How Long Garden Seeds Last in Storage
Consult three different charts on how long garden seeds last in storage and you will find three different sets of answers. That’s because the longevity of stored seed has not been definitively determined. Too much depends on variables that include cultivar, growing conditions, harvest conditions, and of course, seed storage environment. We gardeners don’t have full control over the first three variables, but we do have guidelines for maximizing the longevity of stored garden seeds.
Storing Garden Seed
Once garden seeds have been prepared for storage, they should be placed in well-sealed containers. I try to use the smallest possible container for each type of seed, to minimize air space.
After washing a vial or jar for reuse, make sure it is fully dry before putting in the seeds. One season I lost a whole batch of lettuce seeds when they sprouted, and then died, inside a still-moist vial.
The secret, if you could call it that, to storing seeds is to keep them cool and dry. If your storage conditions are less than ideal, dry is more important than cool. As a general rule, try to find a place where the temperature plus relative humidity add up to less than 100.
We store our sealed seeds in the basement. They are organized by category in small plastic storage boxes with snap lids. To keep out humidity, we place a reusable silica gel pack in each box. The following table indicates how long we expect each type of garden seed to preserve well in storage.
| Years | Seeds |
| 1 | chives, edemame, leek, mache, marjoram, onion, parsley, parsnip, rosemary, salsify, savory |
| 2 | corn, okra, pepper, sage |
| 3 | arugula, bean, broccoli, carrot, celeriac, celery, napa, pea, radicchio, shallot, spinach, thyme |
| 4 | beet, Brussels sprouts, cabbage, cauliflower, chard, chicory, eggplant, fennel, kale, kohlrabi, mustard, pumpkin, rutabaga, sorrel, squash, tomato, watermelon |
| 5 | artichoke, basil, cantaloupe, claytonia, collards, cress, cucumber, dill, endive, escarole, lettuce, mache, muskmelon, radish, turnip |
The number of years doesn’t mean the seeds suddenly become non viable. Rather, the years indicate the amount of time by which germination rate has dropped to 50%. By that time you need to sow at least twice as many seeds to get the same number of plants that would grow from fresh seed. Instead of tossing out seeds that pass their prime, you can test the seeds for germination rate.
Storing Seed in the Freezer
We don’t have enough freezer space to store all our seeds. But one of our neighbors stores his seeds in zipper snack bags in his freezer. He has viable seeds in his freezer that his grandfather gave him four decades ago. He also saves seeds from his own garden. But he always keeps some of his grandpa’s seeds in reserve, “just in case.”
Storing seeds in the freezer not only keeps them viable longer, it also destroys any insects or insect eggs that might be present. Seeds to be stored in the freezer must be absolutely dry, so they won’t burst when frozen. And the freezer should not be self defrosting, which alternately thaws and refreezes — not a good environment for seeds.
Get Started
If you haven’t yet started saving your own garden seeds, an excellent resource is The Seed Garden, a comprehensive species-by-species seed harvesting and storage guide for 75 common vegetables and grains. Another good resource is The Organic Seed Alliance’s 30-page Seed Saving Guide you can download for free.
