Lift onions a week after the tops flop over, then dry them well

Onions are ready to lift when their leaves turn yellow and fall over at the neck, where the leaves meet the bulb. Wait about a week after most of the tops have gone over, then lift them on a dry day. In most UK gardens that’s June for onion sets planted the autumn before, and from late July to early September for sets planted in spring.

The flop is the onion telling you the bulb has stopped swelling. Leaving it in the ground for a few days more lets the skins firm up before you dry it.

When each type is ready

What you planted	When	Ready to lift	Keeps
Overwintering onion sets	Mid-September to mid-October	June to early July	A few weeks to two months
Spring onion sets	Early March to mid-April	Late July to early September	Several months
Onions from seed	Late January to early April	July to September	Several months
Shallot sets	October to November, or February to March	Mid-June to mid-August	Several months

Spring-planted sets take roughly 90 to 120 days from planting to harvest. Onions from seed take longer, around 120 to 160 days from sowing. In Scotland and the north the whole harvest runs a couple of weeks later, and a wet summer can hold the tops upright longer than usual.

Lifting

1. Pick a dry spell. Onions lifted wet are harder to dry and more likely to rot.
2. Push a fork into the soil a little way from the row and lift gently, so the bulbs come up with their roots intact. Don’t pull them by the leaves.
3. Shake off loose soil. Don’t wash them.
4. Handle them like apples. A bruised onion rots in store.

Shallots come up as a cluster of bulbs. Leave the clusters whole while they dry and split them afterwards.

Drying, the step that decides how long they keep

Spread the onions out in a single layer somewhere sunny and airy for two to three weeks. A wire rack, an old pallet or a greenhouse bench lets the air get underneath. On a dry, sunny spell they can sit on the bed, but bring them under cover if rain is forecast.

They’re ready to store when:

• the outer skins are papery and rustle when you handle them,
• the necks are thin and completely dry,
• the roots are brittle.

Trim the roots and cut the leaves back to a few centimetres, or leave the leaves on and plait them. Store in nets, open trays or plaits somewhere cool, dry and airy. A cold shed or garage is ideal. A warm kitchen makes them sprout.

When onions aren’t ready, or go wrong

Tops still upright in September. Usually a sign of too much nitrogen, or a cool, wet summer. Lift them anyway before autumn rain sets in, and use them first.

A flower stalk in the middle. The onion has bolted. Snap the stalk off, lift it when you need it and eat it soon, as the hard core won’t store.

White, fluffy mould at the base. Onion white rot. Lift and bin affected plants, not the compost heap, and don’t grow onions, garlic, leeks or shallots in that bed for many years. Our crop rotation planner helps you keep them moving round the plot.

After the onions come out

An onion bed cleared in July still has months of growing in it. Quick crops such as lettuce and beetroot fill it well, and both grow happily beside any onions still waiting to come out. Check what’s due in the sowing calendar.

For planting times and spacing, see when to plant onion sets.