How to grow Onion (Bulb)
in the UK

Onions are a cracking staple, aren't they? You can use them in so many dishes, and a good harvest really does set you up for the year. They're not too tricky to grow on the plot, a medium difficulty crop I'd say, and well worth the effort.

Sowing

Right, for onions, you've got a couple of options. You can start them from seed indoors in February or March, that's what I often do. Sow them thinly, about 1 cm deep, in trays or modules, and keep them somewhere warm, like on a windowsill or in a heated propagator. Once they've sprouted, give them plenty of light. Alternatively, you can plant onion sets directly outdoors from March to April. Sets are little immature onions, and they're proper easy to get going, just push them into the soil so the tip is showing. Whichever way you go, make sure the soil's not too cold.

Growing on

If you've started seeds indoors, you'll need to prick them out into individual modules or small pots when they're big enough to handle, usually after a few weeks. Before planting out in late April or May, once the risk of a hard frost has passed, harden them off for a week or two. That's just gradually getting them used to the outdoors, you know. Plant them out about 10 cm apart in rows, leaving 20-30 cm between rows. You can get plug plants too, which saves a job, just pop them straight in.

Looking after it

Onions like a consistent supply of water, especially during dry spells, but don't let them get waterlogged. Keep the plot weed-free, as weeds will compete for nutrients and water. A general-purpose feed can help them along, but they don't need a huge amount of fuss. Just keep an eye on them through the season.

What goes wrong

Onion fly can be a bother, laying eggs at the base of the plants, but growing them near carrots can help confuse the little blighters, like I say, companion planting works. White rot is a fungal disease that can be tricky, so it's best to rotate your crops and avoid planting onions in the same spot year after year. Slugs generally leave them alone, which is a bonus.

Harvest

You'll know your onions are ready for harvest when their leafy tops start to yellow and fall over, usually from July through to September, about 150 days after sowing. Gently lift them out of the ground with a fork. Then, and this bit's important, dry them thoroughly for a couple of weeks, ideally somewhere sunny or under cover. Once they're papery and dry, store them in a cool, dark, airy place.