When to Harvest Onions and Garlic (and How to Cure Them for Storage)

Timing is everything with onions and garlic. Lift them too early and the bulbs are small and won't keep; leave them too long and they can re-sprout, split, or start rotting in the ground. The good news is that both crops tell you very clearly when they're ready — you just need to know which signals to read. Here's how to judge the moment, lift the bulbs without bruising them, and cure them properly so they store for months rather than weeks.

The signs onions are ready

The classic signal is the tops falling over. As an onion bulb finishes swelling, the neck — the point where the leaves meet the bulb — softens, and the foliage flops over at that hinge and begins to yellow. Don't panic when the first plant keels over; wait until roughly two-thirds of the tops in the row have collapsed and started to dry naturally. At that point growth has finished, and the bulbs are as big as they're going to get. Flavour and storage quality peak when most of the foliage has died back, but don't leave lifted-ready onions in wet ground for more than a week or two: the risk of rot and re-sprouting climbs quickly, especially in a damp late summer.

Resist the old habit of bending the tops over by hand to 'hurry them up'. It doesn't speed ripening — the neck folds when the bulb is finished, not before — and the bruised, creased necks it creates are exactly where storage rot gets in later.

The signs garlic is ready

Garlic works differently: the tops don't flop. Instead, the leaves die back progressively from the bottom of the plant upwards, and each dying leaf corresponds to one of the papery wrapper layers around the bulb. The sweet spot for harvest is when the lower third to half of the leaves have yellowed and browned but the upper leaves are still green. Those remaining green leaves mean the bulb still has several intact wrappers, which is what protects the cloves in storage.

• Too early: the cloves are small, poorly defined, and the bulb hasn't divided fully — garlic lifted at this stage is usable but won't store.
• Just right: lower leaves brown, five or six upper leaves still green, cloves plump and well wrapped.
• Too late: nearly all the foliage has died, the wrappers split and stain, cloves start separating from the stem — use these bulbs first, as they keep poorly.
• Not sure? Sacrifice one bulb. Lifting a single test plant tells you more than any calendar date, because timing shifts with planting date, variety and weather.

How to lift them without ruining them

Choose a dry day if you can. Loosen the soil beside the row with a garden fork, insert it well below the bulbs, and lever them up gently rather than yanking on the foliage — a snapped neck or a fork wound turns a keeper into a use-this-week bulb. Brush off loose soil with your hands and leave the roots and tops attached for now. Whatever you do, don't wash the bulbs: added moisture is the enemy of everything that comes next.

Curing: the step that makes them keep

Curing is simply controlled drying, and it's the difference between onions and garlic that last until spring and ones that soften by October. Over two to four weeks, the necks dry and seal, the outer layers shrink into tight papery wrappers, and the skin colour deepens. Spread the bulbs in a single layer — on slatted trays, wire racks, or hung in small bunches — somewhere warm, dry and airy, out of direct sun and safe from rain and heavy dew. A covered porch, an airy shed, a greenhouse with shading and ventilation, or a spare room all work. You're aiming for good airflow around every bulb; a fan on low helps enormously in humid weather.

Storing your cured crop

The bulbs are cured when the necks are completely tight and papery with no give when squeezed, the outer skins rustle, and the roots have shrivelled to dry threads. Now trim: cut the tops back to about 2–3 cm (or plait them, if you've grown a softneck garlic or want a traditional onion string) and trim the roots close. Store only perfect bulbs — anything bruised, soft-necked, thick-necked or fork-damaged goes to the kitchen first. Keep the rest somewhere cool, dry, dark and ventilated: mesh bags, slatted crates and old baskets are ideal, sealed plastic bags and tubs are not. Well-cured storage onions and hardneck garlic will see you into late winter; softneck garlic often lasts longer still.

Tip: don't store onions and garlic next to your potatoes or apples. Potatoes release moisture that shortens onion storage life, and apples happily absorb onion and garlic flavours — nobody wants an allium-scented crumble.

Common mistakes to avoid

• Harvesting by the calendar instead of the plant — planting date, variety and weather shift the timing by weeks either way.
• Washing bulbs after lifting, which adds the moisture you're trying to remove.
• Curing in a heap — bulbs buried in the middle stay damp and rot first.
• Storing in the fridge long-term: it's too humid, and cool-then-warm cycles can trigger sprouting.
• Keeping every bulb — one soft onion in a full crate will quietly spread rot to its neighbours.

If something went wrong before harvest — rust-speckled garlic leaves, onions bolting into flower, or bulbs rotting at the base — a quick photo in PlantMe will help you name the problem, so next season's crop gets a cleaner run. The app recognises over 500 plant diseases and disorders and tells you whether it's something to treat or simply a quirk of the season.