How to Store Onions

By Luna Regina | Updated
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It’s important for any cook — amateur or otherwise — to know how to store onions the correct way. After all, onions are among the most ubiquitous and useful vegetables out there. Their flavor makes an excellent companion for just about any recipe that you may have in mind.

You can’t go wrong having an ample supply of fresh onions in your kitchen!

So, here’s how you can keep all of your onions for longer and maintain their fresh flavor the whole time.

How Long Do Onions Last?

When stored in ideal conditions, onions can last up to 3 months. At room temperature, however, onions’ quality will begin to plummet in only about a week.

Therefore, unless you’re certain that you can use up all of your onions in a week's time, you must store them right. You will save some money that would have otherwise been spent replacing the spoiled onions. Additionally, you will also reduce food waste.

How to Tell If Onions Are Bad?

We can’t know how well our food is preserved if we don’t also know when it’s spoiled. Fortunately, it is very easy to tell when an onion has gone bad.

When an onion begins to spoil, dark spots will grow on the skin. That’s black mold.

How to Tell If Onions Are Bad
The black spots found here aren’t dirt. They’re fungal colonies.

Surprisingly, a moldy onion is still relatively safe to eat, as long as it’s still firm and you can remove the dark spots on the skin. However, we still don’t recommend you try and salvage them. Aspergillus niger — the fungus that causes this phenomenon — can induce an allergic reaction in some people. It can also cause otomycosis, a fungal ear infection.

It’s best to discard moldy onion bulbs altogether.

Aside from the bulbs’ coloring, you can also tell by texture. If the onions are soft and mushy, they definitely have gone bad.

Lastly, spoiled onions will have a distinct smell. It’s difficult to describe the scent since onions don’t smell very good to begin with. However, if you feel like the smell is “off,” trust your instincts and do away with it.

Best Ways to Store Onions

Onions are fairly easy to store as long as you stick to the three main rules: cool, dry, and dark.

First, look for someplace dry and away from direct sunlight. It should also have a cool temperature range between 45 and 55°F (7.2 and 12.8°C). If you live somewhere with a cool climate, it’s not difficult to find a suitable spot. Typically, the cellar, basement, garage, or sometimes even the attic will do.

However, if you're somewhere with a hotter climate, just store the onions in the fridge.

In the worst case scenario where you don’t have the fridge space, store the onion bulbs at room temperature. Follow the other two points (dry and dark) and the onions will last for an extra week.

Once you have located the spot, pack your onions into net bags. You can find these online or at your local grocery store.

The reason why net bags are preferable is because unlike solid baskets or boxes, they have excellent ventilation. Onions aren’t quite “dead.” They’re still living despite having been dug up from the ground. If you let them suffocate and wilt away, they will spoil even quicker.

Best Ways to Store Onions

Hang the onion-filled net bags off the ground. The bulbs will do best if they’re not resting on a solid surface.

How to Store Onions From the Garden

1. Curing

If you grow your own onions in the garden, the first step after harvesting is to cure them. Curing simply means drying the outer skins of the onions. This will significantly extend their shelf-lives.

You don’t have to do this for store-bought onions. They’re mostly cured in the factory already.

You can dry the onions on shaded racks. If you have a greenhouse, you can lay them out on newspapers to dry.

Arrange the onions so that there’s plenty of space between them. Ensure that there is proper ventilation, as well. This way, all of the moisture on the onions can be wicked away. This process also has the added benefit of preventing mold or rotting.

How to Store Onions From the Garden
Onions being cured on a rack.

Curing takes about two weeks to complete. You will know your onions are ready when the skins turn paper-like. Check the leaves and the roots, as well. They should all be shrivelled up and dried out.

Cut off the roots and remove the outer skins. After that, you can proceed to store the bulbs.

2. Storage

Bulbs that feel soft in the hand or which have thick necks should be used right away instead of stored. They generally don’t last long in storage.

Like earlier, put your cured onions into net bags. Hang them off of the ground in a cool, dry, and dark place.

How to Store Onions in the Fridge

How to Store Onions in the Fridge

If you cannot find a place in your house that’s cool enough to store your onions, put them into the fridge. But one thing of note: it’s not recommended to store whole onions in the fridge.

Store-bought onions are often already cured. And, like we mentioned earlier, even if you harvest your own garden-grown onions, curing is a crucial step before storage. After onions are cured, their moisture content will be very low. That’s why they can last for longer.

Inside of the fridge, cured onions are exposed not just to cold temperature but also high humidity. Once moisture is reabsorbed into the onions’ cells, they turn mushy and can spoil faster. As a result, you should only store processed onions in the fridge (peeled, sliced, or diced onions).

Storing onions in the fridge is simple. You can either wrap them up using food wrap or put them into resealable plastic bags. Then, put them into the fridge.

How to Store Onions in the Freezer

If you have whole onions, chop or dice them into ¼-inch to ½-inch pieces. Then, put them into freezer-safe plastic bags. Before sealing, squeeze out as much air from the bags as you can.

When the bags are sealed, put them on a baking sheet and put them into the freezer overnight.

Check on the onions the day after. If satisfied with the way they froze, label each bag with the name and date for easier tracking. Put back into the freezer for long-term storage.

Although frozen onions can last up to a year, we recommend that you use them up within 8 months.

How to Store Cooked Onions

Cooked onions can either be stored in the fridge or the freezer. It all depends on how long you want to store them.

In the fridge, they last 3 to 4 days. In the freezer, the expected lifespan is between 8 months and a year.

The freezing procedures are the same as the ones outlined above.

Conclusion

It’s not so difficult to learn how to store onions, after all! Onions are pretty forgiving compared to other vegetables, so there’s no need to be anxious. As long as you follow these steps, they will be fine and fresh for your enjoyment.

Luna Regina

A writer and entrepreneur, Luna’s day doesn’t start at the computer keyboard, but in the kitchen. Half of her working hours are spent on mixing ingredients for her recipes. The other half involve working with the tech team to research and test the tools and appliances that promise to make kitchen work effortless and mess-free. From a kitchen knife or water filter to the Instant Pot, if it can help save time and effort for the home cook, Luna and her team are on it. Luna’s extracurricular pastimes include camping, travel, and photography.

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