How to Cure and Store Onions and Garlic for Winter

By late August, the onion bed looks as though it has given up. Tops flop over, the leaf tips brown, and bulbs sit half out of the soil waiting to be lifted. What happens in the next three weeks decides whether you are still pulling firm, sweet onions out of a crate in February or binning a slimy crop by Bonfire Night. Curing is not a chore to rush. It is the difference between a store crop and a compost heap.

Why curing matters more than storage

A freshly lifted onion or garlic bulb is still a living thing, full of moisture and still respiring. The neck — where the leaves meet the bulb — is the weak point. If it stays thick and damp, rot gets in, and once it does, one bad bulb can take a whole crate with it.

Curing dries that neck down to paper, tightens the outer skins and seals the bulb. You will know it has worked when the tops rustle, the roots snap like straw and the neck feels thin and dry rather than rubbery. A properly cured bulb keeps for months. A rushed one is soft before Christmas.

Lifting at the right moment

Stop watering onions and garlic two to three weeks before you plan to lift them. Dry soil at harvest means drier bulbs.

Onions are ready when the tops have fallen over, the tips have yellowed and the necks have begun to soften. Lift them with a fork rather than pulling, and don't bend the tops over to hurry things along — it does nothing useful and lets water into the neck.

Garlic works the other way round. Lift it while a few leaves are still green, usually when about half the foliage has yellowed. Leave hardneck garlic much longer and the bulbs split and lose their papery wrapper. Shake off the worst of the soil, but do not wash them; the rest will brush off once dry.

Drying: the curing process

You need four things: warmth, low humidity, shade and moving air. A dry shed, a greenhouse with the door open, a garage or a covered porch all work well. Aim for roughly 20–25°C and keep the bulbs out of direct sun, which can scorch the skins.

1. Lay onions and garlic in a single layer on mesh racks, slatted trays or newspaper, so the bulbs barely touch.
2. Leave tops and roots intact while they dry. The tops draw moisture out of the bulb as they wither.
3. Turn them every few days and check underneath for any that are going soft.
4. Give it two to three weeks. In a wet, cool summer it takes longer, and a fan or dehumidifier is worth the electricity.
5. Cure under cover if the forecast is unsettled. Rain on a nearly cured crop undoes a fortnight of work.

Short of space? Hang garlic in bunches of eight to ten bulbs from a rafter, or thread onions onto string. Air moves around them better than it ever will in a box.

Trimming and sorting

When the necks are completely dry — no green, no rubberiness — it is time to tidy up.

• Cut tops to about 2–3cm above the bulb if you are storing in nets or boxes, or leave them long if you plan to plait.
• Trim roots back to roughly 1cm.
• Rub off flaking skin and loose soil with your hands. Don't peel back the tight, dry layers; they are the bulb's protection.
• Set aside anything with a thick neck, a soft patch, a split wrapper or a bruise. Those go to the kitchen first.
• Keep varieties separate, so you know what you are eating in March.

Getting storage conditions right

Temperature

Onions and garlic store best either cold or properly cool: around 0–4°C, or 10–15°C. The awkward zone is 5–10°C, which wakes bulbs up and sets them sprouting. A frost-free garage, a cool cupboard or a spare-room floor out of the sun all work.

Humidity and air

Keep the air dry and moving. Around 60–70% relative humidity suits onions; garlic prefers it drier still. Never seal bulbs in plastic — they sweat, and sweating leads to mould. Keep them away from potatoes and ripe fruit, which give off ethylene and encourage sprouting.

Containers

Plaits, nets, old tights, slatted crates, cloth bags and cardboard trays all do the job, because air reaches the bulbs. A deep pile is a mistake: two or three layers at most, with the biggest bulbs at the bottom. Label each container with the variety and the date.

Checking for trouble

Look through your store every few weeks. A bulb with a brown, sunken patch at the neck has neck rot; take it out, bin it rather than composting it, and check its neighbours. Sprouting bulbs are not dangerous — use them straight away, though the cloves will be softer and more bitter. A store that smells sharp or musty needs sorting out, and the room needs more air.

Save the best, eat the rest

Before the crate is closed, pick out a dozen of the healthiest, truest bulbs of each variety and keep them separately for planting next autumn. Keep a small basket in the kitchen for anything damaged or thick-necked, and use those first. Cure the crop properly now, spend ten minutes checking once a month, and the onions in your winter stew will still be firm, sweet and worth the wait.

Photo: pooliwattano P / Pexels