Most seeds are able to germinate at least 2 to 3 years after harvest if they have been kept dry and not too hot; some in fact are good for 7 years or more. (For a list of seeds of some 150 common garden plants and their normal conservation time under home conditions, see Are Last Year’s Seeds Still Good?).
But what gardener has never found an old pack of seeds left in some forgotten corner, seeds you suddenly want to try again? But if you sow them and they don’t come up, you’ve wasted pots full of sowing mix or space in the garden and lots of time. Isn’t there are way to test the germination of older seeds before you actually sow them?
Fortunately, there is. And it’s very easy to do.
Quick and Easy Germination Test
A few weeks before the intended sowing date, place ten seeds on a piece of moistened paper towel and fold the paper in half, covering the seeds. Now, place the folded paper inside a clear plastic bag, seal it and move it to a warm location. After 3–21 days (depending on the type of seed), you should have germination … if the seeds are indeed still alive.
- If 7 or more seeds germinate, the seeds are still in very good condition and you can sow them as usual.
- If 4 to 6 seeds germinate, their germination is below par, but still reasonable: sow them twice as thickly as you would normally.
- If 3 seeds or fewer germinate, the seeds are well past their prime and, unless the variety is irreplaceable, sowing them will probably not be worthwhile, as the seedlings will probably germinate at an even lower rate in soil. Besides, even if they do come up, weak seeds tend to produce feeble or unhealthy plants. Time to get out and buy fresh seed!
Article originally published on February 2, 2015.