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How to Dehydrate Onions: Easy Steps, Drying & Storage

Portrait of Susan Gast, author of Easy Food Dehydrating
Susan Gast, Author and Food Preservation Enthusiast
Susan has been dehydrating and preserving foods for over a decade, sharing practical, tested methods that help readers make healthy, long-lasting meals at home.

Cutting onions may bring on the tears, but dehydrating them gives you delicious, ready-to-use flavor without all that chopping every time you cook!

Whether you're drying fresh onions or using a bag of frozen diced onions, it's easy to make your own dried onion pieces, crispy onion flakes, or homemade onion powder.

I'll show you how to prepare, dehydrate, check, and store your onions properly—plus a few tips for handling that unmistakable onion aroma!

✅ Quick Answer: How do you dehydrate onions?
Peel and slice fresh onions into even pieces or rings, approximately ⅛–¼ inch thick, or use frozen diced onions straight from the bag. Arrange in a single layer on dehydrator trays and dry at 125–135°F (52–57°C), generally for 4–12 hours or longer, until completely dry and brittle. Allow to cool, check for remaining moisture, and store in airtight containers. Grind into onion powder as needed.

Susan Gast chopping onions on a cutting board and wiping tears from her eyes

Dehydrating Garlic and Onions:
Ventilation and Pet Safety

Dehydrating garlic or onions can fill your entire house with a powerful aroma. And let's face it—you either LOVE that smell or you DON'T!

Keep your kitchen well-ventilated. Run your range hood, open a window when practical, or position your dehydrator in a well-ventilated area. This helps prevent those strong odors from lingering throughout the house.

A note about pets: Both garlic and onions are toxic to dogs and cats if eaten, whether fresh, dried, or powdered. Keep them safely out of reach, and make sure your pets can move away from strong cooking odors, which may be irritating to sensitive noses.

One more tip: Don't dehydrate garlic or onions alongside apples or other delicate fruits unless you fancy garlic- or onion-flavored fruit snacks!

A pile of whole yellow onions with their papery skins intact

Step-by-Step Guide: How to Dehydrate Onions Like a Pro

Let's get busy learning how to dehydrate onions—fresh or frozen!

  1. Prepare the onions. Peel fresh onions, remove the root and stem ends, and discard any damaged or spoiled portions. If you're using frozen diced onions, you can skip the peeling and chopping.
  2. Slice evenly. Cut fresh onions into approximately ⅛–¼-inch slices, rings, or evenly sized diced pieces. Keeping the pieces similar in size helps them dry evenly.
  3. Arrange on trays. Spread the onions in a single layer on your dehydrator trays. Use mesh liners for small diced pieces so they don't fall through.
  4. Set the temperature. Dehydrate at approximately 125–135°F (52–57°C), or follow your dehydrator manufacturer's instructions.
  5. Dry thoroughly. Onion pieces generally take 4–12 hours or longer, depending on their size, moisture content, humidity, and dehydrator performance. Rotate trays if necessary.

Doneness tip: Allow several pieces to cool before testing. Thin onion slices should be crisp and brittle, while thicker pieces should be hard and thoroughly dry throughout. If anything feels moist, soft, or flexible inside, continue dehydrating.


Fahrenheit to Celsius Converter

Move the slider to convert temperatures instantly.

135°F
95°F450°F
Celsius equivalent: 57.2°C
Fahrenheit to Celsius Converter

Move the slider to convert temperatures instantly.

135°F
95°F450°F
Celsius equivalent: 57.2°C

How to Check and Store Dehydrated Onions

Do Dehydrated Onions Need Conditioning?

Unlike dried fruits, onions should be completely dry and brittle when finished. They don't normally need the traditional 7–10-day fruit-conditioning process.

Allow your onions to cool completely, then check several pieces from different trays. Thin slices should snap or crumble, and thicker pieces should be hard and dry all the way through.

If you're unsure whether the entire batch is dry, place the cooled onions in a clean, dry glass jar for a few days and check for condensation or softening.

If you notice moisture, return the onions to the dehydrator and dry them thoroughly before storage. If you discover mold, discard the affected batch.

How to Store Dried Onions

Store completely dried onions in clean, airtight glass jars or suitable moisture-resistant food-storage containers.

Keep them in a cool, dark, dry location, away from heat, sunlight, and humidity.

For the best flavor and quality, aim to use your dried onions within approximately 6–12 months. Actual storage life depends on drying and storage conditions.

You can also grind the dried pieces into homemade onion powder using a clean spice grinder or high-speed blender. Allow the powder to settle before opening the grinder, then transfer it to an airtight container.

Storage tip: Whole dried onion pieces generally retain their aroma longer than ground onion powder. Grind smaller batches as you need them for the freshest flavor.

Dehydrated white onion pieces spread across a Nesco dehydrator tray

This very versatile veggie is great for tons of recipes: Soups and stews, you name it!

And you can grind onions up for use as onion powder!

When slicing and chopping up your onions, you might first want to invest in a good knife...


Cutluxe Chef Knife

See the Cutluxe Chef's Knife I Use

A sharp chef’s knife makes food preparation easier and gives you better control than a dull blade. I use my Cutluxe chef’s knife, which has a full-tang blade extending through the handle for strength and stability. It costs more than a basic kitchen knife, but mine has been a dependable kitchen tool when kept properly sharpened.

As an Amazon Associate, I earn from qualifying purchases—this does not affect the price you pay. Read full disclosure.

...or you may wish to treat yourself to this awesome slicer like I did:

SupMaKin Upgrade Safe Mandoline Slicer

SUPMAKIN Slicer and Dicer

The SupMaKin slicer works particularly well for producing uniform vegetable slices, although cleaning the blades and all those little grooves can be time-consuming—especially after preparing a large batch.

