GERMINATION TESTING of leftover seeds would make a good science project for grade-school kids, and it can delight and inform big people, too. If you can count to 10, you can test last year’s seeds for viability, before wasting money on unnecessary replacements.
Most are viable three to five years, but there are exceptions. Gather a couple of zipper-lock plastic bags, sheets of paper towel (one per variety being tested), small plastic labels and an indelible marker. Count out 10 seeds of each kind being tested, place them in a row on a damp paper towel, and roll it up, with the label marked with the variety name rolled inside, too.
Put the whole thing in a plastic bag (you can put a number of these rolls into one large bag) and leave it in a warm place. Check it after a few days, and again after a week, and so on, and make certain things stay moist inside.
Count the seeds that have germinated, and multiply that number by 10 to get the percentage of viability. If eight seeds are alive, your packet it approximately 80 percent viable; go ahead and use it. If only three germinated, you should re-order—or sow very heavily if you have a lot of seeds left, or only need a few plants.
Some people like to wait till later on, close to outdoor planting time, to do their germination tests, particularly with the large seeds such as peas and beans. Then, the ones that sprout are used right in the garden, so the germination test doubles as a pre-sprouting process, speeding things along and reducing the chance of failure in cold springtime soil. Even if your budget is large, try this experiment. There is nothing quite so extraordinary, nor so humbling, as the sight of a cotyledon, or seed leaf, pushing out of a seed—a botanical baby being born.