How to Tell If Onions Are Bad
A bad onion feels soft, mushy, or wet, and often has dark mold under the papery skin or a sour, rotten smell. If it’s firm with just a few green sprouts, it’s usually still fine to use.
Signs Onions have gone bad
- Soft, mushy spots. Squeeze the onion gently. A good one is rock firm all over. A spot that gives way like a bruised fruit means rot has started inside.
- Dark mold under the skin. Black, gray, or dusty-looking patches beneath the papery layers are mold. If it’s only on the outer layer, peel that layer off and check the next one. If it has reached the inner rings, toss the whole onion.
- Slimy or wet layers. Rings that feel slick or leak liquid when you cut in are breaking down from bacteria. Slimy onions go in the trash, not the pan.
- Sour or rotten smell. Fresh onions smell sharp and oniony. A sour, musty, or garbage-like odor means it has turned.
- Hollow, dried-out, or shriveled center. A very light onion with a sunken top and mushy or brown center has been stored too long. Cut it open before you commit, and toss it if the inside is brown and wet.
- Long sprouts with a soft bulb. A few green shoots on a firm onion are okay. If the bulb has gone spongy because the sprout used up its insides, discard it.
Looks weird, but it's fine
- Short green sprouts. The onion is trying to grow. If the bulb is still firm, trim the sprout off and use the onion. The flavor may be a little stronger.
- Dry, flaky outer skin. Papery, peeling skin is normal. Just remove it.
- A few dark specks on the outer skin that wipe away. Some surface dirt or dry dark flecks on the outermost layer are harmless once peeled, as long as the layers underneath are clean and firm.
How long do Onions last?
| Where | How long | Note |
|---|---|---|
| Pantry (cool, dark, ventilated) | 1–2 months | whole, unpeeled |
| Fridge | 2 months | whole; 7–10 days once cut |
| Freezer | 10–12 months | chopped, in freezer bags |
How to store them
- Keep whole onions in a cool, dark spot with airflow, like a basket or mesh bag. Don’t seal them in plastic.
- Store them away from potatoes. Potatoes give off moisture and gases that make onions sprout and soften sooner.
- Wrap cut onions tightly or keep them in an airtight container in the fridge, and use within a week.
Use it up before it turns
Frequently asked questions
Can you eat a sprouted onion?
Yes, as long as the bulb is still firm and has no mold or sour smell. Cut off the green shoot and use the onion soon. If the bulb is soft or hollow, toss it.
Is it safe to cut mold off an onion?
If mold is only on the dry outer skin, peeling away those layers is fine. Once mold or softness reaches the inner rings, the whole onion should go, since onions are moist and mold can spread unseen.
Why does my onion have black stuff under the skin?
Black powder between the layers is usually a common mold called black mold or Aspergillus niger. Peel off the affected layers and wash your hands. If the inner rings are clean and firm, the rest is usable, but when in doubt, throw it out.
More food freshness guides
General guidance based on USDA FoodKeeper. Storage times are estimates and conditions vary. When in doubt, throw it out.