Gradually thin seedlings to 7.5-10cm (3-4in) for baby leaf, to 20cm (8in) for semi-mature plants and to 25-30cm (10-12in) for mature plants. The thinnings can be eaten.
Keep plants well watered throughout the growing period to avoid bolting (running to seed) and lack of flavour.
Flea beetle: Leaves are peppered with small holes, damaged areas turn brown. Seedlings are particularly susceptible.
Remedy: Grow under horticultural fleece, keep the soil moist.
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Powdery mildew: A white powdery deposit appears over the leaf surface, leaves become stunted and shrivel.
Remedy: Keep the soil moist, grow in cool locations, spray using plant and fish oils or sulphur based controls.
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Bolting: Plants flower and set seed, rather than producing edible roots. This is usually caused by stress usually drought.
Remedy: Sow bolting resistant varieties, warm the soil before sowing early crops, grow under the protection of fleece or cloches and keep the soil moist.
Harvest as and when needed.
'Joi Choi': Is slow to bolt and has good frost resistance.
'Canton Dwarf': Is compact with dark green leaves.