It's useful for slicing, but for bigger chopping jobs, I personally prefer my food processor.

You can read my full multi-function slicer review for a closer look at its advantages and drawbacks.

As an Amazon Associate, I earn from qualifying purchases—this does not affect the price you pay. Read full disclosure.

🧄 Got Extra Tray Space? Dry Garlic While You're at It

If you've got an extra dehydrator tray or two available, why not dry some garlic alongside your onions? Both enjoy similar drying temperatures, and their strong aromas won't clash the way they would with more delicate fruits.

Fresh white onion rings arranged on a Nesco dehydrator tray before drying
Dried onion rings piled in a bowl after dehydration

Reader Tip: How One Home Preserver Dried 50 Pounds of Onions

"I noticed that my white onions did not turn as brown as my Vidalia onions, did a little research, and found that it might have to do with the sweeter onion, which makes sense.

I also noticed that the Vidalia seems sweeter dried than fresh, which is fine with me.

I am so very happy that I found a great deal on them and dried close to 50 lbs of them this spring. I did do many batches outside when I saw that the humidity was very low, starting them outside in the morning.

By night the smell was almost gone when I finished them in the home."

Which Onions Dehydrate Best? Sweet, Yellow, or White?

Four different varieties of whole onions displayed together

You can dehydrate almost any type of onion, including yellow, white, red, and sweet varieties. The best choice depends on the flavor you want in your finished dried onions.

Yellow onions: A versatile everyday choice with a balanced, savory onion flavor. They're excellent for soups, stews, casseroles, and homemade onion powder.

White onions: Often have a clean, sharp onion flavor that works well in seasoning blends, sauces, and savory dishes.

Red onions: Add a slightly different flavor and attractive color to dried onion pieces. They're particularly useful when you want visible onion flakes in a recipe.

Sweet onions: Varieties such as Vidalia tend to taste milder and sweeter. Their higher sugar content can encourage more browning during drying, so keep an eye on them.

Which is best? For everyday cooking, yellow or white onions are excellent choices. If you prefer a sweeter flavor, try sweet onions. And don't forget—frozen diced onions are a convenient shortcut when you don't feel like peeling and chopping!

Whole fresh onions should be stored according to their variety and condition, generally in a cool, dry, well-ventilated location. Once dehydrated thoroughly, they take up far less space and are ready whenever you need them.

Onion FAQs: Everything You Wanted to Know About Drying Onions

Can you dehydrate minced onions?

Yes! Spread minced onions in a thin, even layer on mesh-lined dehydrator trays. Dry at approximately 125–135°F until completely dry and brittle.

Small pieces may dry faster than onion rings, so begin checking after a few hours. Drying time depends on the size of the pieces and your dehydrator.

How do you dry green onions (scallions)?

Wash the green onions thoroughly and remove any damaged portions. Slice the white and green sections into small pieces and arrange them separately on dehydrator trays.

Dry at approximately 125°F until completely dry. The thin green sections will often finish before the thicker white portions, so check them separately.

Store in airtight containers once completely cooled.

Can you dehydrate frozen onions?

Absolutely! Frozen diced onions are a convenient way to skip the peeling and chopping.

Spread the frozen pieces evenly on dehydrator trays, breaking apart any large clumps. Dry at approximately 125–135°F until thoroughly dry and brittle.

Frozen onions aren't necessarily pre-blanched, and they won't always dry faster than fresh onions. Check their actual dryness rather than relying on the clock.

Why are onions dangerous to pets?

Onions contain compounds that can damage red blood cells in dogs and cats if eaten. Fresh, cooked, dried, and powdered onions can all be harmful.

The strong smell may bother sensitive pets, but onion poisoning is primarily an ingestion hazard—not something caused simply by smelling onions.

Keep onion pieces, scraps, and powder out of reach, and make sure pets can move away from strong dehydrating odors.

What’s the best way to store dehydrated onions?

Store completely dried onions in airtight Mason jars or suitable moisture-resistant containers, such as properly sealed food vacuum-sealer bags.

Keep them in a cool, dark, dry place. For the best flavor and quality, aim to use them within approximately 6–12 months.

You can also grind dried onion pieces into homemade onion powder, although keeping them whole until needed generally helps preserve their aroma.

Dehydrated onions are a true kitchen timesaver — no more watery eyes when you want quick flavor in soups, stews, or homemade onion powder. Once you try them, you’ll wonder how you cooked without them.

If you’d like more tasty ways to use dried food, don’t miss my free 5 Dried Food Recipes That Actually Taste Great PDF below. Inside you’ll find carrot soup, minestrone, split pea soup, spicy beef jerky, and even banana cinnamon rolls—all proven favorites that make dehydrating fun and delicious!

Hand holding the 5 Dried Food Recipes That Actually Taste Great free PDF guide

5 Free Dried Food Recipes
That Actually Taste Great

Put your dried food to delicious use!
Five very different recipes.
Not one dull bite...

← Get your free copy now!

5 Free Dried Food Recipes
That Actually Taste Great

Hand holding the 5 Dried Food Recipes That Actually Taste Great free PDF guide

Put your dried food to delicious use!
Five very different recipes.
Not one dull bite...

Get your free copy now!

More From Easy Food Dehydrating

More From Easy Food Dehydrating


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Save the Harvest food dehydrating game featuring jars of dried bananas, beets, mushrooms, peas, and corn.

Test Your Food-Dehydrating
Know-How

Choose a food, make the right preparation, drying, and storage decisions—and see how many stars you can earn!

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Test Your Food-Dehydrating
Know-How

Save the Harvest food dehydrating game featuring jars of dried bananas, beets, mushrooms, peas, and corn.

Choose a food, make the right preparation, drying, and storage decisions—and see how many stars you can earn!

Play “Save the Harvest”