storing seeds for next year
temperature. Just make sure your seeds are thoroughly air dried, pack all your packets in an airtight container on a dry day, and store in a cool place where the temperature doesn’t change much. A nice cool stable temperature is best. The following table of the usable life of seeds is based on this seed storage method.
Note that airtight does not include Ziplock type bags. Airtight would include glass jars with canning lids with rubber seals.
Professional long-term storage of seeds with little germination and vigor loss can be obtained easily as well! Although the method described above is sufficient for most seeds and for shorter time periods such as years, the ideal for long term storage is -8% seed moisture and freezing temperatures. Seeds stored frozen like this can keep viability and vigor 10 times longer than normal! The low 8% moisture is necessary before freezing, as moisture content higher than this will damage the seeds when frozen. The excess moisture when frozen will expand and burst and damage cells in the seeds.
To dry seeds to approximately 8% moisture, all you need is color changing silica gel, cloth bags or paper packets, and a large airtight glass jar with an airtight lid with rubber seal, such as a canning jar and lid. The silica gel comes as blue colored beads. Put your seeds which are already at room dryness into labeled paper envelopes or cloth bags. Take enough packets that will fill the jar half way and weigh them. Then put into the jar. Only fill the jar half-way with seed packets to leave room for the silica beads. You can use a large jar and dry several packets of seeds at once. Next measure out an equal weight of silica beads in the jar with the seeds. Close the jar tightly.
Leave the seeds out of sunlight for seven to eight days. At this point most large seeds will be about 6-8% moisture and small seeds could be as low as 4% to 5%. Special care should be taken not go any longer or lower in moisture than this, as dormancy problems could occur.
After the seven to eight days, its time to remove the silica gel. The seed packets should be transferred to another airtight jar and sealed as quickly as possible as they will start re-absorbing moisture from the air right away. Store your jar of seeds in a standard freezer which is usually set at 0°F. They can also be kept in the refrigerator but freezing is best.
When opening a jar of frozen seeds, the jar must be allowed to warm up to room temperature first to avoid moisture condensation on the super dry seeds. So allow to sit several hours to overnight.
Try to open the jar as infrequently and for as little time as possible. The more often the temperature fluctuates the shorter your seed life will be.
Allow the seeds to sit out a day or so to reabsorb some moisture before planting if at all possible.
The silica gel beads can be reused forever by drying in the oven or microwave until their dark blue color returns. Dry on a cookie sheet in a 200°F oven for several hours. Or a microwave for about 20 min. Watch closely so they don’t burn and become unusable. Once dry, store in an airtight container.
And that’s it! Never let those extras seeds go to waste again!
©Melissa Hilsgen 2014