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Can you Freeze Seeds? Here’s how to make them last longer

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Seeds are becoming ever important to ensure high producing and productive varieties of vegetables are maintained and freezing is a viable option in doing so.

Seeds of vegetables, fruits, or flowers are the base of the growing process, and having the right variety of that particular plant or vegetable can ensure you get the same great result every time.

Seeds can be frozen by placing them into a sealed container from which the moisture has been removed. Humidity shortens the lifespan and viability of seeds as it promotes bacterial activity. Seeds can last a long time by reducing humidity and keeping it in sealed containers within the confines of a refrigerator.

In this article, we would explain how you can freeze seeds, the things to look for to ensure it is done properly, along with some need-to-know facts.

Can Seeds be Frozen?

Freezing Seeds before planting (1)

Improper storage will cause seeds to develop mold and go bad over time.

For every 1% increase in humidity, a seed can lose half of its storage life. Likewise, every 10-degree Fahrenheit increase in temperature can also cost seeds half their storage life.

Freezing seeds fairly easily as it does not cause any damage.

The life span of the seeds can be significantly lengthened by lowering the atmospheric temperature around them.

This slows the biological organisms, mainly bacteria, from causing damage (rot) to the dermis (coating) of the seed

When bacteria are allowed to thrive and have already established a white fuzzy appearance will be seen covering the out parts of the seeds.

Environmental conditions such as temperature and humidity have to be effectively controlled to ensure the seeds do not rot.

Ambient air contains water. The amount of water contained in the air is a measure of its humidity. The leaving seeds exposed to ambient conditions will surely damage them over time.

How to Freeze Seeds?

How to freeze seeds

One of the factors that affect the preservation rate of the seeds is the method of their storage. 

Because plants are available in different sizes and forms so the seeds also come in different sizes, forms, and shapes. 

The secret to a very successful seed storage method is “Cool and Dry”. As early as the seeds come, you have to store them immediately and keep the following things in mind:

Using ZipLoc Bags to Freeze Seeds

Ziploc bags are very cost-effective and efficient when it comes to storing seeds. There are many options to choose from but we recommend those bags that can be sealed with a vacuum sealer.

Vacuuming the inside of the bag essentially removes the moisture within the bag removing any chance for bacteria or even frost from forming when the seeds are frozen.

Sealed Plastic Containers To freeze Seeds

Similar to ziploc bags, plastic containers are another great option for storing seeds because they can be stacked and labeled so organizing can be daily easy. 

This is an advantage over the zip loc bags as the bags tend to get mixed up and lost when they are packed in the freezer with other items.

Some plastic containers come with an option to vacuum seal just like the bags and give the added benefit of moisture removal for proper and effective storage.

We do recommend going for vacuumed plastic kits as they are the better option to ensure seeds are stored properly for a long period of time.

Factors to Take into Consideration when Storing Seeds

Temperature

The temperature of the surroundings matters a lot. Set the Temperature as 20- 24 degrees centigrade (70-74 degrees Fahrenheit).

Humidity

Humidity

The maximum germination percentage was observed in seeds with a low percentage of water. The lower the moisture content, the more the life duration of the seeds will be. 

The maximum time limit that has been observed in seed germination is 90 days. 

After 90 days the seeds’ life will begin to decline, it doesn’t matter how moderate the temperature is and how friendly the environment is.

Will Seeds Germinate After Freezing?

Seed Germination

There is a time limit after which every seed will germinate even though how suitable the environment is or how moderate the temperature is or how much effort you did for its preservation. 

It will germinate after a fixed time. The fixed time duration is 90-100 days. The maximum germination percentage was observed in seeds with a low percentage of water. 

At low humidity levels, the more the life duration of the seeds will be, and the maximum time limit that has been observed in seeds germination is 90 days. 

There is a time limit after which every seed will germinate even though how suitable the environment is or how moderate the temperature is or how much effort you did for its preservation.

If seeds are harvested, it is essential that they are dried before storage. This helps prolongs the life of the seed by quickly drying out the outer protective layer.

See our detailed article on how to dry seeds

Drying Seeds Before Planting

How to Thaw Out Seeds for Planting?

