Kale is an archaic type of cabbage that grows loosely furled leaves, rather than forming a head. The leaves of kale have a distinctive ruffly appearance that distinguishes the plant from a close relative, collard greens. Kale tends to be a little bit bitter in flavor, although this bitterness is tempered by washing, cooking, and using younger leaves. Kale is also extraordinarily nutritionally rich, even among the leafy green vegetables.

Kale has been under cultivation for over 3,000 years and was extremely popular in ancient Greece and Rome. In medieval times, kale was sometimes the only vegetable eaten, because it was easy to grow, tolerant to cool climates, and delicious. While kale is less popular than headed cabbage, Brussels sprouts, and other relatives, the plant has numerous merits that are beginning to endear it to consumers again.

Most kale is eaten cooked, although very young leaves may be trimmed from the stalks and used raw in salads. Cooked, kale is mixed in with soups in Portugal, used in mashed potatoes in Ireland, roasted on pizza in Italy, and eaten plain as a side dish all over the world. When cooking kale, be aware that the stems take more time to cook than the more delicate leaves. Some cooks trim out the largest stems to be cooked longer or discarded, to avoid soggy leaves and woody stems.

Kale is rich in calcium, vitamin K, folic acid, magnesium, and beta carotene. Especially for vegans, who are often calcium deficient, kale is a great source of dietary calcium. Kale lends itself to a wide variety of recipes and is delicious sauteed, steamed, grilled, or fried, plain or ornamented with olive oil, salt, lemon, or butter. It can be used as a stand in for other leafy greens, such as spinach in quiche, or added to stir fries and soups.

Kale is an extraordinarily hardy cabbage, suited to gardening in almost any part of the world. It is one of the few greens that takes well to frost, actually tasting sweeter after it has been frost kissed. Kale should not be planted in the summer, because hot weather makes the leaves woody and more bitter. Plant kale in moist, well composted soil approximately ten inches (25 centimeters) apart, and keep the soil moist so that the leaves stay tender and flavorful. Kale will keep for 14 to 21 days if refrigerated and separated from apples, pears, and other fruits that contain the ripening agent ethylene gas.