Get dos and don'ts for storing this flavorful allium.

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Do you ever walk by those big bags of onions at the market and wonder if they're actually a bargain? They are! But only if you know how to properly store all those alliums. Sure, onions are versatile and easy to use—Vidalia Onion Tart, Onion Rings or Stuffed Onions anyone?—but how quickly can any of us use a 3-pound bag? That's a lot of onions. Thankfully, with a little TLC you can maximize the shelf life of onions—they can last two to three months if stored properly—and we've got everything you need to know. Read on for the dos and don'ts of storing all kinds of onions—white, yellow and red—including how to store peeled, halved, sliced or diced onions, as well as how to freeze cut onions so they last even longer.

An image of an onion on a tan background next to details of a sliced onion
Credit: Getty Images / lacaosa / Image Source

Do Store Whole Onions in a Cool, Dark and Dry Place

It might seem like a good idea to refrigerate whole onions, but onions absorb moisture easily and inside the fridge is a humid place, which makes for mushy, sprouted or even spoiled onions. Instead, keep onions in a cool, dry place with good ventilation, such as a pantry, cellar or even the garage. It also helps to keep onions in the dark because the lack of sunlight helps reduce changes in temperature and humidity.

If you don't have a pantry, cellar or garage, onions are best stored in the fridge, where they will last up to two weeks, or at room temperature, where they will last about one week.

Don't Store Whole Onions in Plastic Bags

Another way to ensure good ventilation is to avoid using plastic bags, which trap moisture. Keep whole onions in an open basket or bin, a mesh bag or a loose paper bag to ensure good air flow. If you did buy onions in a net bag, that's a great way to store them, as it keeps them together but allows for air to circulate. There may also be a label on the bag, which makes it easy to add a date and track how long you've been storing those onions. A paper bag makes this easy, too.

Don't Store Onions and Potatoes Together

Though they play together nicely in the oven or slow cooker, potatoes and onions are not friendly storage mates and tend to go bad more quickly if stored together.

Do Refrigerate Peeled, Halved, Sliced or Diced Onions 

Once onions are peeled or cut in any way, they are best stored in an airtight bag or container in the refrigerator. Peeled whole onions should last 10 days to 2 weeks, while cut onions should last about 10 days. If using a container, consider glass, which doesn't absorb odors like plastic.

Do Freeze Sliced or Chopped Onions

While it's cumbersome to freeze whole raw onions, sliced or diced onions can be frozen for up to six months (learn how to freeze onions here). Store them in airtight freezer bags—labeled and dated so you can keep track of them—and consider double bagging to keep onion odors in and other odors out.

Onions thaw quickly but you can submerge the bag in a bowl of cold water to speed up the process. They won't be quite as crisp as fresh onions, but frozen onions are great in cooked dishes, such as soups, stews and casseroles.