Testing Stored Seeds

I don't know about your mailboxes, but mine has been groaning beneath the weight of a new season of vibrant seed catalogs, overflowing with the promise of a bountiful summer. Soon I'll make a list of the reliable favorites I wouldn't dream of being without, as well as some tempting "new for 2010" varieties I can't resist (have you seen this stunning heirloom Broccoli Ramonseco?).

Before I place any orders, I'll dig out the packets of seeds left over from last summer and take inventory. But how can I tell if the remaining seeds are still viable? According to Rhonda Massingham Hart in The Dirt Cheap Green Thumb, there's a simple way to test your stored seeds.

Faster germination results in more vigorous plants. To determine how well your seeds have survived storage, perform a germination test. You are looking for a high percentage of the seeds to sprout within the normal time for the plants' type.

• Moisten a paper towel or coffee filter.
• Place 10 or 20 seeds on it.
• Fold in half or in quarters.
• Seal in a ziplock plastic bag. (You can place several "test papers" in one bag.)
• Open daily to check for germination.
• After the appropriate amount of time has passed for that kind of seed, count the number of sprouts to figure the percentage.

Five out of 10 seeds and 10 out of 20 seeds gives a 50 percent rate. More seeds in the test will yield more accurate results. A germination rate over 60 percent is good, better than 70 percent is average, and better than 90 percent is great. The fewer seeds that germinate in your test, the more you will need to plant to compensate. If you know that only about half your seeds will come up, you'll need to put twice as many in the ground at planting time to get the same number of plants as for seeds with 90 percent viability. Of course, the viability of seed varies with the age of the seed, the conditions under which it has been stored, and the type of plant or variety of the seed itself.

— Melanie Jolicoeur, Associate Director of Marketing
Photo: Melanie Jolicoeur