by Sandy Swegel
That’s a great question that comes up every year during our end-of-the-year Fall Sale. Everybody wants a good deal but are afraid the seeds won’t still be good next year.
The answer is as expected…”It depends.”
If you can keep your seeds in a cool dry place, your seeds can last for years.
Here are the seed killers:
Excess Moisture. The year we had catastrophic flooding in Boulder the seeds in my storage area sprouted right in their packets up on a shelf from the high humidity from only one inch of water on the floor in September. The seeds were well packed out of the water, but the temperature was 85 degrees and the humidity 100%. If you live in a humid area, you can save all those little silica gel packets to reuse.
Excess Heat. Seeds do survive better in cooler temperature. A cool basement, a cold closet, or a freezer. The actual temperature is a little less important than keeping the temperature consistent.
Light. Some seed germination is triggered by light (lettuce is an example) so keep your seeds dark by storing in a dark bag or box.
Rodents. It seemed like a good idea to keep the seeds in a shoebox in the unheated garage. Cool and dark. Then in early Spring, I discovered little mice had chewed right through the cardboard box and chewed the seed packets to get at the yummy treats inside. Ewww.
What works for me is to put the seeds in mason jars that I keep in a cool dark basement closet in a closed box.
Once you know you can keep the seeds cool and dry, then the only thing to consider is seed longevity. Some seeds last easily for years. Others only last one year before the germination rate goes down. Below is a chart from the Chicago Botanic Gardens on longevity in vegetable seeds. Some of the really good “keepers” are ones you only need a few of every year such as tomatoes and squash.
Seed Viability Chart: