There is a particular satisfaction in eating your own onions in February, or cutting into a squash you grew yourself while the rain hammers the greenhouse. But storing homegrown vegetables is not simply a matter of piling them in a shed and hoping for the best. A few simple preparations in autumn will carry you through to spring, while a bit of neglect can turn a beautiful harvest into a mouldy, sagging mess by Christmas. The good news is that the rules are straightforward, and once you have a system in place, it becomes as much a part of the gardening year as sowing and weeding.

Cool, dark, dry and airy: the four conditions that matter

Before you so much as lift a single onion, think about where your produce is going to live. Most British garden crops store best somewhere between 4°C and 10°C, in darkness, with decent air movement and protection from frost and damp. A garage, an unheated spare room, a well-ventilated loft or a proper root store all work well. A garden shed can be fine too, provided it does not swing wildly between baking hot on a sunny October day and freezing in January.

Airflow is the detail people overlook most often. Vegetables breathe, and the moisture they give off needs somewhere to go. Slatted shelves, open crates, nets and loosely folded paper sacks all allow air to move. Sealed plastic boxes do the opposite, trapping damp against the skins and inviting rot. Try to avoid stacking produce against a cold external wall, where condensation gathers, and keep your store away from ripening fruit. Apples and pears release ethylene gas, which speeds up sprouting in potatoes and softening in everything else, so give them their own space.

Curing onions, shallots and garlic

Onions that go into store straight after lifting will almost always rot. They need curing first, a process that dries the outer skins and seals the neck where the leaves were. Lift them on a dry day and leave them on the soil surface for a few hours if the weather is kind, then move them somewhere under cover that is warm, dry and airy — a greenhouse bench, a porch or a shed shelf with the door open.

Spread them out so they are not touching and leave them for two to three weeks. They are ready when the skins rustle like paper, the necks are completely dry and pinched-looking, and there is no green left anywhere. Then you can:

• Plaît them into ropes using soft string or raffia
• Drop them into old netting, onion bags or the legs of clean, worn-out tights, hung from a hook
• Lay them in single layers in shallow crates or cardboard trays

Check them as you go and set aside any with thick, soft necks or bruising — those are the ones to use first. Shallots and garlic follow much the same routine, though garlic is happiest at the cooler end of the range and plaits particularly well.

Squash and pumpkins: cure with warmth, store in the cool

Winter squash are often stored badly because they need the opposite treatment to most crops. They must be cured somewhere genuinely warm — around 20°C to 25°C — for ten days to a fortnight, which hardens the skin and heals small grazes. A sunny windowsill, a warm greenhouse bench or the airing cupboard shelf all do the job nicely.

Leave the fruit on the plant until the skin is hard enough to resist a fingernail and the stalk has gone corky, then cut with a good long handle, five to eight centimetres of it. Never carry a squash by its stalk; that is the first place rot gets in. Once cured, move them to somewhere around 10°C to 13°C. Below 10°C they suffer chilling damage, which shows up later as dark sunken patches and a rapid collapse.

Store squash in a single layer on slatted shelves, stalk uppermost, not touching each other. Thick-skinned varieties such as 'Crown Prince' and 'Uchiki Kuri' will usually outlast thinner-skinned butternuts, so eat the butternuts first.

Potatoes, roots and the rest of the winter larder

Potatoes should never be washed before storage. Let them dry, brush off loose soil and reject any with cuts, blight spots or slug damage — one rotting tuber can taint a whole sack. Hessian sacks, paper sacks or cardboard boxes in the dark at around 4°C to 7°C will keep them firm and sprout-free well into spring.

For carrots, beetroot, parsnips, turnips and celeriac, a box of slightly damp sand, spent compost or coir in a cool, frost-free place is hard to beat. Lay the roots so they are not touching and cover each layer. Alternatively, parsnips and winter carrots can simply be left in the ground under a thick mulch of straw or bracken and lifted as needed, though you will need to beat the slugs to them. Check stored roots every couple of weeks for any sign of root fly damage or soft brown patches.

The weekly walk-round that saves the harvest

However carefully you set things up, some produce will always begin to turn. The single most useful habit you can develop is a ten-minute inspection every week or so, working through each crate and net by hand. Remove anything soft, mouldy or suspicious straight away, and wipe away any damp patches in the box itself. Rot spreads quickly through contact, so one bad onion left in a net can ruin a dozen of its neighbours.

Do not despair over doubtful specimens. A softening squash can be roasted, puréed and frozen; bruised apples become chutney; sprouting potatoes are fine for an early crop of salad leaves. Note down in your journal what keeps well and what does not, along with the date you lifted each crop and the weather that autumn. After two or three years you will know precisely which varieties and which corner of the shed suit you best — and there is no better feeling than a February kitchen filled with the smell of your own stored onions softening in the pan.