how to grow your own onions

Whether you prefer white or red onions, the planting process is basically the same. Photography: Julian Winslow/ableimages

Can onions be beautiful? I believe they can. I have fond memories of some Red Baron I pulled from the earth four or five years ago, when they had barely begun to swell. Almost white at the roots, shading to purple, then green, they glowed. I occasionally show the photo to friends. Perhaps one day you’ll know such happiness.

You’ll need some sunny, well-drained ground – as much of it as possible, since so many dishes call for onions and they store well. (It’s entirely possible to grow onions in containers, particularly densely packed spring onions, but it’s not the best use of limited space.) Ideally you’ll have dug in plenty of manure a few months before, but if not you can freshen it up with a generous helping of compost. You may also have to adjust the pH with lime, as onions hate acid soil (visit the Royal Horticultural Society for advice.

You can grow onions from seed, but for an easy life opt for “sets” – tiny bulbs which a professional has gone to the trouble of cultivating. Garden centres are fond of boring yellow types, but I’d aim for a mixture of red and white. Planted between the middle of March and the middle of April, they should be mature come August or September.

To plant your sets, scratch out drills (furrows) about 30cm apart, just deep enough to take the little bulbs. Carefully place these, roots down, fill the drill, gently firm the soil so the tips of the bulbs are just about poking through the surface, and water well. The usual advice is plant the sets 10-15cm apart, but I’d plant twice as densely and thin them as they grow, so you can eat spring onions while the other half of the crop matures. Water the growing plants lightly but often during dry spells, trying not to wet the greenery. For the first few months you can give the occasional feed of liquid fertiliser. Once the bulbs have swollen, stop feeding and watering.

Onions can be harvested at any size, but if you want to store them, wait until the foliage has turned yellow and flopped over. Lift the bulbs with a fork and allow them to dry thoroughly, ideally on a rack or grill which lets the air circulate.

Growing shallots is very similar, except that you plant full-size bulbs 15-20cm apart, and leave them without thinning until their foliage dies down. By then each bulb will have turned into a cluster of six or more.

Phil Daoust is a food writer based in England and France. Twitter: @philxdaoust