Learn About Kale
Can I grow kale in containers? Yes, but only in a large container 24 inches deep and wide. Be sure to use a commercial container mix rather than garden soil.
Is kale winter hardy? Kale can tolerate frost and temperatures as low at 10 degrees F, and the flavor in fact becomes sweeter when it has experienced frost.
My kale is blooming! Is it alright? Kale can bolt the following spring when it overwinters in your garden. When the temperatures begin to warm it can send up a flower stalk because it is a biennial plant that produces flowers and seed the second year of its life cycle. The leaves will become more bitter when it bolts.
Should I cook kale or consume it raw? Kale may be used raw or cooked.
Should I grow kale in spring or fall? You can grow kale for either season, but a frost will make it taste sweeter in fall.
Common Disease Problems
Bacterial Leaf Spot: This causes brown water soaked spots on the foliage which eventually makes the foliage turn yellow. It thrives in cooler temperatures. Burpee Recommends: Remove infected plants. Rotate crops with plants in a different family. Avoid overhead watering. Do not work around plants when they are wet.
Clubroot: This causes plants to wilt in patches during the day, stunts their growth, and causes swollen or disfigured roots. Burpee Recommends: Rotate crops with plants in a different family. Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Improve drainage by reducing soil compaction. Do not work around plants when they are wet. Control weeds where the disease can overwinter.
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water & rinse in a ten per cent bleach solution after use.
Downy Mildew: This fungus causes whitish gray patches on the undersides and eventually both sides of the leaves. Burpee Recommends: Rotate crops with plants in a different family. Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Do not work around plants when they are wet.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Cabbage Looper: These worms are green with a white stripe on either side, about 1-1.5 inches long. They tunnel through the heads. Burpee Recommends: Hand pick. Floating row covers can help prevent their laying eggs on the plants.
Flea Beetles: These small hopping beetles feed on plant foliage and can spread disease. Burpee Recommends: Rotate crops with plants in a different plant family. Use floating row covers to prevent damage to young foliage.
Leafminers: These insects bore just under the leaf surface causing irregular serpentine lines. The larvae are yellow cylindrical maggots and the adults are small black and yellow flies. They do not usually kill plants, but disfigure the foliage. Burpee Recommends: Remove affected foliage.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Harvest and Preserving Tips
- Harvest kale after first frost if you prefer a sweeter flavor.
- Pick the outer leaves as needed once they reach 6-8 inches long about 55-60 days after transplanting.
- Leave the central bud since it will grow new leaves.
- Store kale in an airtight bag in the refrigerator for 5-7 days. Wash when ready to use.
- Use kale as a substitute for lettuce, cooked cabbage and collards.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating. Avoid disturbing the soil around the plants when weeding.
- Keep plants well watered during dry periods to promote rapid, uninterrupted growth.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area. While small, floating row covers will help to keep pests at bay.
How to Sow and Plant
Kale may be direct sown for a spring and fall crop, or purchased as transplants for a fall crop.
Sowing Directly in the Garden:
- Sow in full sun in early spring and in midsummer for fall crop.
- In the Deep South, gulf, and pacific coast areas, sow from fall to early spring.
- Plant seeds evenly and thinly and cover with ¼ inch of soil.
- Firm lightly and water gently.
- Seedlings emerge in 10-21 days.
Planting from Transplants in Fall:
- Kale prefers rich, well-drained soil, and can tolerate some shade. Avoid areas where any member of the cabbage family grew the year before.
- Prepare the bed by turning the soil under to a depth of 8 inches. Level with a rake to remove clumps of grass and stones.
- Dig a hole for each plant large enough to amply accommodate the root ball. Space plants 1 – 1½ feet apart in rows 2 feet apart.
- Carefully remove the plant from its pot and gently loosen the root ball with your hands to encourage good root development.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand.
- Thoroughly water and apply a light mulch layer on top of the soil (1-2 inches) to conserve water and reduce weeds.