Onions are easy and cheap to grow, both from seed and from heat-treated sets. Follow our step-by-step guide, below, to growing onions from seed (skip to Step 3 for instructions on planting out sets).
Onion sets are miniature or immature onions, which can be planted out in March or April for a quick-growing crop. Sets are available from garden centres or by mail order, and although the range of varieties is not quite as wide as from seed, it’s is an easy, reliable method of growing.
Whether you grow from seeds or sets, you can start to harvest bulbs in early summer and have plenty to store through winter.
As with the majority of vegetables, onions grow best in a well-lit position, with soil that has been enriched with generous amounts of plenty of organic matter.
Once dried, a convenient way to store onions is to string them up in onions ropes and hang them in a cool, dry, frost-free place. Select only unblemished bulbs with narrow, well-closed necks. Wide-necked onions do not store well so use them first