Growing Garlic and Onions: The Alliums That Almost Grow Themselves

If a nervous beginner asked for one crop guaranteed to reward them, the answer would not be tomatoes or salad — it would be the alliums. Garlic and onions are planted not from fiddly seed but from cloves and sets: ready-made planting units that skip the hardest weeks entirely. They are largely ignored by the pests that torment everything else, they occupy the ground quietly for months while asking almost nothing, and they end the season as one of the few crops you can store for half a year in a cool cupboard. The whole craft fits in three moves: plant at the right time, keep the weeds off, and stop watering on cue.

This guide covers the honest allium year — sets versus seed, the autumn-versus-spring timing that decides everything, the day-length quirk that trips up onion growers, the minimal care, and the harvest-and-cure ritual that turns a summer lifting into a winter’s worth of cooking.

Why Alliums Are the Beginner’s Crop

• You plant parts, not seeds: a garlic bulb breaks into a dozen cloves, each becoming a new bulb; onion sets are baby onions that simply resume growing. Both skip the germination gauntlet where beginners lose so many crops.
• Pests mostly stay away: the same pungency that flavors your cooking deters the grazers — slugs, most caterpillars, and browsing mammals give alliums a wide berth (which is why they double as companion plants among carrots and roses).
• They keep: unlike the eat-it-now urgency of salad or courgettes, well-cured garlic and onions store for months — a crop that feeds you long after the plot goes quiet.
• They are patient tenants: autumn garlic sits in the ground over winter needing nothing; the payoff is a long, low-effort occupation rather than a demanding sprint.

Choosing What to Plant

1. Garlic — buy seed garlic, not the supermarket bulb: supermarket garlic is often treated to resist sprouting and may carry disease or be a variety unsuited to your climate. Seed garlic from a supplier splits into two camps — hardneck (cold-hardy, fewer but bigger cloves, produces edible flower stalks called scapes) and softneck (milder climates, more cloves, stores longest and plaits well).
2. Onions — sets are the beginner default (the FAQ makes the full case), sold as small dry bulbs by variety and color; seed is the upgrade for variety and volume.
3. Match to day length (the onion quirk below) and to purpose: storage onions for the cupboard, sweet onions to eat fresh, red onions for color and salads.
4. Don’t forget the easy cousins: shallots grow exactly like onion sets (one bulb multiplies into a clump), and spring onions are the fast, forgiving gateway allium — sown thickly, pulled young, ready in weeks.

The Day-Length Quirk (Onions Only)

Onions bulb up in response to day length, and buying the wrong type for your latitude is the classic invisible failure. Long-day onions need the very long days of northern-summer high latitudes to trigger bulbing and fail (staying as thick-necked greens) further south; short-day onions bulb on shorter days and suit warmer, lower latitudes but bolt too early up north; day-neutral (intermediate) types hedge across a wide middle band. The practical move requires no astronomy: buy sets or seed from a supplier serving your region, or read the packet’s day-length note against your latitude. Garlic ignores all of this — it bulbs on cold and time, not day length.

Planting: The Whole Technique

• Garlic, in autumn: split the bulb into cloves at planting time (not before), keeping the papery skins on, and push each clove pointy-end up a few centimetres deep, spaced a hand-width apart. The cold it now receives is what splits it into a full bulb next year (the FAQ’s vernalization).
• Onion sets: push each set into loose soil so just the tip shows, a hand-width apart in rows — shallower than instinct suggests. Firm gently; birds love to tug freshly planted sets by their dry tops, so a net or a re-firming check in the first week saves a few.
• Soil sense: alliums want sun, free drainage, and soil that is fertile but not freshly manured (fresh nitrogen-rich muck grows leaves at the bulb’s expense and invites rot). A bed improved with compost the previous season is ideal — the soil guide’s standing advice.
• Containers work for garlic, shallots, and spring onions: a deep pot of free-draining compost on the balcony grows a respectable allium crop, on the container-watering rules.

