Onions
Whole onions keep 1 to 3 months stored cool, dark and airy. Cut ones only about a week, refrigerated and airtight.
Why dry storage decides
Onions are among the longest-keeping vegetables. Whole, unpeeled onions with dry skins stay firm and good for one to three months stored cool, dark and airy. The key is keeping them dry — moisture is their biggest enemy and makes them rot or sprout. An airy basket or mesh bag in a cool spot is ideal, while a sealed plastic bag is the fast route to spoilage.
Once an onion is cut, the picture changes: the cut surface dries out and gives bacteria a way in. Cut onions therefore belong wrapped airtight in the fridge and keep about a week there. Peeled or chopped onions should be used up promptly. Spring onions and shallots are more delicate than regular cooking onions and keep less time.
A classic storage mistake is keeping them near potatoes: both give off moisture and gases that make the other spoil and sprout faster. Onions and potatoes should be stored apart. Whole onions also do not need the fridge — the moisture there tends to make them soft. A cool, dry pantry or cellar is the better place.
Variety matters with onions too: well-cured, dry-skinned storage onions keep longest, while mild sweet onions or red onions with more water should be used a little sooner. If you store larger amounts in autumn, check the supply regularly and sort out soft or rotting onions at once, before they spoil the rest. A single rotting onion in the bag can quickly take several others with it, and dried outer layers are no cause for concern — they protect the onion and come off easily.
How do I spot bad onions?
Onions show their state quite clearly:
Soft, brown or mushy areas point to rot. A fresh onion is firm and dry.
A musty, rotten smell means spoiled. Dark, damp layers inside point the same way.
A green shoot is edible but shows fading quality. Grey-black mould means discard it.
Shelf life at a glance
State and storage decide between days and months:
| State | Shelf life |
|---|---|
| Whole onion, cool & dry | 1–3 months |
| Cut, refrigerated airtight | about 1 week |
| Peeled/chopped, refrigerated | a few days |
| Spring onions, refrigerated | a few days to 1 week |
Store them right
The right storage keeps onions longest:
Dry and airy — in a mesh bag or basket in a cool, dark spot, not sealed film.
Away from potatoes — each makes the other rot and sprout faster.
Cut ones in the fridge — wrapped airtight, they keep about a week.
Do not chill whole ones — in the fridge whole onions turn soft from moisture.
Common myths
A few myths surround onions:
A persistent myth with no scientific basis. Cut onions are safe, but should be stored refrigerated and airtight.
Better not — they make each other spoil and sprout faster.
No — cool and dry in a cupboard is better. In the fridge they turn soft from moisture.
Leftover cut onions freeze well — diced and raw, straight from the freezer into the pan. And fried crispy onions or onion confit keep several days chilled and add quick flavour to many dishes.