Resource Library
Plant of the Week: Kale, Curly Leafed
The University of Arkansas System Division of Agriculture does not promote, support or recommend plants featured in "Plant of the Week." Please consult your local Extension office for plants suitable for your region.
Plant of the Week
Curly Leafed Kale
Latin: Brassica oleracea Acephala
In the beginning, there was kale. From it arose the others; cabbage, broccoli, cauliflower, Brussels sprouts, mustard and collards.
The accessorial form of kale originated in Asia Minor and the eastern Mediterranean region where it has been cultivated for more than 4,000 years. The Romans are credited with much of the early history of this important vegetable - especially the cabbages - but their writings are what survived into the modern age; undoubtedly this nutrition-rich food has been with us much longer.
Botanically, kale is Brassica oleriaceae var. Acephala; the variety name means "without a head." It's a cool season biennial capable of growing two- to three feet tall with thick, usually crinkled (savoy), broadly linear 18-inch long leaves borne up the stalk at a 45-degree angle.
Kale leaves have a waxy coat and are usually offered in shades of gray-green or purple.
Collards, a closely related type and the greens of choice in the southern United States, have green, more spatulate leaves with little or no crinkling.
Kale flowers during the spring, but to do so must have gone through the winter without being killed by freezing temperatures. Flowers, while not the reason to grow kale, are produced at the ends of the elongating stem as the plant bolts in mid-spring. Blooms are from light to dark yellow, about the size of a dime and consist of the four petals typical for all members of the mustard family. Seeds are produced in an elongated seed capsule. As the seeds mature, the plant dies.
Americans know kale well, though few eat it. It's primarily used to adorn the self-service salad bars across the land, displacing other green adornments because of its resistance to wilting. As a vegetable, it's near the top of the list in terms of nutritional value, containing heart-healthy antioxidants such as beta-carotene, large amounts of vitamins A, C and E and heavy doses of calcium, potassium and iron.
Kale's sweetness is brought out after a series of frosts which help break the starches into sugars. The leaves take on a strong flavor if stored longer than two weeks in the refrigerator, so picking as need ensures the best flavor. Strip the lower leaves from the base of the plant as needed. Leaf removal encourages new growth and insures a prolonged harvest. It is ready for harvest in two months from planting. Good gardeners harvest about one pound of kale leaves per foot of row, so keep that in mind when deciding how much to plant.
Of late, purple leafed kales such as Redbor or Red Russian have gained prominence in flower beds where they are used as a winter annual along with pansies and dianthus. It will tolerate temperatures as low as 10 degrees to 15 degrees without injury. It may survive even lower temperatures, but the foliage will be severely burned. Transplants can also be planted in late winter and grown as an accent for spring bulbs.
Kale is not finicky about soil types, but like most garden vegetables grows best in sunny, well drained and fertile soils. Spring plants can go out six weeks before the frost free date. In the fall, transplants should be set out in late August. Kale can also be seeded directly into the garden; the fall crop should be planted in August; the spring crop by late February. Cabbage loopers, the caterpillar form of an inch wide, flighty moth, feed on kale but are not as destructive as on cabbage.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - April 13, 2007
The University of Arkansas System Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.