Yellow onions are the workhorse of the vegetable garden: the onion that stores for months, the onion that goes into almost every cooked dish, and the onion that repays careful harvesting more than any other. A yellow onion lifted at the right moment and cured properly will keep firm and sweet in a cool cupboard for months. The same onion lifted too early, bruised at harvest, or stored before its neck is dry will rot within weeks. The difference is entirely in the harvest and the cure.
Yellow 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. Their thick, golden-brown skins are what make them the best storage onion of all — but those skins only protect the bulb if they are fully dried and the neck is sealed. For the full growing picture, see our growing guide for yellow onions, and use the Harvest Date Calculator to work out your lifting window from your sowing date.
Yellow onions at a glance
| Growing factor | What yellow onions need |
|---|---|
| Days to maturity | 90–120 |
| Category | vegetable |
| Family | Amaryllidaceae |
| Cold tolerance | hardy |
| Water needs | moderate |
Signs a yellow onion is ready to pick
The tops are the first and most reliable sign. When yellow onions are ready, the green tops yellow, soften and fall over — most of the tops in a row will flop within a few days of each other. This is the plant finishing its work: the bulb has stopped growing and the neck is starting to seal itself. When roughly half to most of the tops have fallen, the crop is ready to lift. Do not wait for every top to be brown and dry.
The bulb is the second sign. Brush the soil away from the top of a bulb and look: a ready yellow onion is well rounded and firm, with golden-brown papery skins that feel dry and rustle when touched. 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 enters through the neck and rot follows.
Size is the third check. Yellow onions are usually the largest of the bulb onions, and a mature bulb should feel heavy and dense. Compare bulbs in your own row, and pull one as a test: it should be firm all over, with tight, dry outer skins and no soft spots. A bulb that feels light or hollow is not ready or has dried out. For the fresh-eating onions, see our guide to when to harvest red onions and when to harvest white onions.
How to lift yellow 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 bruises the bulb, and a bruised onion rots first in storage — even a thick-skinned yellow one.
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 and the neck needs to dry naturally. 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 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 also pick yellow onions earlier for a different use. Young yellow onions pulled while the tops are still green make good spring onions, and thinning a thick sowing this way gives the remaining bulbs more room to grow. Because yellow 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 yellow onions for an example of seasonal timing, and check your local extension service for lifting dates in your area.
What happens if yellow onions are left too long
A yellow 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 dries out and loses weight.
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 yellow onions
Curing is the step that makes months of storage possible, so give it the time it needs. 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. The neck is the test: if it still feels soft or damp, the onion is not ready to store.
Once cured, trim the roots and cut the tops to a few inches above the bulb, or braid the tops together if they are long enough — braided strings of onions look wonderful hanging in a kitchen and they keep well. Store the bulbs in a mesh bag, a basket or a crate, in a single layer if you can, somewhere cool, dark and dry with good airflow. Well-cured yellow onions keep for months this way — they are the longest-keeping onion there is.
Only store bulbs that are firm and sound; any soft, damaged or thick-necked bulb should be used first. Check the stored crop every few weeks and remove any bulb that has gone soft, because one rotting onion can spoil its neighbours. Keep onions 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: yellow onions for long storage, red and white onions for fresh eating, and a row of spring onions for early picking. You can also sow sets in autumn for an early crop the following summer, where your climate allows.
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 yellow onions ready to harvest?
When the tops yellow and fall over, the bulb is well rounded with golden-brown papery skins, and the neck feels soft and papery. Maturity is typically 90–120 days.
How do I cure yellow 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 and tight. Turn them occasionally and only store firm, sound bulbs.
How long do yellow onions last in storage?
Well-cured yellow onions keep for months in a cool, dark, dry place with good airflow — they are the longest-keeping onion. Check them every few weeks and remove any that have gone soft.
Can I eat yellow onions straight after lifting?
Yes, but they taste better after curing, which dries the skins and concentrates the flavour. Young onions pulled early are good as spring onions.
Why did my yellow 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.