I confess. I am a saver of leftover seeds. On occasion I’ve saved packets for years then wondered if they would be any good. When I first started gardening, I used to just take a chance, but after having to replant beans, carrots and lettuce one year, I figured I’d better learn something about how long seeds can be stored before they lose their viability.
As seed ages, the likelihood that it will germinate decreases even if stored properly. In general, longer seed storage life happens when seeds are kept dry and in cool temperatures. Most seed packets have a date on them indicating when they were packed. Gardeners who save seeds from open-pollinated plants should be sure to include a harvest date on the seed label.
There are compact tables that tell the longevity of well-stored vegetable seeds but the tables for flower seeds are huge! A fairly simple germination test will help determine whether saved flower seeds will produce the number of plants you want.
Here’s what is needed for a germination test: paper towels or napkins, a plastic bag or plastic wrap, a mister bottle and the seeds.
Count out a number of seeds. If you have only a few seeds from a special plant, use 5 seeds, or use 10 to 20 if you have lots of seeds. Moisten a paper towel or napkin with the mister bottle then place the seeds neatly on the towel and fold or carefully roll the paper towel so the seeds stay separated from each other. Gently place the moistened towel with the seeds into a plastic bag or in some plastic wrap. Label with the date and seed variety, then place it in a warm area (70 to 80 degrees). Check seeds in two or three days and every day after that until germination takes place. When a root protrudes through the seed coat, the seed has germinated. After the first seeds have sprouted, check daily for a week until no more seeds have sprouted. You can calculate the rate of germination by dividing the number of seeds germinated by the number of seeds tested. If the rate of germination is quite low, you may want to reconsider using the seeds or seed heavily to make up for probable poor germination. The sprouted seeds can, if carefully handled, be planted in the garden (if the planting time is right) or in peat pots or cell packs for further growth.
This same process can be used to learn about germination rates for plants you are not familiar with. It will help to determine how early you should start the seeds.
Viability of common vegetable seeds is easier to chart. Keep in mind that there are always exceptions. Short-lived seeds such as corn, leek, onion, and parsnip generally store for one year. Beans, carrot, celery, chard, eggplant, parsley, peas, pumpkin, and squash will most often be viable for up to three years. Longer-lived seeds, up to five years and possibly more, include beets, broccoli, Brussels sprouts, cauliflower, cabbage, collards, kohlrabi, cucumber, kale, lettuce, melons, peppers, radish, rutabaga, tomato and turnip.
Store saved seeds in a cool, dry place, even in tightly closed jars in the refrigerator. If in doubt about using them, try a germination test.
This column is a volunteer service of the Beltrami County Master Gardener Writers’ Group. For more information on gardens in Minnesota check on-line for locations, addresses and directions. Look for information about horticulture on the University of Minnesota Extension Home and Garden Information page www.extension.umn.edu/gardeninfo or on the Beltrami Master Gardener site beltramicountymastergardeners.org.
