Family: Brassicaceae
Genus and Species: Brassica oleracea

Climate

Kale grows best in cool climates and will benefit from a fall frost. Cold days and nights sweeten kale while hot weather produces bitter tough leaves.

Soil

Kale grows best in cool moist soil that is enriched with compost. Optimal soil temperature for growing kale is between 60°-65°. Kale does best when pH of the soil is between 5.5 and 6.5. Kale requires moderate amounts of nitrogen, phosphorus, and potassium.

Spacing

If you plan to harvest the kale leaves at their youngest stage plant kale 8"-12" apart in rows 18-30" apart. Young leaves are great for salads.

An alternate spacing is to give the kale plants more room to grow using a 16" spacing. This spacing allows for good air circulation and will allow the kale to grow longer without harvest. Older leaves are good for cooking but are too tough for salads.

Direct Seeding

In cool climates direct seed kale as soon as the soil can be worked in the spring. Kale germinates in soils that are 45°-95°. In warm climates plant kale seeds in early spring or in late summer or early fall for growing during the winter months. Plant the seeds 1/2" deep in prepared beds. Make sure the seeds do not dry out before germination.

Seeding For Transplants

Kale can be started indoors 6 weeks before the last frost. Start seeds in seed flats in a good growing mix. Place plants under grow lights if available.

Germination

These seeds germinate best in soils around 65°F-85°F.
Germination will take 5-7 days.

Transplanting Into the Garden

Transplant kale to the garden making sure that the soil is enriched with compost and moist. Plant kale with 8"-16" between plants in all directions.

Watering

Kale produces sweet, crisp leaves if soils are kept moist. Kale does not like to dry out. Using straw mulch around the plants helps retain soil moisture but kale does need to be watered regularly throughout the growing season.

Harvesting

Kale can be harvested as soon as the leaves are ready to be used although the leaves are most delicious after the first frosts.

Harvest kale by clipping off the outer leaves if you want the plant to keep producing. Or harvest the entire plant when there is a large rosette of leaves.

Post-Harvest Handling

Wash and dry leaves thoroughly.

Storage

Store kale at 32°F with a relative humidity of 95% to 100% to maintain its fresh green color and vitamin content. Store kale with adequate air circulation. Kale should keep for between 14 to 21 days under ideal conditions.

Do not store kale with vegetables and fruits that give off ethylene gas such as apples and pears.

Diseases

Black Rot, Club Root, Fusarium Wilt

Pests

Aphids, Cabbage Loopers, Imported Cabbageworm, Cutworms, Flea Beetles, and Diamond Back Moth

Comments

The trick to producing excellent kale heads is to keep the kale plants growing at a steady pace. Top-dress the plants with compost or manure tea; or side-dress with blood-meal or fish emulsion; and water deeply. Repeat this process every 3-4 weeks until just before harvest.

Mulch will help keep the ground cool and moist as well as reduce weed competition.

References

Bradley, F. M. and Ellis, B. W.(Ed.). (1992), Rodale's All-New Encyclopedia of Organic Gardening: The Indispensable Resource for Every Gardener, Emmaus, Pennsylvania: Rodale Press.

Oregon State University, "Kale, Commercial Vegetable Production Guide", Last modified 2002-12-26, Oregon State University, was at http://www.orst.edu/dept/NWREC/kale.html but is no longer available, Accessed 2003-05-11.

Smith, E.C. (2000), The vegetable gardener's bible: discover Ed's high yield W-O-R-D system for all North American gardening regions., Storey Books: Pownal, VT.