How To Dehydrate Onions For Long Term Storage

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We have three main ways we store our onions.  Those that will get used fresh throughout the year will get braided and hung in the root cellar.  Those that I want for canning but are ready before other fresh ingredients will often get prepared for canning and then frozen while they wait.

Others that will be used in soups and other cooking will get dehydrated.  This takes up far less space than hanging them in the root cellar.

Before You Start Dehydrating Onions

There are a couple of things to consider before you begin to dehydrate onions.

If at all possible, set yourself up to do this outside.  I promise you–it may seem as though it isn’t too bad when you first start, but once these babies get going, you’ll wish they were never in the house if you tried this.  All this coming from a woman who loves the smell of onions.  Seriously.  Just try your hardest to find somewhere outside for this task.

If at all possible, delegate a dehydrator for your onions and nothing else.  I have an Excalibur that I use for everything–except for onions.

Onions have an odor that lingers, even after the dehydrator is clean.  You can get the smell out by cleaning it good enough for storing your dehydrator when it’s done.  In fact, for the rest of the year I can’t smell it on the dehydrator at all.  But once you turn it on again, it will come back.  The smell and taste will cling to the next thing you dehydrate–and possibly the next thing, and the next thing…

I have a smaller dehydrator that I use for onions.  It isn’t fancy, but it gets the job done.

If you can’t possibly designate a dehydrator just for onions, ask your friends if they have one just for this purpose you can borrow (I borrow my friend’s dehydrator for jerky during deer season just so it doesn’t have to be shared either).

If all else fails, plan to dehydrate potatoes as soon as you are done with your onions.  Lots of potatoes.  It helps to take the smell out, and most people who like onions don’t mind a slight onion taste to their potatoes.

I always plan this as the last thing I will do at night so that the dehydrator will run all night.  Outside.

If Your Dehydrator Doesn’t Have A Solid, Flat Tray

The dehydrator I use for my onions does not have solid trays or liners.  If I tried putting chopped onions in it, they would fall through.

How to dehydrate onions, plus how to adapt a dehydrator that doesn't have solid trays. This blog has tons of cool preservation tips!That’s okay.  I have a fast & easy trick to fix that.  Before I got my Excalibur, I had to use this technique for fruit leathers as well.

Cut a piece of wax paper to fit the size of your tray.  Fold your wax paper into fourths, and then cut a hole out of the middle just big enough to fit over the whole running up the center of your dehydrator.

I’ll dehydrate about 300 onions a year on 4 trays.  These 4 pieces of wax paper are usually enough to last through the entire week of dehydrating.

For anyone trying to estimate how many onions you can do at a time, I can fit one large onion on each of the 4 trays, or 5-6 small onions dispersed among the 4.

Chopping Onions For The Food Dehydrator

Make sure to clean your onions in cold water.  Cut off the tops and bottoms and remove the outer skins.

When you’re ready to chop your onions, you have a choice.  I have seen many articles about how you can use your food processor to do this.  I will admit this would be faster.  However, I’ll tell you why I do it by hand.

When you do it with a food processor, you have to stand right there, pulse it slowly (I imagine) and make sure not to make onion juice, which I believe would happen quite fast.  When I look at pictures from when food processors were done, it appears some pieces are very small, and some are a bit larger.  And, I hate to say it, but when you’re all done, the onions just aren’t as pretty as if you’d done it by hand.

Once I’ve chopped them by hand, I do my best to make sure they are evenly distributed on their tray.  Make sure you don’t have layers sticking to each other.

Every time I finish a layer it I immediately add it to the dehydrator layer and put the lid on.

How to dehydrate onions, plus how to adapt a dehydrator that doesn't have solid trays. This blog has tons of cool preservation tips!Once all your layers are done, turn your dehydrator to 135 deg (or whatever your vegetable setting is), and leave it on overnight.

I have read several articles stating they are done in five hours.  I leave mine on overnight–about 12 hours, and they are perfect.

They do stick a bit to the wax paper, but come off easily.

Storing Your Newly Dehydrated Onions

Since I dehydrate my onions straight out of the ground before they have cured, I place them in a Ziploc bag and then put them in a freezer for two weeks.  This isn’t a necessary step if you are buying onions from the store that have been cured.

Then I can take them out and store them in either a tin gallon container (the ones I will use first), or in a gallon ball jar.  (See how I seal the glass containers here.)

When I’m ready to use these, I just soak them in hot water for 15-20 minutes. After they are soft, I’ll drain the water and they are ready to go.  I only use dehydrated onions for cooking.  I would never use them on something the same way as I would fresh (raw) onions.

When preserved this way, these always last me until the next year’s harvest.

How to dehydrate onions. This site has tons of cool preservation tips!

*Money saving tip:  Don’t buy onion powder or onion salt!  If you can dry your own onions, you can make your own salt & powder.*



  1. Once the onions are dried, will they do well if you put them in a food processor to mince? So, instead of chopping them in the beginning, to just slice them, then put through the food processor.

  2. Is it true that they smell truly strong if they are made in the kitchen?

    • Yes, I meant every word–do it outside if you possibly can. I tried to do it inside once, and I didn’t get very far before I had to take them outside. It was pretty overwhelming.

  3. Thanks for this post about the time required to process a large amount of onions. Love the tip about using wax paper!! In years past I have used my handy ‘Vidalia Chopper’ (find on Ebay or Walgreens *As Seen On TV*) . That little chopper makes fast work of the chopping and the pieces are precise and pretty. Great gadget.. I keep one the camper too. We also keep a few bags of chopped onions in the freezer ready for soups/stews.. Thanks again for the post!

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