Kale, a non-heading form of cabbage, originated in either the Mediterranean area or Asia Minor over 2000 years ago where it was cultivated as an important food source. Greeks and Romans grew a variety of cabbage-like vegetables before the Christian era. Although many cultivars of cabbage have developed with years of cultivation, kale and collards remain unchanged as a primitive form of cabbage. These cold season greens are high in nutritional value and prized for their texture and flavor.
Harvest Kale when leaves develop a firm texture and lighten in color. Dark heavy leaves, much like the outside leaves of a cabbage, are tough and lack flavor. Kale matures 50 to 65 days after direct sowing or about a month from setting out transplants.
Pick young leaves for use in garden salads throughout the summer, but wait until the first two or three frosts to harvest mature leaves for greens. Frost enhances the flavor as it converts carbohydrates to sugar giving them a delicate sweet flavor.
Cut the outside leaves and allow inner leaves to mature. Cutting a few leaves from each plant extends the harvest and provides fresh kale for weeks. Alternately, you can harvest the entire plant by cutting at the base.
Mulch with straw or hay after the first few frosts. Although cold weather enhances flavor, kale cannot grow in freezing soil and should be harvested before a freeze. Kale continues to produce into late fall and early winter when protected from freezing.