Storing Seeds Long Term | I Asked the Experts

Gardeners that plan ahead or grow using certain methods like to have a long-term stock of seeds available. Buying seeds in bulk is a cost-effective way to boost your seed stores. But how do you keep these seeds long-term and prevent them from going bad?

The best way to store seeds long-term is to minimize the factors contributing to seed degradation. These factors are moisture, air, light, and temperature. Vacuum sealing seeds or storing them in airtight containers and protecting them from heat, light and moisture extends their viability.

Several circumstances reduce seed viability after long-term storage. Storing your seeds in the correct container and the right environment preserves the seeds for longer and increases the germination rate even after many years of storage.

How To Store Seeds Long Term

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Growing microgreens requires a constant supply of quality seeds to transform into this nutritious food source. Microgreen growing is one reason gardeners order seeds in bulk, but other growers stock up on seeds to provide seed security for years to come.

Whatever your reason for long-term seed storage, you must find a way to store your seeds correctly to ensure their viability in years to come.

Pro tip: If prepping is your big motivation for storing seeds long term, I recommend sprouting as one of the best options. I personally recommend this Handy Pantry Food Storage Sprouting Kit if you want to store sprouting seeds long term. If you are interested in storing “regular” vegetable seeds long term, I recommend Storage Seeds in a Can.

Why Seeds Go Bad

Understanding why seeds go bad and what affects their long-term germination rate helps us package and store the seeds correctly. This boosts our success rate for preserving seeds long term.

Seeds can go bad for several reasons and understanding the main factors that influence seed germination rates is key to developing our seed storage strategy.

Four main factors contribute to seeds losing viability over time.

Oxidization. Seeds oxidize over time in the presence of oxygen. The presence of oxygen degrades the DNA in the seed, which negatively affects the seed’s germination and can create weak plants even if the seed germinates.
Moisture. Moisture is present in all new seeds since nature intends for the seeds to grow within a year. Moisture in seeds stored long-term can result in the development of mold, which reduces seed viability.
Heat. Warmer temperatures are a natural trigger for seeds to start germination, and the seeds never become completely dormant at higher temperatures.
Light. Light stimulates the germination process in seeds, especially when combined with heat and the presence of moisture.

Understanding these factors allows us to adjust our seed-storing techniques to produce a better germination rate after storing the seeds for many years.

How Long Seeds Last

The time that seeds remain viable varies from seed type to seed type. Some seeds can remain viable without special storage for 1 to 2 years, while others can remain viable for up to 5 years.

Onions, parsnip, and peppers seeds have short natural viability, while beans, peas, and corn are seeds with longer natural storage potential.

We can increase the duration we can store seeds by taking steps to eliminate as many factors contributing to the seeds going bad as possible. This mostly involves using the right packaging and storage location to keep our seeds.

The packaging used to package the seeds affects the long-term storage of the seeds depending on how many of the negative factors the packaging eliminates,

Check out the top Indoor Gardening Resources personally recommended by Stocking My Pantry

Best Seed Storage Containers for Long-Term Storage

The best seed containers for long-term storage are the ones that reduce the factors that contribute to seeds going bad.

Small seed quantities are often supplied in paper packets, which are not good for long-term storage. The paper packet reduces light but does not control moisture, air, or heat affecting the seeds.

Seeds supplied in paper packets usually have a “best before” date stamped on the packaging. These seeds are typically only good for a year unless you package them differently.

Pro tip: If you’re interested in storing seed packets long term, put several seed packets in a mason jar, and vacuum seal them. To do so, you’ll need a vacuum sealer and mason jar attachments, all available on Amazon.

Storing Seeds in Mylar Bags

Mylar bags are better for seed storage than paper packets. The mylar reduces light access, air, moisture, and, to some extent, heat.

Seeds packaged in mylar bags will last longer than seeds in paper packets, but there is still more you can do to further extend the life of your seeds.

Pro tip: To learn more about how to use mylar bags for food storage, check out my article, Long Term Food Storage in Mylar Bags. While it’s specific to storing food, the same tips apply to using mylar bags for storing seeds.

Should You Vacuum Seal Seeds for Long-Term Storage?

Vacuum sealing is a good way to store seeds and will extend their viability. The vacuum packaging removes air to prevent oxidization and removes moisture from the seeds to prevent mold.

Vacuum sealing cannot be done on paper packets, but mylar bags and mason jars work well for this option, and vacuum sealing adds another level of protection.

Pro tip: Check out this selection of vacuum sealers on Amazon. If you’re going to vacuum seal your seeds in mason jars like I do, you’ll need an attachment for your vacuum sealer like these, found on Amazon.

I buy seeds in bulk, usually in 5-pound sealed canisters. There is generally no “best before” date on these containers to guide you on the expected duration of the seed viability.

