Can You Freeze Onions?

Yes, and they are one of the easiest vegetables to freeze: chopped or sliced onions need no blanching whatsoever. Just dice them, freeze them on a tray, and bag them. They thaw soft, so they are strictly for cooking, not for raw garnish, and they keep their best flavour for a few months. Whole bulbs are the exception — blanch those first.
Can you freeze onions?
Yes — it freezes well- Peel and chop or slice the onions to the size you usually cook with — diced, half-moons, or rings.
- Spread the pieces in a single layer on a lined tray and freeze for an hour or two until firm.
- Tip the loose frozen pieces into a bag or container, press out the air, and seal it tightly.
- Double-bag or use an airtight container so the smell does not travel to other freezer items.
More in this group: Freezing vegetables
Frequently asked questions
Do you need to blanch onions before freezing?
Not if they are chopped or sliced — raw diced onions freeze well with no blanching at all. Only whole onion bulbs need a blanch (3 to 7 minutes until the centre heats through) before they go in the freezer.
How do you stop frozen onions smelling up the freezer?
Seal them properly. Use a thick freezer bag with the air pressed out, or an airtight container, and double-bag if your freezer is small. The strong aroma only escapes when the packaging is loose or thin.
Can you freeze caramelised or sautéed onions?
Yes, and they freeze beautifully. Cool the cooked onions, portion them into small bags or an ice-cube tray, and freeze. Drop a frozen block straight into the pan when a recipe wants a head start on that deep, sweet flavour.
Are frozen onions still good for cooking?
Very much so. They soften and lose their crunch, but in soups, stews, sauces, and stir-fries that softness is exactly what you want. Add them straight from frozen and they cook down just like fresh chopped onion.
Sources
- NCHFP — Freezing Onions — NCHFP, University of Georgia, checked 2026-06-13
- University of Nebraska–Lincoln Extension — Freezing Onions — UNL Food, checked 2026-06-13
- USDA FSIS — Freezing and Food Safety — USDA FSIS, checked 2026-06-13