May to September, releases a light lavender-like scent when the leaves are rubbed.
Some sounds in the garden occur naturally—wind blowing through the plants, or leaves crunching beneath our feet. Wind chimes and water fountains can add a calming sound, as well. Bird feeders and baths can attract our feathered friends to visit the garden to play their song. Ornamental grasses, like switchgrass (Panicum virgatum), rustle in the wind. Dried seed pods on false blue indigo (Baptisia autralis) can make natural maracas as the seed rattles against the hard pod.
A variety of fruits, vegetables and herbs can be added to a sensory garden to explore tastes. Edible flowers, including nasturtium and pansy, also make tasty additions. Be sure to clearly identify which plants in the garden are edible.
A variety of textures to explore, including rough, smooth, fuzzy and even sticky, should be offered through plant bark, foliage, flowers, seeds, and fruits. Tough plants that can withstand frequent handling should be selected. Lambs ear (Stachys byzantine) is a favorite fuzzy-leaf plant to include.
Just like with any garden, select plants that are hardy to your area and of various color, height, textures, and bloom times. To ensure safety in the garden, plants should be non-toxic and pesticides should not be applied. A sensory garden is a great place for anyone to explore their senses and to learn about nature and plants.
by Nicole Flowers-Kimmerle, Extension Educator - Horticulture
Do you enjoy watching bees buzzing around your flowers, butterflies resting in the sun, or a fat toad sitting in a shady spot? Making your garden wildlife-friendly starts with knowing what will attract birds, insects, and animals to your yard. Wildlife needs water, a food source, shelter, and space. Small changes in your garden habitat can make a big difference to the wildlife you wish to attract.
One way to attract wildlife to your garden is to add a water source, like a birdbath. To maintain a healthy environment for your wildlife, be sure to clean your birdbath two to three times per week. It’s important to thoroughly rinse away all cleaning products from the birdbath before refilling it with clean water and allowing animals to use it again. Birdbaths are not the only option, though. A water source can be as simple as a rock with a depression that holds water.
Another thing to consider for a wildlife-friendly garden is a food source. When it is time for fall clean up, consider leaving seed heads on perennial plants, which can be a food source for birds. Leaf litter and hollow stems can provide overwintering sites for many beneficial insects and pollinators. Plants that flower early offer a food source for those insects as they become active in the spring. Make sure that your garden includes a variety of plants, so that there are blooms from early spring to late fall. Increase the variety of butterflies by providing food for their larvae. Plants from the carrot and aster families are great options. Plant extra dill or parsley, and you may see more swallowtail butterflies in your garden.
It’s important to remember that as you provide an attractive habitat for wildlife, pests may also find your garden. Not to fear, though! Insect predators and parasites, attracted to the variety you’ve created, will move in and help control those pests. Insect-eating birds will find their way to your garden if their preferred food becomes more abundant. Some organic farms even include birds as part of their pest management plan. Keep in mind that there will be a lag time between the pests showing up and the beneficial creatures doing their job to decrease the population. Just be patient and trust that they will take care of those pests for you in due time.
Shelter is the third important component of a wildlife-friendly garden. Provide shrubs and trees that vary in height for housing all types of animals. Consider creating a toad house by turning over a terra cotta pot and propping up one side to create an entrance. Toads are another creature that will help control insect pests.
Finally, sit back and enjoy the wildlife that is visiting your garden. Recording your observations in a nature journal is a fun way to spend time in your garden with the added bonus of helping you track how your garden and its wildlife inhabitants change from year to year.
Soil Temperatures for Spring Planting
by Chris Enroth, Extension Educator - Horticulture
Most gardeners understand that seeds germinate in warm soils. Sow your tomato seeds too early in the spring when the ground is still cold and you may get little to no germination. My favorite saying is, “When you can sit comfortably on the ground bare-bottomed, it’s time to plant your garden.”
Luckily, there are more reliable ways to monitor your soil temperatures. Soil thermometers are a simple and cheap tool for keeping track of the soil temperatures in your yard and garden.
Knowing your soil temperature is important because it tells you when you can put seeds in the ground. Seeds have a germination window of soil temperatures. Yes, you can germinate Romaine lettuce at 35 degrees Fahrenheit, but this will lead to slow plant development. Romaine’s optimum soil temperature for germination is usually around 70 degrees.
Keep in mind that when growing outdoors, those warmer soil temperatures come with hotter weather, which could be stressful to vegetables. Waiting to plant your greens until your soil is 70 degrees, may be too late in the growing season. Seed packets, catalogs, or the supplier’s website will tell what you need to know about when to plant flowers and vegetables.
