Sow seeds thinly from April to August 13mm (½in) deep in rows 25-45cm (10-18in) apart.
Some types can be sown all year round in a warm greenhouse, conservatory or on a windowsill.
After sowing, keep well watered until seedlings appear.
When large enough to handle thin seedlings to between 10-30cm (4-12in) apart.
Sowings made in late summer will carry on cropping into winter if protected with cloches or similar.
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.
More info on Flea beetle
Slugs and snails: These feed on the young seedlings and you'll see the tell tale slime trail on the soil around your crop, as well as on the leaves.
Remedy: There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers, copper tape and biocontrols.
More info on Slugs and snails
Harvest young leaves as required, picking a few only from each plant.
Nigel Slater offers up this garlic, ginger and spring onion that come together in this Thai-style brassica stir-fry.