This is the most important step of the process. So, you have to take great care. Because it is the step where you are going to get the reward of all your previous hard work.

Procedure for Thawing Seeds –

  1. Place an absorbent material (paper towel) on a flat surface
  2. Remove the container with seeds from the refrigerator and place it on the absorbent material at room temperature.
  3. Allow thawing until no more condensation is seen. Wipe dry if necessary.
  4. When no more moisture is seen (properly thawed), Open the lid of the container.
  5. Remove the seeds
  6. Place the seeds onto another paper towel. This prevents moisture from settling on the seeds before planting.
  7. Plant or Sow as soon as possible.
Drying Seeds after freezing

Seed Storage Facts

  • High humidity lessens the storage time of seeds.
  • A 1% reduction in the seed moisture, seed life will double.
  • The germination rate depends on the age of the seed
  • Germination depends on the stage at which it was harvested.
  • A dry place is more suitable than a cool place.
  • Some seeds will remain viable in storage for several years if stored under optimal conditions — namely, low humidity and low temperature (42°F or 5.6°C).
TypeAvg Storage Life (Yrs)TypeAvg Storage Life (Yrs)
Artichoke & Cardoon1–4Fennel3–4
Arugula6Kale3–5
Asian Greens3Kohlrabi3–5
Asparagus3–4Leeks2–3
Beans2–4Lentil1–2
Beets2–5Lettuce1–6
Broccoli3–5Melon3–6
Brussels Sprouts3–5Mustard4
Cabbage3–5Okra2–3
Cabbage, Chinese3–5Onions1–2
Carrots3–4Parsnip1–3
Cauliflower4–5Peas2–4
Celery & Celeriac3–5Peppers2–5
Chicory4–5Pumpkins4–6
Collards3–5Purslane3–5
Corn, Sweet1–3Radish4–5
Cress5Rutabaga3–5
Cucumber3–6Salsify1–2
Dandelion1–2Soybean3–5
Eggplant4–5Spinach1–5
Endive5Squash & Gourds3–6
Turnip4–5Swiss Chard2–5
Watermelon4–5Tomato3–7
Source

The Best Places For The Storage Of Seeds

Storing seeds safe can be done without freezing but the lifespan will be less than that of freezing.

How in both cases, storing seeds (feezing and without freezing) the humidity must be as low as possible because moisture promotes biological activity causing bacteria to feed on the seeds.

In the Basement

Basements are the places where there is fairly large humidity. Moisture from the walls of the basement can enter the air. 

If you feel less or more humidity in your basement then it will surely not be a suitable place to keep your seeds.

Closets

The main floor of your home is drier than your basement. So, you have to put your seed in a dry place as compared to a cold place because DRY is more important than COOL. 

Because the sun is much more direct to the first floor as compared to the basement the weather conditions on the first floor will be more comfortable and convenient.

Does Freezing Ruin Seeds?

Seeds are the keys to the propagation of plant life through periods of drought or any kind of famine. Improper freezing can kill some seed’s life. 

But other seeds may be less fussy. In summer the increase in temperature will trigger the seeds. The change in the environmental conditions affects the seed life.

Seeds that can be Frozen?

Orthodox seeds have the capability to dry up internally and keep their moisture at 12%. Recalcitrant seeds are not suitable to store in a normal freezer because they can’t survive at 20 degrees centigrade. 

Freezing will greatly improve their lifespan.  You can easily store SUNFLOWER seeds in moderate freezers. You also can store TOMATOES seeds at 32–41-degree Fahrenheit. 

Tomato seeds are sensitive. 

So, we have to be very careful about it. Tomato seeds required very very less moisture and an airtight bag to store is. 

You can also store PUMPKIN seeds at moderate temperature. You can also store vegetable seeds, fruit seeds, and other green plant seeds for further use.

How Long can Seeds be Kept Frozen before Planting?

There is a time limit after which every seed will germinate regardless of the fact that how suitable the environment is or how moderate the temperature is or how much effort you did for its preservation. 

The fixed time duration is 90-100 days.

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