Kohlrabi has pale green, cruciferous bulbs and edible leaves that grow above the ground. The tender, white flesh has a mild flavor and can be enjoyed raw, roasted, or steamed. Many compare its creamy flavor to turnips or cabbages.
White Vienna originated in the 19th century. Kohlrabi has been grown in Germany, England, Italy, and Spain since the 1600s.
Start seeds indoors in flats three to four weeks before transplanting to the garden. Transplant seedlings one week after the last spring frost, being careful not to disturb the roots. Keep soil moist and fertilized throughout the growing season.
Kohlrabi leaves should be harvested while the plant is young and tender. The stem is best harvested when bulbs become full and globe-shaped (2–3 inches diameter). Use a sharp knife to cut the bulb at ground level.
Before the first frost, dig up the entire plant, roots and all. Trim off outer leaves but keep the growing point intact. Replant these trimmed plants in containers filled with slightly moist potting mix or sand. Then, find a place (like a garage or shed) to store your plants where temperatures remain between 34–39ºF. In the spring, replant kohlrabi plants in your garden when the soil can be worked. Plant them about 36 inches apart. Flowers will emerge and dry. Harvest dried flower pods and leave on a cloth to dry fully. Roll the pod in your hands to crack open the skin and reveal seeds. Separate seeds from the chaff and store in a cool, dry place for up to four years.