How Long Onions Last in the Refrigerator and How to Store Them Properly

Whole onions last 4 to 8 weeks in the refrigerator, but cut onions spoil in 7 to 10 days

The shelf life of an onion depends almost entirely on whether it's whole or cut. A whole, unpeeled onion keeps longest—typically 4 to 8 weeks in your refrigerator's crisper drawer, sometimes longer if stored correctly. Once you cut into an onion, the clock moves much faster. A cut onion exposed to air will last about 7 to 10 days before it becomes soft, develops mold, or starts to smell sour.

Temperature matters more than you might think. Onions prefer cool, humid conditions, which is exactly what a crisper drawer provides. The ideal range is around 40°F (4°C), which is what most refrigerators maintain. Whole onions stored at room temperature in a pantry or on a counter last only 1 to 2 weeks, so refrigeration genuinely extends their life.

Key Takeaways

• Whole onions stored in a refrigerator crisper drawer stay fresh for 4 to 8 weeks, while room-temperature storage cuts that to 1 to 2 weeks.
• Cut onions last 7 to 10 days in the refrigerator when wrapped tightly in plastic wrap or stored in an airtight container.
• Onions release a gas called ethylene as they age, which speeds spoilage in nearby produce—store them away from potatoes, garlic, and apples.
• Signs an onion has gone bad include soft spots, visible mold, sprouting, or a fermented or sour smell.
• Peeled but uncut onions last about 2 to 3 weeks when stored in an airtight container in the crisper.

The best storage method for whole onions

Whole onions need air circulation and humidity to last their full 4 to 8 weeks. Place them in your refrigerator's crisper drawer—not in a sealed bag or container. The crisper is designed to trap moisture while still allowing some air movement, which prevents the onion skin from drying out and cracking while also stopping condensation from pooling around the onion itself.

Keep onions in their papery skin. That thin, papery layer is a natural barrier that protects the flesh underneath from moisture loss and mold. Do not wash whole onions before storing them; any moisture on the surface can encourage rot. If an onion arrives with dirt on it, a quick dry brush with a paper towel is enough.

Store onions away from potatoes, garlic, apples, and bananas. Onions release ethylene gas as they mature, which accelerates ripening and decay in nearby produce. If your crisper is small, use the vegetable compartment on the opposite side of the refrigerator, or keep onions in a separate drawer altogether.

How to store cut or peeled onions

Once you cut into an onion, the exposed flesh begins to oxidize and lose moisture. Wrap the cut side tightly in plastic wrap, pressing it directly against the cut surface to minimize air exposure. Place the wrapped onion in an airtight container or a resealable plastic bag, then store it in the crisper. This method buys you 7 to 10 days.

If you've peeled an onion but haven't cut it, the timeline is longer—about 2 to 3 weeks. Store it in an airtight container in the crisper. The peeled surface is still intact, so it doesn't oxidize as quickly as a cut surface does, but it will dry out faster than an unpeeled onion.

Chopped or diced onions have the shortest lifespan because you've exposed far more surface area to air. Store them in an airtight container and use them within 3 to 5 days. If you know you won't use them that quickly, consider freezing them instead. Frozen chopped onions last 3 to 6 months and work well in cooked dishes, though they lose their crisp texture and are not suitable for raw applications like salads.

Signs an onion has spoiled

A soft or mushy onion has begun to break down internally. Press gently on the onion's skin—it should feel firm. If your finger leaves an indent or the onion feels squishy, discard it. Softness usually means the cells have started to collapse, and the onion will taste unpleasant even if mold isn't visible yet.

Visible mold is an obvious sign to throw the onion away. Mold appears as fuzzy white, green, or black patches, usually on the cut surface or where the onion was damaged. Do not cut away the moldy part and use the rest; mold spreads through the onion faster than you can see, and eating it can cause digestive upset.

A sour, fermented, or vinegary smell means the onion is fermenting inside. This happens when bacteria or yeast colonize the onion's interior, usually because it was stored with too much moisture or in a sealed container without air circulation. Sprouting—when green shoots emerge from the top of the onion—is not dangerous, but it signals the onion is aging and will taste less sharp. You can cut away the sprout and use the onion, but it's past its prime.

Why onions last longer than other alliums

Onions keep longer than garlic, shallots, or leeks because of their structure and chemistry. The papery skin and dense layers of flesh create a natural barrier against moisture loss and microbial invasion. Garlic, by contrast, has a thinner skin and dries out faster. Leeks are mostly water and spoil within 1 to 2 weeks even in the refrigerator.

Onions also contain sulfur compounds that act as natural preservatives. These same compounds give onions their pungent smell and sharp flavor. As an onion ages, these compounds break down, which is why old onions smell less sharp and taste milder. This is not spoilage—it's aging—but it's a sign the onion is losing quality.

Organizing your crisper to keep onions fresh longer

Crisper drawers work best when they're not overstuffed. Onions need air to circulate around them, so don't pack them in tightly with other produce. If your crisper has a humidity control, set it to high (closed) for onions. High humidity keeps the papery skin from drying out and cracking, which would expose the flesh to air and speed decay.

Check your onions once a week. Remove any that have developed soft spots or mold before they can spread to neighboring onions. A single rotting onion can release ethylene and bacteria that affect nearby produce, so catching problems early protects your whole crisper.

If you buy onions in bulk, store them in layers with paper towels between them. This prevents them from touching each other, which reduces the spread of mold or bacteria if one onion begins to spoil. It also makes it easier to spot a problem onion before it affects the others.

Frequently Asked Questions

Can I store onions in the freezer instead of the refrigerator?

Yes, but only if you plan to cook with them. Frozen onions become soft and watery when thawed because ice crystals rupture the cell walls. They work well in soups, stews, and sauces, but not in raw applications like salads or sandwiches. Chop them first, freeze them in a single layer on a baking sheet, then transfer to a freezer bag. They last 3 to 6 months frozen.

Why do onions make my refrigerator smell?

Onions release sulfur compounds into the air, especially as they age or if they're cut. This is normal and not a sign of spoilage. To reduce the smell, store cut onions in an airtight container and keep whole onions in the crisper drawer, which contains odors better than open shelves. The smell will fade once you remove the onions.

Is it safe to eat an onion that has started to sprout?

Yes, sprouting onions are safe to eat. The green shoot that emerges is not toxic. However, the onion is diverting energy to the sprout, so the flesh becomes softer and the flavor becomes milder. Cut away the sprout and use the onion in cooked dishes. If the onion feels mushy or smells sour, discard it regardless of sprouting.

How do I know if a cut onion is still good after a week?

Smell it first. A fresh onion smells sharp and pungent; a spoiled one smells sour, fermented, or off. Look at the cut surface—it should be firm and dry, not slimy or discolored. If it passes both tests, it's probably safe, but if you're uncertain, throw it out. The cost of a single onion is not worth the risk of foodborne illness.

Can I store onions and potatoes together in the refrigerator?

No. Onions release ethylene gas, which causes potatoes to sprout and decay faster. Store them in separate drawers or on opposite sides of the refrigerator. If your crisper is small, keep onions in the main refrigerator compartment instead, away from the vegetable drawer where potatoes usually go.