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How Long Do Onions Last?

You come home with a big bag of onions you want to get the most out of. How long do onions last?

Or maybe your onions tend to rot or spoil way earlier than you’d think they should. And you want to learn what you’re doing wrong or how can you improve your storage practices.

If that sounds familiar, you’re in the right place. Keep reading.

In this article, I talk about dry onions – the most popular kind of onions out there. The advice below works for both yellow and red onions.

Onions
Onions

How To Store Onions

Store whole onions in a cool, dry, and well-ventilated place, and peel them right before using. Once you chop or dice an onion, keep the leftovers in an airtight container in the fridge.

That’s the gist of it. Let’s talk about all of that in a little more detail.

First, let’s cover temperature and storage place.

The optimal temperature for storing onions is between 45 and 55°F (about 12°C to 15°C) ([ONOA]). If you happen to have a cold cellar or pantry that maintains similar conditions, good for you. If you don’t, a pantry or a cupboard in the kitchen is the next best thing.

Too warm storage conditions may result in the onions sprouting. Onions that have sprouted are safe to eat, though.

Cutting onions on a cutting board
Cutting onions on a cutting board

Next in line is how you store these root veggies.

You should keep your onions dry, so it’s best to keep them in a mesh bag, a wire basket, or a ventilated bag. Some even use old nylon stockings for that, tying a knot between each onion.

And while we’re at it, keep onions away from produce that release moisture, like potatoes ([ONOA]).

Don’t store onions in plastic bags, as these limit air circulation and trap moisture ([ONOA]). Or, at the very least, open the top and poke some holes to let the air circulate.

Finally, if you have a bunch of onions in storage, inspect them every couple of days and discard ones that are starting to spoil.

When it comes to cut-up onions, all they need is a cold temperature and a good seal. An airtight container in the refrigerator provides precisely that.

Chopped onions
Chopped onions

How Long Do Onions Last?

Onions last between a couple of weeks and a couple of months, depending on the cultivar and storage conditions. If you keep them in the pantry, they last about two weeks in warm months and up to a month in cold months.

Chopped or diced onions last up to a week in the fridge.

On most websites, you can read that onions last for two to three months. That’s true, but only if you store them in the ideal conditions I described above.

If you keep them in a ventilated basket in the kitchen or pantry, that storage time is cut in half. Or at least that’s been my experience.

Sliced onions and kielbasa
Making lecho: sliced onions and kielbasa

Because of that, I switched to buying 4 or 5 onions every week or so instead of buying large bags of onions.

Avoid stocking up on onions and buy only as much as you need in the next two weeks or so. Especially, if your onions tend to go bad quickly because of so-so storage conditions.

Another thing is that some onion cultivars are good keepers, while others not so much ([ISU]). And since you neither know which one you’re buying nor want to memorize a storage time chart, it’s best to stick with one safe period.

Bunch of onions
Bunch of onions

How To Tell If an Onion Is Bad?

Throw out onions that:

  • Are rotten. Please note that onions sometimes start to rot from the inside. Because of that, it’s best to cut old ones in half just to make sure they’re okay.
  • Have large patches of black or gray mold. Mold is rarely a good thing, except maybe in some cheeses.
  • Are soft or slimy. If the veggie has lost a lot of water, it’s no good.
  • Smell off. If your onions have a putrid smell, or the odor is much stronger than usual, they’re done for.

You can cut off the spoiled areas if they’re small (with some extra), but at a certain point, you have to accept your losses.

Some loose skins on the outside are fine ([ONOA]). The same is true for sprouting, just like sprouting potatoes are safe to eat.

Cut onions closeup
Cut onions closeup

Summary

  • Store onions in a cool, dark, and well-ventilated place. If possible, keep the temperature between 45 and 55°F (about 12°C to 15°C).
  • If you keep onions at ambient temperature (e.g., in the pantry), they last about 2 to maybe 3 weeks in warm months, and about a month in cold months. If they sit in your kitchen, where it’s quite hot at times, the storage period is even shorter.
  • Transfer leftover chopped or diced onions into an airtight container and put it in the fridge, where they can sit for up to a week.

References

Cooked chopped onions
Cooked chopped onions, a starter for most chicken broth based soups