Do Onions Go Bad?

So you’ve stocked up on onions on the farmer’s market, and soon you’ve realized you bought much more than you can use in a reasonable time. Do onions go bad?

Or maybe you used to buy only a few bulbs at a time, and there’s going to be this big sale in a few days. And you’re wondering how much can you buy so they won’t spoil in storage. That begs the question: how long do onions last?

While onions are a kitchen staple in many households, it’s always good to learn a bit more about fundamentals such as storage, shelf life, and going bad. Most of us never do that, and we just follow in our parents’ or grandparents’ footsteps. And that’s not always ideal.

If you think you could learn a thing or two about onions, read on.

Unpeeled yellow onions
Image used under Creative Commons from Mike Mozart

How to Store Onions?

Storing onions properly is quite similar to storing garlic or shallots. The three factors to consider are temperature, humidity, and air circulation.

When it comes to the first one, cool (but not cold) temperature is ideal, so a pantry or a dark cabinet in the kitchen that’s away from the stove will work. To take care of the second factor, make sure the place is dry, and there are no sources of moisture near.

Warning

Don’t wash the onions before putting them in storage.

For air circulation, make sure the bag you store the onions in allows free airflow. If it’s a brown bag, punch some holes and leave the top open. Or use a bowl or a container without a lid and transfer the veggies there.

A plastic bag isn’t a good option for storing onions, so I’d suggest you use one of the other options. And try not to stack multiple layers of onions on top of each other. The air must circulate freely, so the onions are nice and dry while in storage.

Last but not least, keep onions away from produce that emits ethylene, a chemical that accelerates ripening (and spoilage) in fruits and veggies. Tomatoes and bananas are such fruit.

Once you sliced or chopped the onions, the fridge is where you should store them. Put them in a freezer bag or an airtight container. This way the veggies won’t absorb any moisture from the environment, won’t dry out, and their smell will be trapped inside that container.

Peeled shallots
Image used under Creative Commons from Ruth Hartnup

How Long Do Onions Last

Like garlic, onions have a fairly long shelf life. Properly handled, fresh whole onions can last for 2 to 3 months in the pantry, sometimes even longer. It all depends on how well you store them.

If you keep them around for a prolonged period, but hardly ever use, it makes sense to take a look at them every other week. Look for ones that are bad or starting to go bad, and toss them out, so others won’t pick up the bacteria.

When it comes to sliced or chopped onions, they last quite some time (for a cut veggie) too. That means they should retain quality for about a week in the fridge. So if you’re prepping some veggies on a Sunday evening, you can slice or dice your onions and have them ready to go throughout the week.

 PantryFridge
Fresh whole onions2 – 3 months 
Sliced or chopped onions 1 week
Onions, garlic, and pasta
(credit: Heather Ford)

How to Tell If Onions Are Bad?

When shopping for onions, always choose the clean, firm ones with no sprouts. If the onions have green stems sprouting on them, they are not freshly harvested. Check for brown, black, or soft spots. Onions with bruises or black/brown spots are more likely to spoil.

Info

A few layers of loose and coarse outer skin is normal (just like it is with brussel sprouts).

If you store an onion for a prolonged time, you might have to peel a few dried layers before you get to the good stuff. Also, from time to time you might stumble upon a layer in the middle that is brown and sometimes slimy. That’s rare but quite normal, and all you need to do is to discard that section and then some, to be safe.

A bunch of yellow onions
(credit: Lars Blankers)

When it comes to checking the onions for quality and freshness, the firmness of the flesh is the primary indicator. If the onion feels spongy or abnormally soft, throw it out. Same thing if there are dark spots on the veggie or the aroma is somehow off.

All in all, if it’s firm and looks healthy, chances are it’s perfectly fine. If you’re questioning if it’s okay or not, err on the side of caution and get rid of it.