The Care Year: Genuinely Minimal

1. Weeding is the one real job: alliums have sparse, upright leaves that cast little shade, so weeds steal their light and water unchallenged. Hand-weed gently and often (hoeing risks slicing shallow bulbs) — a weedy allium bed is the single biggest cause of small bulbs.
2. Water only while growing, and only in dry spells: steady moisture through spring builds the bulb; erratic drought-then-soak triggers bolting (the FAQ) and splits bulbs. Then comes the crucial reversal below.
3. Feed lightly if at all: a poor soil benefits from a spring feed as leaves grow, but stop by early summer — late nitrogen delays ripening and softens bulbs for storage. Never high-nitrogen; the tomato-style feast is exactly wrong here.
4. Scapes are a bonus harvest: hardneck garlic sends up curling flower stalks in early summer — snap them off (redirecting energy to the bulb) and cook them; they are a garden delicacy sold at a premium elsewhere.

The Most Important Instruction: Stop Watering

The single move that separates good allium growers from disappointed ones: as harvest approaches and the tops begin to yellow and flop, stop watering entirely. The plant is finished bulking and now needs to dry down; continued water at this stage rots necks, ruins storage, and undoes the whole season. Let the bed run dry, let the leaves collapse of their own accord, and resist the instinct to keep the hose going through the hot weeks. Dry-down is not neglect — it is the final, deliberate step of the crop.

Harvest: Reading the Signs

• Onions: when roughly half to two-thirds of the tops have naturally flopped and yellowed, they are ready — resist bending them over by hand (an old myth that can invite rot). Lift on a dry day, easing bulbs up with a fork, and leave them on the surface to start drying if weather permits.
• Garlic: harvest when the lower leaves have browned but several upper ones remain green — each green leaf is a protective wrapper around the bulb, so waiting until all leaves die gives loose, poorly-keeping bulbs. Lift carefully; garlic bruises and skins tear easily.
• Handle gently: bruised bulbs rot in storage. Brush off loose soil but don’t wash, and never yank by the stem — lift from below.
• The trial bulb: unsure? Lift one, cut across it, and check that the cloves or rings are plump and well-formed. Underground bulbs give little away until you look.

Curing and Storage

The FAQ carries the full curing method — two to four weeks of single-layer drying somewhere warm, dry, and airy until necks are papery and skins rustle — because curing is the difference between a crop that keeps for months and one that rots in weeks. After curing: trim roots, plait softneck garlic and onions into strings or cut stems to a few centimetres, and store cool, dark, dry, and airy — the open cupboard or a net bag in the shed, never a sealed container or the fridge. Eat thick-necked, bolted, or damaged bulbs first (they won’t keep), and check the stores occasionally, pulling any that soften. Done right, an autumn of planting feeds the kitchen deep into the following year.

The Allium Family: A Quick Field Guide

Rotation and Good Company

Two quiet habits raise allium success without extra work. Rotation: don’t grow alliums in the same bed year after year — onion white rot and other soil problems build up with repetition, so move the allium patch around a three-or-four-year cycle (the vegetable grower’s standard insurance, shared with the soil chapter’s logic). Companionship runs both ways: the pungency that keeps pests off alliums also protects their neighbors — the classic pairing sows onions or garlic among carrots, where each confuses the other’s specialist pest (onion fly and carrot fly hunt by smell), and alliums near roses are a traditional aphid deterrent. The one plant to keep them away from is beans and peas, which reputedly resent allium company. None of this is essential, but a rotated, well-companioned allium bed simply has fewer problems to troubleshoot below.

Alliums on the Balcony

Container growers are well served here. Garlic is one of the most rewarding pot crops going — a deep container of free-draining compost, cloves in for autumn, out the following summer, on the balcony guide's container-watering discipline (and the crucial dry-down before harvest, easy to control in a pot you can move under cover). Shallots and spring onions crop happily in shallower troughs, and a windowsill pot of spring onions resown every few weeks is the simplest indoor edible there is. The balcony's freedom from soil-borne white rot is a genuine bonus — pot alliums sidestep the very rotation worry that ground growers manage, needing only fresh compost each year.

Troubleshooting the Allium Bed

The Bottom Line

Alliums are the crop that makes a beginner feel like a farmer: plant garlic cloves in autumn and onion sets in spring, choose types that suit your latitude, then do almost nothing but weed diligently and water steadily through the growing months. When the tops flop and yellow, stop watering, lift gently, and cure for a few weeks until papery — and a single afternoon of planting turns into strings of garlic and nets of onions that flavor the kitchen for months. Few crops ask so little and give so long.