How to Store Seeds
If you garden, you’re going to end up with extra seed or seed that you save. The question then becomes what is the best way to store them to maintain the most viability until they are planted? Cool, dry, and dark describes the kind of environment that seeds will store the best in. We are trying to create a stasis type of environment. Basically we are trying to create the opposite environment for what seeds need to germinate, which is moisture, light, and warm temperatures.
Temperature- Ideally the temperature is low and constant, not fluctuating. This is why many people store their seeds in basements, because the cool underground temperatures remain relatively constant.
Humidity- Moisture is not your friend. I repeat moisture is not your friend. Low humidity is more important than low temperature. A low humidity can be maintained by storing your seeds in air tight containers. Air tight glass jars are a good option. I use very good freezer zip lock bags to store batches of seeds that I use together. I then put all zip lock bags into a food grade bucket with a gamma seal lid that keeps the entire bucket air tight. This allows me to open the bucket without allowing air to get to all my seeds every time I need seed. Then I can just open the zip lock bag of the seed I am looking for. It is important to neatly label the zip lock bags with what seed is contained inside. Suzanne Ashworth, who wrote a great seed saving reference book called “Seed to Seed”, does not think zip lock bags are air tight, but I can’t get air out of them when they are sealed, so we will have to disagree there. She prefers glass jars. I like glass jars as well, but they are more expensive, and you can’t tell if something is wrong with your lid, and the jar is not air tight.
The other very important concept to understand, especially if you are saving your own seed is the seed must be sufficiently dry before putting into storage. Seeds like pepper and tomatoes should break when you try to bend them, and bean and corn seed should shatter if you take a hammer to them. I like to dry my seed in my greenhouse in the late summer. I just cut the whole plants down and hang them upside down. My greenhouse is so hot and dry in the summer that it is like an enormous solar dehydrator. Another option is to use a food dehydrator, or place the seed in an air tight container with a silica gel packet for a week before transferring the seed to its resting place. Don’t leave the seed in with a silica gel packet forever though, as it can get too dry.
Light- Seeds should be stored in a dark place out of any light, especially sunlight. This is pretty easy to do, as seeds can be stored in containers that keep light out very easily.
Refrigeration- Seeds can be refrigerated, and it is a decent option for longer term storage. Make sure you have air tight containers. I would not refrigerate seed if you are planning to use it within a couple of years, especially if you need to get into the container often, as the large temperature fluctuation is not good. Also, you have the other negative of giving up fridge space, and if you have a power outage, the seeds are experiencing that temperature fluctuation again.
Freezing- I do actually have an airtight, dark, container filled with mylar packed seeds. These are seeds that I am storing for the long term, and the freezer has a backup power supply. These are seeds that I can use in an emergency. I would not however store the bulk of my seeds this way, or any seed you plan to use within three seasons.
Conclusion- Store your seeds in a cool, dark, dry place where the environment does not change much. For me that is, in my basement stored first in paper envelopes, then the paper envelopes go into air tight zip lock bags, then into my food grade bucket that is sealed air tight with a gamma seal.