How to Test Seed Viability
How to Tell if Old Seeds Are Viable if Leftover or Old Saved Seed Will Still Germinate Sprout and Grow When Planted
Dec 26, 2006
If you are a seed saver and saved your own flower or vegetable garden seeds from last year (see Seed Saving Information Directions and Tips) or if you have left over seeds from last year or the year before, are the seeds still any good? Will the seeds germinate and grow? Are the seeds viable? The answer is maybe yes, maybe no. Seeds might seem like inanimate objects, but in reality they are alive. Some seeds are naturally very short lived (sweet peas and delphinium for example) while other seeds may easily retain viability for several years and maybe for as long as a decade. Storage conditions affect the longevity of seeds as well. You can do an easy germination test at home to check on seed viability and seed germination rate.
Do A Germination Test Before Planting Old Seeds
If you have some leftover or older seeds and wonder whether or not they are viable and will still germinate and grow, you can find out for sure with a germination test. It’s better to test your seeds before planting than to waste time and effort planting seed that is no longer viable – and why purchase more seeds if those you already have are still good?
How to Set Up Easy Seed Germination Test
Take a small sample of your seeds to test, maybe ten seeds or so from each batch. Slightly dampen a paper towel and place the sample seeds on it. Fold the barely damp paper towel it in half over the seeds. Enclose in plastic wrap or place inside a sealed plastic bag so it will stay damp. Label the package with seed name and date. Set the package in a relatively warm place (70 to 75 degrees) such as the top of your refrigerator or on a high shelf. Do not put it in direct sun. (Direct sun could cause it to overheat.)
How Long to Wait: Check Seeds Often
The seeds should absorb water and swell. Check daily for germination and to make sure the paper towel is still just barely moist. Mist it lightly if it begins to dry out.
Depending on which specific plant you are testing, the seeds may begin to sprout in a day or two or may take several weeks to begin. Usually the majority will sprout within a few days of each other. When germination stops and no more seeds have sprouted for several days, you will know what approximate germination rate to expect from that batch of seeds.
How to Interpret Seed Germination Test Results
Seed viability decreases over time and under poor storage conditions, so expect reduced germination of old seeds compared to fresh seeds. You may need to plant more seeds than usual to yield the desired number of plants. Use your test results as a guide. For example, if only half of your test seeds germinate, you now know to take that into account at planting time and plant twice as many as usual. If very few of the seeds germinate in the test, you should probably buy fresh seed.
Perennial Flower Gardener Alert: Stratification of Perennial Seeds
Caution flower gardeners. The above test works well with annual flower seeds and with vegetable seeds. The test is not as useful with perennial seeds because many perennial seeds require stratification before they will germinate. (Not sure what’s an annual and what’s a perennial? Check Annual or Perennial here.) If you are growing perennials from seed, also check Special Seed Germination Tips and How to Cold Stratify or Chill Seeds.
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