Influences On Soil Temperature
The first major influence on your soil temperature is its exposure to the sun. Photons of sunlight travel the vast distance of space into our atmosphere, striking the surface of the Earth. Much of that light energy is transferred to heat energy and radiates back out toward space or is absorbed by the soil. The surface of the soil heats up at the beginning of the day and cools off at night. Lower layers of soil warm by convection from the top surface. This means they warm up slower, but hold their heat longer. When sowing seeds, monitor the soil temperature at whatever depth you will be planting the seeds.
Soil type and moisture also play a role in soil temperature. Sandy soil is very well-drained. This allows the surface to heat and cool rapidly. Think about walking on a hot sand beach. Bury your toes a little in the sand and you get some relief from the hot surface. Clay soils can hold a lot of water, which means it takes more solar energy to warm them up; once warm, though, clay soil tends to hold that heat longer. Many gardeners with heavy clay soils find it takes much longer in the spring for their ground to warm up, which may prolong seed germination.
Manipulating Soil Temperature
Gardeners anxious for spring may use techniques to increase their soil temperature and get a jump start on planting.
- Site your garden in a south-facing exposure. Exposure to sunlight has the biggest influence on soil temperatures.
- Use sheets of plastic or fabric mulches to trap heat at the soil surface. Clear plastic will allow sunlight in but trap the heat. Keep in mind, though, this may also hasten weed growth. When using fabric or row covers, remove them during sunny days and replace them at night.
- Construct raised beds, which warm up quicker in the spring. This can be a good tool for gardeners with heavy clay or contaminated soils.
- Lightly till to break up the soil surface and encourage drier soils that heat up faster. Be mindful that dry soils will also cool quickly and that tilling cold, wet soils can create compaction and clods.
- Create a completely artificial germination chamber by starting plants indoors using heat mats and lighting. Hold them indoors until the soil and air temperatures are conducive to their growth.
Protecting Tender Plants from Spring Frost
By Austin Little, Extension Educator – Horticulture
The long winters of the Midwest can give gardeners false hope that spring has arrived, depending on Punxsutawney Phil’s weather forecast. In early spring, many cool-season annuals and perennials are breaking dormancy and starting to bloom well before the threat of frost has passed. Rather than relying on a rodent’s prediction, there are several easy practices that protect vulnerable plants from unpredictable spring frost.
To protect tender buds from a light spring freeze, one of the best defenses is to cover the plants. The covering acts as an insulation layer that helps to hold warm air radiating from the ground and adds protection from cold, dehydrating winds. There are many types of coverings for plants. For smaller annuals and perennial plants, a simple cardboard box, sack, or pot could do the trick. The French have used cloches (small glass coverings) for frost protection since the 1600s. Cloches can be thought of as temporary, miniature greenhouses.
For small shrubs, a large bucket or blanket can be used. While it may not be pretty, it gets the job done. I have seen my dad use sheets to save his prized azaleas on several occasions. Small trees, such as fruit trees, and larger shrubs may pose a bit more of a challenge. One option is to use large, fleecy, white row cover fabrics that act as a great insulator, but will need to be anchored with something heavy, or pinned to the ground.
Another surprising, yet effective measure against spring frost is water. This may seem counterproductive, but due to the unique chemical properties of H2O, as it freezes on the surface of foliage, it actually releases heat as the water changes from a liquid to a solid. Spraying larger shrubs and small trees with a coating of water before a freeze can help save flowering buds. On a smaller scale, watering the root zones of smaller plants can also be effective. Plant cells that are well hydrated are able to buffer temperature changes more effectively. The same is true for an evenly wetted soil compared to a dry soil. One caution is to make sure the temperatures will be above freezing the next day to avoid more damage than would otherwise occur.
With these practices, it may be possible to save many tender buds from occasional spring frosts and get the most out of those much-appreciated, early spring blooms.
Download This Issue of the Newsletter
Download, save, and share the Volume 15: Spring 2020 issue of the newsletter.
© Copyright 2020 by the Board of Trustees of the University of Illinois. For information on duplicating or linking to this material, please contact firstname.lastname@example.org. Commercial uses are prohibited.
University of Illinois • U.S. Department of Agriculture • Local Extension Councils Cooperating. Issued in furtherance of Cooperative Extension Work, Acts of May 8 and June 30, 1914, in cooperation with U.S. Department of Agriculture. Shelly Nickols-Richardson, Director. University of Illinois Extension provides equal opportunities in programs and employment.