Onions are fairly easy to look after and once harvested will store for weeks.
Onions don’t need much on-going care, but you should weed the soil around them regularly when they are young. Once they are almost full size, the presence of weeds will help the bulbs ripen by keeping the soil dry. Equally, young plants need to be kept moist but not wet - and you should stop watering them a good week before harvesting them or the ripening process will be delayed.
Main crop and Japanese onions will be ready to be harvested a week or two after the foliage starts to turn brown and die off. As a general rule, onions sown in spring should be ready for harvesting in August. Those sown in late summer or autumn, will be ready from June.
Try to harvest your onions on a warm, sunny day, then gently lift them from the soil with a fork and leave them to dry in the sun. Don’t let them get wet – the more they dry, the better they’ll keep. After a few days, remove any remaining foliage and move them to a dry, dark place to store them (garage, shed, kitchen cupboard...).
Spring onions are harvested when they're around 45cm tall. Unlike other onions, which can be kept for up to eight weeks in a cool, dry place, spring onions should be eaten within a couple of days.
For more on harvesting vegetables, check out our guide.
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