Onions, shallots and leeks prefer a light, deeply dug soil that has been manured the previous autumn or winter and with a dressing of a balanced fertiliser in early spring.
The easiest way to grow onions is from sets which are small immature onions that have been heat treated. They can be planted in early spring for harvesting in early summer. You can plant direct into moist soil or give them a start by placing them on a tray of moist soil or peat somewhere warm until the roots have grown about an inch.
Plant 5in (13cm) apart in rows 12in (30cm) apart so that the tip is showing. When the foliage starts to turn straw-coloured, ease the onions from the soil and allow to dry off until the skins are brittle. Hang the onions in nets or traditional strings in a cool, dry place, where they should remain in good condition for at least six months.
Onions can also be grown very successfully from seed sown under cover in trays as early in the year as possible or in shallow drills outdoors. Transplant the seedlings in spring at the same distances as for sets and use any thinnings as salad onions.
Japanese onion varieties are sown in late summer to overwinter and harvest the following spring or early summer. Sow in situ spacing the seeds about 1in (3cm) apart in shallow drills 9in (23cm) apart and thin out to 4in (10cm) apart the following spring. For spring onions see Spring or Bunching Onions.
Shallots, like small onions, are ideal for pickling, for flavouring and for grating or slicing in salads. Plant in late winter pushing the bulb into the soil to half its depth, allow 6in (15cm) between bulbs, 12in (30cm) between rows. Ensure the shallots are thoroughly dry before storing in nets or trays where they will keep in perfect condition for up to 12 months.
The gourmet vegetable that every gardener can grow. Sow under glass in winter or outdoors in early spring, very thinly about 0.5in (1.25cm) deep. When the seedlings are about as thick as pencils, transplant them to 6-8in (15-20cm) deep holes, made with a dibber, and spaced 6in (15cm) apart each way.
Simply drop the leek into the hole, then fill it with water. About three weeks after planting out give the leeks a dressing of a balanced organic fertiliser or Growmore, and a second dressing about three weeks after the first.
Leeks are hardy and should be dug as required for the kitchen.