Growing Leafy Greens in the Home Garden
Guidelines for growing leafy greens in your home garden are offered by Maurice Ogutu, U of I Extension horticulturist.
Leaves are the edible parts of most leafy green vegetables, explained Ogutu. "The leaves of some leafy greens are cooked and others are eaten fresh as salads," he explained. Some of the commonly grown leafy greens are collards, kale, lettuce, spinach, turnip greens, and Swiss chard. However there are some popular specialty leafy greens such as mustard greens, arugula, cress, mache, dandelion, and Asian vegetables. Leafy greens are becoming more popular in home gardens."
Leafy greens have similar cultural requirements when grown in home gardens. Collards and kale (Brassica oleracea L.) belong to the same group as cauliflower, cabbages, broccoli, and kohlrabi but in a sub-group that is called Acephala (non-heading types). They are cold-tolerant and leaves are usually cooked before eating.
Lettuce (Lactuca sativa L.) is a plant in the daisy family and it can be eaten raw or cooked. There are three types of lettuce – leaf, head or romaine, and Boston or Bibb. Leaf lettuce grows fast and is easy to grow in home gardens in Illinois.
"The head and Bibb lettuce can also be grown but need more care in order to get a good crop in Illinois," he said. "Lettuce is a cool weather crop that does well at temperatures around 63 degrees F and becomes dormant when it is too hot."
Spinach (Spinacia oleracea L.) is a plant in the Amaranth family. The leaves can be smooth or ruffled in texture. It is a cool season cold-tolerant vegetable that tends to form a flower head when it is too hot. Turnip greens (Brassica rapa L.) is a plant in the Chinese cabbage group and varieties grown for leaves have small or no storage roots. It is a cool season vegetable that performs well in cool weather. Swiss chard (Beta vulgaris L.) is related to beets, leaf blade and petioles are edible and there are varieties with white, pink, gold, orange, and red stems.
"Mustard greens (Brassica juncea L.) sometimes referred to as leaf mustard has a distinct pungent flavor," Ogutu said. "The leaves and stems are edible and it is used in Asian and African cuisines including preparation of soul foods. It is easy to grow and grows very fast." Arugula (Erica sativa Mill) is an annual plant native to the Mediterranean region. It looks like a longer leaved and open lettuce.
Ogutu recommended planting leafy greens in a location with full sun, fertile-well drained soil, and near a water source. Test your soil. For more information about soil testing labs in your area contact the local Extension office.
Apply well-rotted manure or compost and incorporate into the soil. If the soil test is high in phosphorus, consider using low or no phosphorus fertilizers. The greens require soil pH 6.0-6.5 except for spinach that requires soil pH of 6.4-6.8. Apply three pounds of a complete fertilizer such as 10-10-10 per 100 square feet and side dress once with one pound of 10-10-10 per 25 feet row two to three weeks after transplanting or plant emergence in soils that were tested during the last two years. Do not use fertilizer containing weed killer. Practice crop rotation to reduce incidence of soil-borne diseases.
Leafy greens are direct seeded except kale, collards, lettuce, and Swiss chard that can be transplanted. The seeds can be started indoors at least four weeks before transplanting (that is in late March/early April). Harden seedlings by exposing them to outdoor environment gradually two to three days before transplanting.
Transplant kale and collards eight inches apart, leaf and Bibb lettuce eight to 12 inches apart, head lettuce 10-12 inches apart, and Swiss chard four to six inches apart in rows 18 inches apart.
Direct seed collards, kale, lettuce, and spinach as soon as the ground can be worked in early spring and at least two to three months before the fall frost date. Plant seeds one-fourth to one-half inch deep in rows that are 18 to 30 inches apart. After plant emergence, thin collards, kale, leaf lettuce, and Bibb lettuce to eight to 12 inches apart.
Thin Swiss chard to four to six inches apart and spinach to two to four inches apart. Spinach can be planted every one to two weeks until outdoor temperatures reach 80 degrees F for continuous harvest during the growing season.
Control the weeds by hand pulling or cultivation but do not dig deep close to the base of the plants to avoid root injury. Leafy greens can also be mulched with a three to four inches thick layer of herbicide free grass clippings, or weed-free straw to retain soil moisture and suppress weeds.
"Leafy greens are shallow rooted hence they need one inch of water per week based on the amount of rainfall recorded in a week," Ogutu said. "They can be watered using watering cans, soaker hoses or sprinkler irrigation.
"Water plants in the morning so that leaves dry up during the day time in order to minimize incidences of foliar diseases. Higher watering frequency may be needed in sandy and sandy loam soils compared to clay or clay loam soils."
Aphids can be a problem in leafy greens, and they can be controlled by hosing leaves when watering, and by natural enemies like ladybird beetles. Cabbage worms and flea beetles may also damage plant leaves. To prevent such damage, cover the plants with floating row covers when moths and flea beetles are seen flying in the garden.
Cercospora leaf spot that causes circular yellow spots on leaves of Swiss chard, collards, and kale is one of the common diseases. Remove infected leaves from the garden and avoid using overhead irrigation. Refer to these web sites for more information on insect pest and disease control: Common Vegetable Problems: http://urbanext.illinois.edu/vegproblems/ and Common Diseases of Leafy Greens: http://www.aces.edu/pubs/docs/A/ANR-1189/.
Harvest single leaves when they reach usable size. Discard any diseased, bruised or yellow leaves. Harvest collards by removing the outer leaves, spinach by cutting dark green outer tender leaves that are three to six inches long, and Swiss chard by removing outer leaves. "Harvest by removing outer leaves of kale, mustard greens, and turnip greens," he said. "Wash the leaves before storage, use in a salad or cooking."