When to Harvest Onions
Lifting a crop of homegrown onions is one of the high points of the summer veg patch, and getting the timing and drying right is what decides whether they keep until Christmas or into the following spring. Happily, onions make it obvious when they're done.
Quick answer
The signal is yellowing foliage that collapses by itself. Autumn-planted onions usually reach that point in early summer, with spring sets and seed-sown crops following between July and October. Get them out of the ground while some leaf is still attached, let them dry for a fortnight or so until the skins crackle, then keep them in a cool, airy spot that isn't dark.
Signs onions are ready to harvest
The foliage gives the clearest signal. As the bulbs mature, the leaves start to yellow, and the stems soften at the neck and topple over. Once most of the onions in a row have flopped, the crop is ready to lift.
There's no need to wait for every leaf to shrivel. Onions left in the ground too long can start to re-root or rot, especially in wet weather, and won't keep as well.
Should you bend the tops over? You may have heard that you should bend the tops over by hand to speed up ripening. Current advice is not to bother. Let the leaves fall naturally, as it's the most reliable sign that the bulbs are ready.
When are onions ready in the UK?
Overwintering (Japanese) sets planted in autumn: early summer, around June and July.
Spring-planted sets: ready from July to September.
Seed-grown onions: ready from late summer into October.
The exact timing varies with the weather, so let the leaves guide you rather than the calendar.
For planting advice, see when to plant onions in the UK
Harvesting onions carefully
Pick a dry, sunny day if you can. Work a fork into the soil just beside each bulb and lever it up gently. Lifting them from below avoids bruising, which is important, as bruised or damaged onions tend to rot in storage. Knock off loose earth by hand, and keep them away from the hose.
Keep any damaged onions to one side and use them first.
Drying onions after harvest
Proper drying is what makes onions keep for months. The aim is for the outer skins and the necks, where the leaves join the bulb, to become completely dry and papery.
In dry, sunny weather, spread the onions out in the sun, ideally raised on a wire rack or an old pallet so air reaches underneath. Leave them for about two weeks, turning them now and then. If rain is on the way, or the summer is damp, finish drying them under cover in a well-ventilated shed, porch or greenhouse. Wet weather at this stage can undo all your good work.
The neck test: you'll know they're done when the outer layers crackle and the necks have shrunk to thin, dry, tight stems. Any onion with a thick, soft neck won't keep well, so set it aside for cooking soon.
Storing onions
Store dried onions somewhere light, cool, dry and well ventilated. That surprises a lot of people, but a dark cupboard encourages them to sprout. Hang them in mesh bags, lay them out in slatted crates without touching, or plait the dry leaves together and hang them up.
Onions from overwintering sets keep until around early winter. Spring-planted and seed-grown onions store much longer, often until the following spring. Check them every few weeks and use any that soften.
Harvesting container onions
Onions grown in pots are harvested in the same way, but more easily. When the foliage has toppled, empty the pot onto some newspaper, sort out the onions and dry them in the same way.
For container advice, see growing onions in containers
Which onions to use first
A small part of your crop won't be suitable for storing. Use these first:
onions that bolted and produced a flower stalk
those with thick, soft necks
any bruised or damaged when lifted
bulbs with soft or discoloured patches
For full growing advice, see how to grow onions in the UK
For watering in the run-up to harvest, see how often to water onions
Common questions
When should I harvest onions?
Lift them once the foliage has yellowed and flopped by itself. That's early summer for autumn-planted onions, and from July onwards for those planted in spring.
Should I bend over onion tops before harvesting?
No. It used to be common advice, but it's no longer recommended. Let the leaves fall on their own, as that's the best sign the onions are ready.
How long should onions dry before storing?
Usually around two weeks in dry, sunny weather. The skins should be papery and the necks shrivelled and dry before they go into storage.
Where should I store onions?
Somewhere light, cool, dry and airy, in net bags, trays or plaits. Don't store them in the dark, as it encourages sprouting.
Harvest timings based on RHS guidance.