Last Updated: May 13, 2021

We all love onions, not just for their culinary usefulness but also their impressive shell life at room temperature.

But persistent as the onion is, it still doesn’t retain its impressive storage capacity the very moment you slide through a knife to cut it in halve or slide and dice it for the rice pilaf at noon.

It becomes highly perishable and susceptible to bacterial contamination, just like any other food out there but never really any worse, and the only safe way to guarantee its safety for a few more days is by opting for cold storage. And that’s exactly what we’ll be exploring today!

How to store a half cut onion

Storing a half cut onion is simple, follow the steps below.

Hope it’s a high quality onion?

The best way to end up with an onion that is at least manageable in the flavor department after its storage life in the fridge is to start with a high quality onion in the first place. This will also ensure that the onion retain structure and quality more and also store longer.

Package the cut onion inside a plastic bag

After cutting the onion in half, place the remaining portion inside a plastic wrap or in a zipper lick bag or any air tight container and package tightly. Keep in the refrigerator away from sensitive vegetables (those that can easily pick up the smell of the onion, and those that can be influence in their ripening by the presence of an onion) for up to 2 weeks. Note, even with your effort to keep vegetables apart from the onion, it still wouldn’t stop the onion smell from diffusing all over the cabinet. So you’ll still have some traces in these sensitive food.

If you onion on a daily basis, you can skip the refrigeration process and simply turn the fleshy side of the onion on a paper and leave at room temperature for no more than a day.

Also, note that some onion cultivar and varieties will keep for longer than others, so make sure to check on the onion on a regular basis to makes sure they haven’t gone bad.

To use the onion, simply slice the dried surface of the exposed flesh and incorporate into the recipe as directed.

How to store chopped onion

Just like for half cut onion, the better the onion quality the better results you’ll get from refrigeration.

After chopping the onion on a clean board, with clean hands and a clean knife, go ahead and package the chopped onion inside an airtight packaging like the ones mentioned above and then keep in the crisper for no more than 3 days. It’s 3 days in this case because a chopped onion, having no external parts to protect it from excessive respiration will spoil much faster.

When it’s time to use them, rinse them well to rid them off a certain compound called “thiosulfinates” that must have formed during storage which will cause the onion’s to acquire a pungent odor and flavor.

Alternatively, for chopped, diced or sliced onions, you can always freezer them to get them to store for longer. And if you ever wanted to store your fresh bulbs of raw onions for longer, you’ll also have to dice, slice or chop them first before storage.

For the storage, you want to, first, use mature and quality onion as always, pack them on one layer on a cookie sheet with sides and pop them in the freezer until they turn frozen. Then package them inside an air tight packaging and stuff inside the freezer for up to 8 months. This method ensure that you can pour out the onion in their individual pieces whenever you need them. When you don have time for this method however, you can always package them inside the freezer bag directly and store them flat with as much air pressed out from the bag.

For best results, ensure to use the onions as early as possible since an onion is the type of veggie that losses it’s freshness easily with time. Also, you can use the onion from frozen state directly, or thaw allow to thaw for a little while before using.

Best packaging for freezing cut onions:

  • Freezer bags
  • Freezer paper
  • Heavy duty aluminum foil. Avoid wax paper or parchment paper as these don’t perform well during long term storage.
  • Plastic containers having a snowflake symbol.

Avoid using these type of containers for storing onions in the freezer.

  • Bread bags
  • Dairy containers
  • Cheese carton
  • Food storage bags.

These would fail during long term storage and will cause a serious degradation of quality of the onion. You wouldn’t want to use that in a recipe, trust me.

The perks of freezing of chopped onions

Freezing chopped onion isn’t without its own perks, and this also applies to short term storage in the refrigerator. When you refrigerate an onion, it naturally becomes soft and soggy a lot faster that if you had left it to sit on the counter – which isn’t an option for cut onion. Adding to that, it also loses some of its flavor and adopts on a metallic, sour and harsh kind of tone as opposed to the fresh taste of fresh onion.

But that’s when you refrigerate, what about freezing? Things get even worse with freezing, because this time, you also loose structure and everything times two. So your frozen onions are best purposed for recipes that require cooking them, rather than relying on them to be the start ingredient of your dish. You’ll be heavily disappointed.

Frequently Asked Questions

How to store cut green onions

Store cut green onion in an air tight container in the crisper of the refrigerator and away from potatoes for no more than 3 days.

How to store cut red onions

Store half cut red onion in the fridge in a plastic bag sealed for airtightness for up to 2 weeks. For slices, or diced onion, store them inside such container for up to 4 days.

How long can you keep cut onions in the fridge?

Half cut onion will keep in the fridge for no more than 2 weeks, but deterioration could happen much faster depending on the variety of onion. Sweet onions for example, have more water content their other types of onions, and thus will spoil much more quickly. For slices and dices of onions, store them under air tight packaging for no more than 3 days.

How long do cut onions last at room temperature?

Cut onions can last no more than a single day on the counter, flipped cut side down on a clean paper and stored in a dark, cold, dry and well ventilated room. For slices, they will not last for more than 2 hours because they are more susceptible to pathogenic bacteria due to their more delicate nature.

How long can you keep onions in the fridge?

Raw whole onions should never be kept in the fridge because they will turn soft and soggy faster due to moisture transmission. They are best stored in a dark, dry, cool and well-ventilated area where they could last up to 4 months in storage.

If raw onions must be stored then they should be peeled, washed and diced or sliced and then packaged in an air tight packaging and then popped into the freezer where they would keep for up to 8 months but are of best quality when used earlier.

Final Verdict

Whenever you have leftover cut onion after following recipe instructions, feel free to pop them inside the freezer to preserve them for much longer. They last longer there and stay safer.

To refrigerate leftover cut onions,

  • Package half cut onions inside an air tight container and put inside the refrigerator for no more than 2 weeks.
  • Package diced or chopped onion inside an airtight container and place inside the crisper drawer for no more than 3 days.

To freeze left over cut onion,

  • Dice or chop them, then tray freeze them by spreading them on a cookie sheet in one layer and then putting them inside the freezer until they turn frozen. Then, package inside an airtight container and freeze for up to 8 months.