Red onions are the showpiece of the onion patch: deep purple-red skins, crisp white flesh with red rings, and a mild, sweet flavour that is at its best raw in salads and sandwiches. They are also the onion most often picked at the wrong time, because the signs of readiness are easy to miss if you have only grown yellow storage onions before. Red onions are usually grown for fresh eating rather than for months of storage, and harvesting them at the right moment — and curing them properly — is what gives you a firm, sweet bulb instead of a soft one that rots in the bag.
Red onions take 90–120 days to mature, according to the Garden Grove crop data. They are a hardy vegetable in the Amaryllidaceae family with moderate water needs, so they tolerate cool weather and grow through a long season. The tops tell you when they are ready, and the tops are honest: when they fall, the bulb is done growing. For the full growing picture, see our growing guide for red onions, and use the Harvest Date Calculator to work out your lifting window from your sowing date.
Red onions at a glance
| Growing factor | What red onions need |
|---|---|
| Days to maturity | 90–120 |
| Category | vegetable |
| Family | Amaryllidaceae |
| Cold tolerance | hardy |
| Water needs | moderate |
Signs a red onion is ready to pick
The tops are the first and most reliable sign. When red onions are ready, the green tops yellow, soften and fall over — usually most of the tops in a row will flop within a few days of each other. This is the plant telling you it has finished: the bulb has stopped growing and the neck has started to seal. Do not wait for every top to be completely brown and dry; when roughly half to most of the tops have fallen, the crop is ready to lift.
The bulb is the second sign. Brush the soil away from the top of a bulb and look: a ready red onion is well rounded, firm, and has developed its deep red-purple papery skin. The neck — where the leaves meet the bulb — should feel soft and papery rather than thick and green. A thick, green neck means the bulb is still growing and will not store well, because moisture can get in through the neck.
Size is the third check, and it varies by variety: some red onions are naturally smaller than yellow storage types. Compare bulbs in your own row — when the largest have stopped swelling and the tops are falling, they are ready. Pull one as a test bulb: it should be firm all over, with tight, dry outer skins and no soft spots. For the other storage onions, see our guide to when to harvest yellow onions and when to harvest white onions.
How to lift red onions without damaging them
Lift onions, do not pull them. Loosen the soil around each bulb with a fork first, working a little way out from the bulb so you do not spear it, then lift the bulb gently by its base. Pulling an onion straight out of firm soil tears the roots and can bruise the bulb, and a bruised onion rots first in storage.
Handle the bulbs gently throughout. Do not throw them into a bucket, do not knock them against each other, and do not cut the tops off immediately — the tops are part of the curing process. Lay the lifted bulbs in a single layer on the soil or on a rack, tops and all, and let them dry in the sun for a day or two if the weather is dry. If rain is forecast, move them under cover straight away.
The best time of day to harvest
Lift onions on a dry, sunny morning, after the dew has dried. Dry bulbs cure far better than wet ones, and a sunny day gives the curing process a good start. The soil should be dry enough to crumble away from the bulbs rather than sticking to them in wet clods.
Avoid lifting onions in wet weather or from sodden soil if you can. Wet bulbs take much longer to cure, and moisture trapped in the neck is the main cause of rot in storage. If you have no choice and the tops have fallen during a wet spell, lift them anyway — leaving them in wet soil is worse — and get them under cover to dry as quickly as possible.
How often to pick
Onions are a single-harvest crop: the whole row comes ready at roughly the same time, and you lift it in one or two passes. Once the tops have fallen, do not leave the bulbs in the ground for more than a few days — they can start to regrow in wet weather, and the skins can split. Lift the row, cure the crop, and the harvest is done.
You can, however, pick red onions earlier for a different use. Young red onions pulled while the tops are still green make excellent spring onions or salad onions — mild, crisp and sweet. If you sowed thickly, thin the row by pulling the smallest plants as spring onions, and leave the rest to bulb up. Because red onions are hardy, the season is long and forgiving, but the final lift should happen before prolonged wet autumn weather sets in. See Zone 6 red onions for an example of seasonal timing, and check your local extension service for lifting dates in your area.
What happens if red onions are left too long
A red onion left in the ground after its tops have fallen will not get bigger — it will get worse. In wet weather the bulb can start to regrow, sending out new green shoots from the top, and the skins can split and let in rot. In dry weather the bulb simply sits there and dries out, losing weight and flavour.
A bulb left too long is also more likely to be damaged by onion fly and other pests, and to rot from the base. If you find a bulb has started to regrow or has gone soft, use it straight away rather than storing it — it will not keep. The rule for onions is simple: when the tops fall, lift.
How to store red onions
Short term, fresh red onions keep well in a cool, dry, well-ventilated place. After curing (see below), trim the roots and cut the tops to a few inches above the bulb, or braid the tops together if they are long enough. Store the bulbs in a mesh bag, a basket or a crate, in a single layer if you can, somewhere cool and dark with good airflow.
Curing is the step that makes storage work, and it matters for red onions even though they are not the longest-keeping type. Spread the lifted bulbs in a single layer in a warm, dry, airy place — a shed, a garage or a covered porch — for two to three weeks, until the outer skins are papery and rustle when you touch them and the neck is completely dry and tight. Turn the bulbs occasionally so they dry evenly. Only store bulbs that are firm and sound; any soft or damaged bulb should be used first.
Red onions do not store as long as yellow onions — their skins are thinner and their flesh is milder, so they are best used within a few weeks to a couple of months, and they are at their best fresh. Keep them away from potatoes, which release moisture and gases that make onions sprout, and never store onions in a sealed plastic bag or in the fridge, where damp and cold encourage rot and sprouting.
If you grow a lot of onions and want to plan quantities, the Vegetable Yield Estimator can help you work out how many to plant next season.
Succession and continuous harvest tips
Onions are not succession-sown for bulb harvest — one sowing gives one crop. The way to get a longer supply is to grow different types: red onions for fresh eating, yellow onions for long storage, and a row of spring onions for early picking. You can also sow a second, later batch of red onions for young salad onions if your season is long enough.
Keep the bed weed-free while the bulbs are swelling, because onions compete badly with weeds, and water steadily until the tops start to fall — then stop watering entirely, because dry soil helps the bulbs cure in the ground. Do not feed onions late in the season, or the tops will stay green and the bulbs will not ripen. Browse the full guides hub for more harvest timing advice, and check your local extension service for varieties that store well in your climate.
Frequently asked questions
When are red onions ready to harvest?
When the tops yellow and fall over, the bulb is well rounded with deep red-purple papery skins, and the neck feels soft and papery. Maturity is typically 90–120 days.
How do I cure red onions?
Spread the lifted bulbs in a single layer in a warm, dry, airy place for two to three weeks, until the skins are papery and the neck is completely dry. Turn them occasionally and only store firm, sound bulbs.
How long do red onions last in storage?
Red onions are best used within a few weeks to a couple of months — they do not keep as long as yellow storage onions. Store them cool, dry and ventilated, away from potatoes.
Can I eat red onions straight after lifting?
Yes, but they taste better after a short cure, which dries the skins and concentrates the flavour. Young onions pulled early are excellent as spring onions.
Why did my red onions go soft in storage?
They were probably stored before curing fully, stored damp, or bruised at lifting. Cure until the neck is dry and tight, handle gently, and check your local extension service for storage advice suited to your area.