Brassica oleracea gongylodes
Also known as the turnip cabbage, kohlrabi is a form of cabbage grown for its edible swollen stem, which has a turnip flavour. The stems may be cooked or grated raw for use in salads. Kohlrabi withstands drought better than turnips, so it is a useful crop in warm, dry areas, although the most succulent stems will be produced with plenty of moisture. It is useful as a catch crop.
When growing kohlrabi, you will want to sow seed in the main plot in rows or blocks. The growing points should be about 250 mm (10 in) apart for summer and autumn crops, and about 300 mm (12 in) apart if the crop is to be left standing over winter; thin out as necessary. Sowing begins in late March and continues successionally about every four weeks until mid-July.
Pests and diseases: see Brassicas
Harvest when the swollen part of the stem is about 60 mm (2-1/2 in) in diameter; if allowed to grow longer the stems tend to become strong-flavoured and tough.
Recommended varieties: ‘Purple Vienna’, purple skinned, white flesh; ‘White Vienna’, pale-green skinned, white flesh
Soil: Rich; may need addition of hydrated lime
Sow: March to late summer
Harvest: When stems are about 60 mm (2-1/2 in) in diameter