How to test your stored seed for germination

Seeds. Photo by Lynn Ketchum.
Last Updated: 
December 22, 2011

CORVALLIS, Ore. – If you saved seeds from the last growing season and wonder if they will germinate when planted this spring, you can discover the average rate of germination before the planting season begins.

"It's easy to check vegetable and flower seed viability, and it can save you time later when the gardening season begins," said Ross Penhallegon, horticulturist with the Oregon State University Extension Service. "Some seeds remain viable for a year and others for three or more years."

To find out whether a variety of seed will germinate and grow, Penhallegon suggests the following test:

  • Place 10 seeds an even distance apart on a damp paper towel. Roll up the towel and place in a plastic bag.
  • Leave the damp, rolled towel in a warm spot in the kitchen for two to five days. The location's lighting doesn't matter.
  • After the two-to-five days, check the paper towel to see which seeds have germinated.

"The percentage of seed germinating in the towel will give you a fairly good idea how the same seed will do in the garden," he said. "If half the seed did well in the towel, half of the same batch of seed will probably do well in the garden."

Some seed types last longer than others. For example, seed from sweet corn, parsnips, Swiss chard and spinach generally keep well under normal household conditions for only a year. On the other hand, beans, carrots, cole crops, collards, squashes, tomatoes and turnips are good for at least three years.

Seed is best stored through the winter at 50 degrees with 50 percent humidity. Another good way to store unused seed packets is to place seeds in a sealed jar with a desiccant or powdered milk at the bottom to absorb moisture. Store the jar in a cool room or refrigerator over the winter.

To learn more about storing seed, see OSU Extension's "Collecting and Storing Seeds from Your Garden," FS 220, online.

To learn about propagating plants from seed, see the OSU Extension's PNW 170 "Propagating Plants from Seed" online.

You can search the OSU Extension catalog for more than 1,200 items, including publications, books, videos and other educational media.

Author: Judy Scott