Why the First Fortnight Decides Everything

You can grow a beautiful crop of onions and garlic, lift them at exactly the right moment, and still lose the lot by Christmas — not through slugs or white rot, but through rushing the drying. The single most common mistake on British allotments is bringing bulbs indoors too soon, or stacking them in a warm shed where they sweat, soften and rot from the neck down. Get the curing right and the rest is easy. Get it wrong and no amount of clever storage will rescue them.

The principle is simple: a bulb you want to keep through winter is a living thing in a dormant phase. Its outer skins need to be dry, papery and tight, and the neck — where the leaves joined the bulb — needs to be shrivelled and closed. Until that happens, the bulb is still losing moisture through soft tissue, and any small wound is an open door for botrytis and neck rot.

Lifting at the Right Moment

Onions are ready when the tops begin to topple and the necks feel soft rather than stiff. Don't bend the tops over to force it; that old trick bruises the neck and invites rot in. Wait for nature to do it. If the weather turns wet and the bulbs are already fat, lift anyway and dry them under cover.

Garlic is different. Lift it while three or four wrapper leaves are still green — usually late June to mid-July for hardnecks, a little later for softnecks. If you wait until the foliage is fully brown, the bulbs will have split their skins and they'll store badly. Ease them out with a fork rather than pulling, and never wash them.

• Lift on a dry morning if you can, so the soil brushes off easily.
• Leave roots and tops intact for now — they help the bulb dry evenly.
• Handle bulbs as if they were eggs; every bruise is a future rot.
• Keep hardneck garlic and softneck garlic separate, as they store very differently.

Curing: Two to Three Weeks of Patience

This is the stage most people skip. Lay onions and garlic out in single layers on racks, mesh trays or old bread crates, somewhere warm, bright and genuinely airy. A greenhouse, polytunnel or covered lean-to is ideal. In a good summer you can do the first few days outside in full sun, then move them under cover so dew and rain don't undo the work.

Leave them for two to three weeks. You're looking for dry, rustling skins, a papery neck that pinches shut with no give, and roots that snap off cleanly. Garlic stems should be dry enough to twist off easily. Only then should you trim the roots and tidy the tops, and even then leave a stub of an inch or so rather than cutting flush against the bulb.

If the weather is damp or the space is humid, give them longer. There is no prize for speed. A bulb that still feels cool and firm at the neck needs another week on the rack.

Plaiting, Bundling and Hanging

Softneck garlic and onions with dry, flexible tops are perfect for plaiting. Start with three bulbs, cross the leaves over each other and weave in a new bulb as you go, keeping the plait tight. Finish with a loop of string and hang it somewhere cool and dark. Alternatively, tie the dry tops into bundles of eight or ten and hang those — quicker, and just as effective.

Hardneck garlic has stiff, brittle stems that won't plait. Cut the stems an inch above the bulb and store the bulbs loose in netting, or lay them in a single layer in shallow boxes. Whatever method you choose, the rules are the same:

• Air must be able to move around every bulb — never pile them deep.
• Keep them off concrete floors, which draw damp and chill.
• Hang plaits and bundles clear of walls so air circulates behind them.
• Label by variety if you're saving your own seed stock, so you know what performed best.

The Right Conditions for Winter Storage

Onions want cool, dark and dry: roughly 0–5°C with low humidity, in a frost-free shed, garage or spare room. Garlic is similar, though it holds slightly better a touch colder and will keep for months in a cool, airy place. What both hate is the warm, humid fug of a modern kitchen — a bowl by the cooker will have bulbs sprouting green shoots by January.

Frost won't usually kill the bulbs, but freezing and thawing ruins the texture, so keep them frost-free. Avoid sealed plastic bags and airtight tubs entirely; a cotton sack, string bag, or open crate is far better because it breathes. Old clean tights make excellent hanging storage for garlic.

Checking, Using and Troubleshooting

Look through your store once a month. Any bulb that feels soft, shows grey fuzz at the neck, or has gone light and hollow should come out immediately — rot spreads to its neighbours through contact. Eat the doubtful ones first if they're still sound inside.

Bear in mind that not every bulb is a keeper. Thick-necked onions, ones that bolted to flower, and any with damaged skins should be used fresh in autumn. Hardneck garlic generally stores until Christmas or the New Year; softneck garlic and good keeping onions such as Sturon or Red Baron will carry you well into spring. Green sprouts in midwinter simply mean somewhere in the store is too warm — move the rest somewhere cooler and use the sprouting ones first, because they're still perfectly good in the pan.