Brassica oleracea. (55 days) Kohlrabi was first introduced sometime just before the Civil War. Three varieties appeared later in the 1884 D.M. Ferry Seed Catalog. Obviously Kohlrabi has made an impact on gardeners and chefs alike, as it has stood the test of time. Kohlrabi is a member of the cabbage family, but the edible part is actually an enlarged stem. Best harvested when the stem reaches 2-3 inches in diameter. Many people use the young leaves in salads or steamed.