In German, kohlrabi means “cabbage turnip,” referring to the fact that it is in the cabbage family but forms an edible turnip-like bulb just above the soil line. Not truly a bulb, it is an expanded stem, and looks like it house aliens that have flown it in from out of space. Nutritious and cold hardy, a must grow, though most Germans would disagree.  When to Plant Zone 1: August - February Zone 2: July - March Zone 3: February - September Zone 4: March - May For zone map CLICK HERE Soil  Prepare your soil in a similar manner to that of growing carrots. They prefer a deep, friable soil type that is not overly rich with nitrogen. Will require high levels of potassium so applying potash and mulching with lucerne hay is recommended.