Long Term Seed Storage

When it comes to gardening, having a good supply of quality seeds is essential. However, not all seeds will be used immediately after purchase, and you may also need to keep a vault of survival seeds in long term storage for future use, so keeping your seeds fresh and viable for extended periods is vital. While a seed’s viability and germination rate will generally decline to some extent over time, there are several long term storage practices that will ensure your seeds will be viable and produce healthy harvests, many years down the road.

Proper long term seed storage involves storing seeds in a stable environment that allows them to remain in an uninterrupted dormant state. To achieve this, there are 3 main environmental conditions that need to be controlled: MOISTURE, LIGHT, and HEAT. Each of these elements can spur a seed to sprout or decay, so it’s important to store your seeds in a dark, cool place (preferably without too much temperature fluctuation) and in an airtight container that protects them from moisture.

There are several different methods to achieve this, and while there is not a total consensus among growers on the absolute, perfect storage method, there are several best practices that will achieve good results.

MOISTURE / STORAGE CONTAINERS

Because water is essential for the sprouting process, it is important to keep your seeds well-protected from moisture / humidity. Plastic containers, Mason jars, and other glass containers are excellent for seed storage, provided they are sealable. Paper envelopes for seed organization need extra care to keep them dry, while plastic bags should be checked for moisture and air removal before sealing. Condensation can occur in cold environments optimal for seed dormancy, so using silica gel packets can help control excess moisture and protect seeds against decay.

STORAGE TEMPERATURE

Different temperatures cue different seeds to germinate, so storing your seeds at a consistent 40 degrees Fahrenheit or lower is optimal. This is why many growers store seeds in their refrigerator or freezer.

So which option is better - refrigerator or freezer?  If you're just storing seeds for a few seasons, refrigerator storage is a solid option and is preferred by many growers. if your goal is to store seeds for 10, 15 years or longer, freezing seeds is the best option to keep them in a constant dormant state, as long as seeds are dry before freezing and you don’t let them thaw more than once. There are seed banks around the world that store seeds frozen, and in Norway there is even a global “doomsday vault” with seeds from almost every country, stored at 0 F.

One important note on freezer storage - when removing seeds from the freezer, it’s important to let them reach room temperature before opening the sealed containers, in order to avoid moisture damage. Also, if you want to ensure that your seeds are dry enough prior to freezing, you can test them with the bend test. If it snaps or breaks easily, it is dry. If it bends or mushes, it’s not dry enough. In that case you can air them out with a fan and try again the next day. (With small seeds, you can use tweezers to do the bend test).

If you can't store your seeds in the refrigerator or freezer, store them in sealed containers in a cool, dark room or closet that maintains a fairly consistent temperature. Even stored in this manner at room temperature, many seeds will maintain great germination rates for 3-5 years.

STORE SEEDS IN THE DARK

Light is another cue for seeds to sprout, so storing seeds in dark and dry places is essential. Transparent containers should be kept inside opaque containers, cabinets, or beneath other things that block out light. Sunlight should be avoided as the rays can damage seeds and decrease germination rates.

By following these best practices, you can ensure the viability of your stored heirloom seeds, long into the future.