How to Tell If an Onion Is Bad

Do you know how to tell if an onion is bad? Better yet, do you know how to read the signs leading up to a bad onion?

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Have you ever reached into the pantry to grab an onion and encountered a texture you weren’t expecting? It happened to me when an onion rolled out of its bag and hid in the far corner of the cabinet. I only have one word to describe the experience: Yuck! The onion had literally melted in its skin and sat there, squishy and unforgivingIy stinky, in a pile of liquid.

We don’t recommend you wait to experience a bad onion. Instead, learn how to tell if an onion is bad by reading the telltale signs leading up to spoilage. This advice applies to most types of onion: sweet onions, shallots, or yellow, white and red onions. Fresh alliums in the onion family (like green onions, spring onions, ramps, leeks or chives) have a different set of rules and a shorter lifespan.

Signs Your Onion Has Spoiled

If your onion has gone bad, it will be pretty obvious. Squishy onions should be tossed into the trash without a second’s thought. The same can be said for stinky onions or onions that have excess moisture.

The less obvious signs are small wet spots, brown spots, or a softened texture. If these spots can be removed from a section of the onion, leaving the rest of the onion looking “normal,” it’s probably safe to cook with it. The same can be said for a sprouted onion that has no other signs of spoilage. It’s okay if you don’t want to eat the sprouted part; you can cut the onion in half to remove the sprout and any remnants of the shoot. But if you observe any signs of mold, or if you have any doubt at all if the onion is still safe to eat, it’s best to toss it.

By the way, sprouted garlic is usually safe to eat, too.

How to Pick Good Onions

We define a “good” onion as one that can be stored for several weeks in the pantry (just keep in mind these foods you shouldn’t store together). Look for onions with a firm texture and dry, papery skins. Avoid onions that are soft or exhibit brown spots. You’ll also want to avoid any onions that are sprouting. Sprouted onions are usually still good to eat, but they won’t last as long.

Tips for Storing Onions

How to store whole onions

Store whole onions in a cool, dry, ventilated spot that’s out of the sun, like a pantry or cabinet. They’ll last anywhere from several weeks to several months, depending on the temperature inside your storage area. Avoid storing potatoes and onions together, as the pair will speed up each other’s spoilage. The potatoes will sprout faster, and onions will soften and liquify next to potatoes.

You don’t want to keep onions in the refrigerator either, as the cold and humidity can cause onions to develop moisture spots and soften their texture. Fresh onions—such green onions, spring onions, leeks or chives—should be stored in your refrigerator’s crisper bin and usually only last about a week before they start getting slimy. An onion storage container might come in handy.

If you were keeping whole onions in the fridge, read up on other common foods you’ve been storing wrong.

How to store chopped onions

Once an onion has been peeled and cut, it’s best to store it in the refrigerator. Wrap any unused onion halves in plastic wrap or place them in an airtight container. We like using glass containers because they don’t absorb odors. Chopped onions are best stored in airtight containers or in a resealable bag. Properly stored, these onions are good for 7 to 10 days.

How to freeze onions

Onions freeze really well, but only if you plan to cook with them. Frozen onions lose their crisp texture, so they’re not ideal for making pickled onions or other raw applications like salads and rice bowls. To freeze onions, chop them into similar-sized pieces and place them in a freezer-safe bag. Pack the onions flat so you can break off a section and use it as needed, rather than thawing the whole thing. Frozen onions will last up to a year, but they start to lose their quality around the eight-month mark.

Recipes to Use Up Your Onions
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Lindsay D. Mattison
Lindsay is a professional chef, recipe developer, writer and developmental editor. After years of working in restaurant kitchens, she turned to writing to share her skills and experience with home cooks and food enthusiasts. She's passionate about using local, organic ingredients and teaching others how to incorporate seasonal food into their diet. Lindsay still cooks professionally for pop-up events, writes for several publications and is the co-author of two books about Ayurveda.