How To Freeze Dry Green Onion

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Freeze Dried Herbs & Spices

Green Onion is such a versatile herb. You can use it in soups, bread, crackers, dips; you name it. If you’re blessed with a garden, you can have a good harvest during the summer. They’re so easy to grow and give you such an abundant harvest that it’s easy to end up having more than enough. Or when it’s in season, you get such great deals on a bunch or two. Unfortunately, it can only last for 2-3 weeks in the fridge. 4-5 if you’re lucky. So, here’s how to freeze dry green onion so you’ll have a good supply to last you for 25-30 years.

How Do I Choose Green Onion For Freeze-Drying?

It’s easier to pick green onions that are fresh from your garden. You can see that vibrant green color with the firm stalks. The challenge is getting the best ones from the grocery store.

Check for Roots

When choosing green onion, inspect the bottom part first. There should be roots attached to each stalk. Some have long roots; some have short roots. The length doesn’t matter. What matters is that you see roots at the end of the aromatic. Why are the roots important? The roots are what preserve the green onion’s freshness. Those without roots may look cleaner and more presentable. However, it won’t keep long, and the flavor will be lacking.

Choose Firm Ones

Firmness is a good indication of how fresh a green onion is. A firm, crisp white bottom means your aromatic has all that oniony flavor that you need. If the bottom end is soft and squishy, you got a stale green onion in your hand.

The stalks should also have a consistency like a thin, plastic drinking straw. They should be able to stand upright without support. Some may naturally curve downward, that’s fine. What you don’t want are stalks that are soft or floppy. Occasionally you’ll get 2-3 deflated ones, so that’s okay. You can easily discard them because you still have lots of fresh ones. But if you got almost a fourth of the bunch that is wilted, discard that bunch.

Go for A Vibrant Green Color

The top ends should be a vibrant green coloring as the leaves emerge from the bulb to the top. The color should be even, with no yellowing, browning, or fading. If any stalks appear discolored, take them out and choose better ones.

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How Do I Prepare the Green Onion for Freeze Drying

Have you chosen your bunch of green onion? Good! It’s simple to prepare your aromatic, depending on how you want to use it.


It’s very important that you wash green onion. Whether you harvested it in your garden or bought it from the store, cleanliness is a must. Especially with this one. The roots may retain freshness, but they also hold soil and dirt. Wash each stalk carefully, making sure that all the soil is out.

You can soak your aromatic in water for a minute to soften the debris. Then wash it under running water, going in between the leaves. This will ensure that you get all the dirt out and have clean food for processing.


How do you intend to use your aromatic? Is it for garnishing, to add flavor to soups, bake with it, or make omelets? How you’ll use it will determine how you will prepare it.

For garnishing and adding to soups, you can mince them or slice them thinly. You can also leave them whole if you want. Some people make awesome omelets with full stalks of green onion.

Do I Pre-Freeze?

Since we’re dealing with an aromatic herb, pre-freezing is optional. It can certainly help shorten the process by removing some freezing time. Harvest Right recommends that if you pre-freeze, do it for at least 48 hours. This way, you get good solid crystals throughout the material.

If you do decide to pre-freeze, make sure to do the same thing with your freeze-dryer trays. Warm trays will also lead to condensation, affecting the final product.

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How To Freeze Dry Green Onion

We’ll do two versions on how to freeze dry green onion. One is for those with a software lower than v5.x.19, and the other for v5.x.19 and higher.

For Lower Versions

  1. Turn on your machine and press “START > NON-LIQUID”
  2. If you pre-froze your food, choose “PRE-FROZEN”. If not, choose “NOT FROZEN.” Remember not to mix frozen and non-frozen trays.
  3. Wait for the machine to pre-freeze for 15-30 minutes.
  4. When the machine is ready, it will tell you to load the trays in the freeze-dryer. Remember to close the drain valve.
  5. Seal the freeze dryer door and press “CONTINUE”
  6. Let the machine do its work.

For Higher Versions

  1. Turn on the machine and “START”.
  2. Wait for the chamber to cool down for 15-30 minutes or until it reaches your initial freeze temperature.
  3. Once it’s ready, it will tell you to close the drain valve and load the trays.
  4. Close the chamber door, ensuring that there’s a tight seal around the ring.
  5. Press “CONTINUE” and wait for the machine to finish its work.

The newer version no longer asks you if you pre-froze your food. The sensors automatically determine the state of the food and process accordingly.

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How Long Does It Take To Freeze-Dry Green Onion?

Since we’re dealing with a leafy aromatic, the process doesn’t take a lot of time. Freeze-drying green onion will be about 16-24 hours depending on:

  • Temperature and humidity of the room where you installed your freeze dryer.
  • The vacuum pump you use.
  • How much food you’re freeze drying.
  • Structure of the food you’re freeze drying.
  • Age and software of the machine.

Some say that the new software version is faster than the old one. On the other hand, some say that the older version is more reliable than the new version.

How Do I Rehydrate Freeze-Dried Green Onion?

Rehydrating is very simple. You could do either of these options.

  • Pack the freeze-dried green onion delicately in a wet paper towel. Then place it inside a sealed container or a Zip Lock bag for 15-30 minutes.
  • Put the herb in a bowl with enough water that pools at the bottom. After several seconds, mix the freeze-dried green onion so that every piece has moisture. Let it stand for 5 minutes.
  • Lay the freeze-dried aromatic on a single flat layer on a plate. Gently spritz with water and let it stand for 5 minutes.

If you’re using freeze-dried green onion in soups and sauces, there’s no need to rehydrate. Just add a bit more water if needed because it will soak up moisture.

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How Do I Store It?

Storing freeze-dried green onion is easy. If you use it often, you can put it in a Mason jar. They’re easy to open and seal whenever you need them. If you plan to store it long-term or bring it with you on trips, Mylar bags will work awesomely. They’re compact, lightweight, and designed to keep your freeze-dried aromatic for decades.

Before you seal your chosen container, remember to put in oxygen absorbers. 1-2 of the 300cc packets are good for every gallon size of your container. These take out residual oxygen inside your bag and help extend shelf-life.

After sealing, keep your containers in a cool, dry, dark place. Your storage temperature should be lower than 72°F (22 °C). Relative humidity should also be 15% or less.


Freeze drying green onion is the best way to keep your herb for a long time. They get this amazing crunch that enhances the texture of your food. The flavor also intensifies in its dried state. When you rehydrate it, it’s almost impossible to tell it if it’s freeze-dried or fresh.

Will you use harvested or store-bought green onions to freeze dry? Let us know in the comment section.

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