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.
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