This odd brassica looks like a sputnik but don’t let this put you off. It has a delicious smell and nutty flavour. More drought resistant than most brassicas, it succeeds where swedes and turnips fail. Green varieties are sown from mid spring to mid-summer for summer crops; hardier purple varieties are sown from mid-summer for autumn and winter crops.
Create a firm seed bed in any reasonably light, fertile, free draining soil. Sow seeds, 1cm (½in) deep in rows 30cm (12in) apart from late February (under cloches or fleece) to early March, continuing until mid-August in warmer areas.
Sow a little and often, say every three weeks, for a constant supply.
In cooler areas and where soil is heavy clay, early crops can be sown in modules, hardened off and transplanted when the soil warms up, when they are a maximum of 5cm (2in) high.
Thin out seedlings when they are 2.5cm (1in) tall or the first true leaves appear, leaving a final spacing of 15cm (6in) apart.
Keep the soil constantly moist and weed free, watering before the onset of drought.
Net or fleece young plants, to protect against birds and cabbage root fly.
Cabbage root fly: White larvae approximately 5cm (2in) long, feed on the roots just below the soil surface, stunting growth and causing plants to wilt and die.
Remedy: Grow under insect-proof mesh or horticultural fleece. Seedlings are most vulnerable.
Flea beetle: Leaves are covered in small holes and damaged areas turn brown. Seedlings are particularly susceptible.
Remedy: Grow plants under horticultural fleece and keep the soil moist. Water in nitrogen-rich fertilser to help the crop outgrow the pest.
Club root: Roots become swollen and distorted, and leaves become pale and yellow and wilt easily. Plants may die.
Remedy: Improve drainage and add lime to make soil more alkaline. Do not grow in affected soil.
It’s important to harvest when the plants are young and the swollen stem bases are between golf- and tennis ball-size. If you leave them too long they lose their taste and tenderness.
Plants can be harvested until mid-December, and the leaves can also be eaten.