At this time in the year, the garden is all planted and I have left over seeds. Since my garden isn’t huge, I seldom use an entire packet of seeds in one year. For some plants, like grape tomatoes, the packet has 25 seeds and I grow one plant each season; that packet will keep me in grape tomatoes for years.
This brings up the whole issue of seed storage. Seeds are alive and the two biggest factors that affect their viability are moisture and temperature. To make a seed germinate, you need to give it water and warmth; to store seeds for the long-term, they need to be kept dry and cool.
There are lots of sites online giving information about storing seeds and many of them make it seem like a big process to keep your seeds from year to year. A number of seed companies offer seed storage kits that include special containers and desiccant to keep the seeds dry, all at a premium price.
If you’re planning to store seeds for 10 or 20 years, then being very exact with the moisture content of the seeds and the storage temperature makes sense. But if you’re like me and you just have some packets of seeds that you didn’t used up this year, seed storage is pretty easy. In fact, if you’re only keeping them for a year, leaving the packets on a shelf in your house is fine! Almost all of the standard vegetable and flower seeds need no special treatment to remain viable for one year.
Since a packet of seed will sometimes last me 3 years or more, I do keep moisture and temperature in mind when I store my seeds. I’ve found that putting them in a tightly sealed container and keeping them in the house works well.
The one place I wouldn’t put seeds is in the refrigerator. There are two problems with the fridge. The first is that a refrigerator is very humid. Unless the seeds are tightly sealed, the moisture will get into the packets. The other issue is ethylene. This gas is produced by aging and damaged plant tissue so if you have vegetables or fruit (esp. apples) in your refrigerator, there will be a lot of ethylene gas. Ethylene shortens the life of a seed by causing premature aging. Because the risks of moisture and ethylene don’t outweigh the benefits of the cooler temperature, I just keep my seeds in a cupboard away from sources of light and heat.
All in all, I don’t worry too much about seed storage. I keep them dry and try to keep them cool. I’ve never had a problem with seeds germinating even after a few years of this very basic storage. To me, it’s just one more example of how tough plants – in this case, seeds – really are.