Once you open the bulk container to use some seeds, what do you do to preserve the remaining seeds? The seeds come in large containers depicted below, and it is not possible to reseal them adequately to preserve the seeds long term

#10 cans of sprouting seeds work well for storing seeds long term.

I vacuum seal the remaining seeds from the bulk containers in glass mason jars. Mason jars make excellent long-term seed storage containers! The sealing process removes the air and moisture; all that remains is storing the mason jars in a cool, dark location.

This is what the seeds look like after they have been sealed in the mason jars. I label each jar with the type of seed, the date the seeds were purchased, and the supplier I used to source the seeds.

The date the seeds were purchased is more an indication for me which seeds to use first rather than an “expiry date” for the seeds. Always use your oldest seeds first to ensure the seeds in your long-term storage are as fresh as possible.

Not Everyone Agrees About Vacuum Sealing Seeds

I do want to say that not everyone agrees that vacuum sealing seeds works well. Some claim that seeds die with lack of oxygen. However, I’ve always vacuum sealed the seeds I buy in bulk and they’ve done well.

I reached out to Gil, of Sproutpeople.org about this, and here’s his response.

email from SproutPeople about whether or not you should vacuum seeds for long term storage.

From his response you can see that he doesn’t have personal experience with vacuum sealing seeds, but does receive vacuum sealed seeds from big suppliers. The fact that big seed suppliers vacuum seal seeds, coupled with my own personal experience with vacuum sealing seeds gives me the confidence I need to continue vacuum sealing microgreen seeds that I buy in bulk.

Pro tip: I purchase all of my sprout and microgreen seeds from True Leaf Market. I’ve been a customer for more than four years, and always had a great experience. Overall, I’ve found their products to be great quality, at good prices. I did have a problem with one order and they immediately made it right. You can see their full selection of seeds and supplies here.

Check out our Microgreens at True Leaf Market

Best Environment for Long-Term Seed Storage

The best environment to store seeds long-term reduces the factors that cause seeds to spoil. The following guidelines will help you locate the best place in your home to preserve your seeds for the longest time.

Airtight. This refers to the container used to store the seeds.
Dry. The environment must be dry to prevent moisture contamination of the seeds. Humid locations are not good seed storage locations.
Dark. Limiting the seeds’ light exposure will extend their storage life.
Cool. A location with a constant cool temperature is ideal for encouraging the seeds to enter a dormant state and increase their storage life. The cooler the location, the better.
Rodent-proof. To ensure you are not storing food for local rodents, make sure your containers and storage location for your seeds are rodent-proof.

Pro tip: Amber-colored mason jars, like these from Amazon are a great option. You can vacuum seal them, they are rodent-proof, and the amber color blocks out light.

Should You Store Seeds in the Freezer?

Storing seeds in the refrigerator is a good idea to lower the storage temperature of the seeds, but it becomes impractical if you have a large volume of seeds.

Freezing seeds is another good option, but it should only be done if the seeds have no moisture. Freezing seeds with moisture can damage the seeds as the moisture expands during the freezing process.

Store the seeds with a desiccant in the packaging for up to 3 days before placing them in the freezer to avoid damaging the seeds.

Freezer and fridge space may not be options for you if you have large volumes of seeds. If this is your situation, then using the 100 rule will help you store your seeds for longer.

The 100 rule is a combination of the humidity and temperature in Fahrenheit in the location where you store your seeds. The sum of the temperature and humidity must not total more than 100.

For example, if the humidity is 25% and the air temperature is 60°F, the total is 85. This value is below the 100 limit and would be a suitable storage location for your seeds. This location can be a pantry, a kitchen cupboard, a closet, or even a basement if there is not too much humidity.

Check out the top Indoor Gardening Resources personally recommended by Stocking My Pantry

Best Seeds for Long-Term Storage

Different seeds have varying natural viability durations, but packaging and storing any seed correctly can extend the time the seed can be stored and remain viable.

Parsnips, most herbs, and all allium family seeds, such as onions, do not have a robust coating on the seed, which makes them more susceptible to damage in long-term storage. The seed viability can be reduced by as much as 50% each year of storage.

Packaging the seeds as we have described will extend their viability to 3 or 4 years, but they should be cycled as soon as possible.

Beans, peas, corn, or maize seeds can last more than 100 years if they are stored correctly. The best option for your seed storage is to date your seed containers and use the oldest seeds first to ensure the best germination results.

Conclusion

Long-term seed storage makes a lot of sense for most gardeners, especially if you grow microgreens or want to save seeds from your own plants. It is possible to extend the natural viability of seeds by storing them in the correct container and locations with the right conditions.

Following the guidelines I have described will extend the time you can successfully store your seeds long-term.