Testing Seed Viability

Reader Contribution by Vicki Mattern
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I have unused vegetable seeds in packets leftover from the last several years. Are they still good to plant this spring? 

Stories of viable, 1,000-year-old seeds from Egyptian tombs aside, seed viability depends on the plant species and the seeds’ storage conditions. Under ideal conditions?—?dry and dark, with a temperature in the 40-degree-Fahrenheit range?—?some seeds will germinate well for five or more years. Others will germinate strongly for only a year or two.

Iowa State University’s Department of Horticulture gives the following average seed storage limits for common crops. Seeds aged past these limits will have lower germination rates, and plants that do germinate will grow with less vigor.

Onions:One year
Corn and peppers:Two years
Beans, carrots, peas:Three years
Beets, pumpkins, squash, tomatoes, watermelons:Four years
Broccoli, cabbage, cucumbers, lettuce, cantaloupes, radishes, spinach: Five years 

If your seeds were stored near or beyond their expected shelf life, or in less than ideal conditions, you can gauge their suitability for planting by doing a simple seed viability test. Write the name of the variety on a paper towel with an indelible pen and then moisten the towel with water. Count out at least 20 old seeds of that variety onto the towel, roll up the towel and place it in a plastic bag. Put the bag in a 70-degree location. Check daily for germination. After some seeds have germinated and a week has passed without additional germination, compare the number of sprouted seeds with the number you started with. If the germination rate is 70 to 90 percent, you could use the seeds and simply sow them more thickly.

If germination is less than that, planting those old vegetable seeds would probably be penny-wise and pound-foolish. Yes, you might save a few dollars on seed this year, but your garden will most likely yield many fewer pounds to harvest than if you had planted fresh seeds. Besides, buying new seeds is a great opportunity to experiment with new varieties.

— Vicki Mattern, Contributing Editor 

Photo by Matthew T. Stallbaumer 

Vicki Mattern is a contributing editor for MOTHER EARTH NEWS magazine, book editor and freelance magazine writer. She has edited or co-authored seven books on gardening, and lives and works from her home in northwestern Montana. You can find Vicki on .