1. Think dry and cool no matter where you store seed. Humidity and warmth shorten a seed’s shelf life.
2. Keep seed packets in plastic food storage bags, plastic film canisters, Mason jars with tight-fitting lids, or glass canisters with gasketed lids.
3. The refrigerator is generally the best place to store seeds.
4. Keep your seed-storage containers well away from the freezer section of your refrigerator.
5. To keep seeds dry, wrap 2 heaping tablespoons of powdered milk in 4 layers of facial tissue, then put the milk packet inside the storage container with the seed packets. Or add a packet of silica gel. Replace every 6 months.
6. Store each year’s seeds together and date them. Because most seeds last about 3 years, you’ll know at a glance which container of seeds might be past its prime when planting season comes.
7. When you’re ready to plant, remove seed containers from the refrigerator and keep them closed until the seeds warm to room temperature. Otherwise, moisture in the air will condense on the seeds, causing them to clump together.
8. If you’re gathering and saving seeds from your own plants, spread the seeds on newspaper and let them air dry for about a week. Write seed names on the newspaper so there’s no mix-up. Pack the air-dried seeds in small paper packets or envelopes, and label with plant name, date, and other pertinent information. Remember, if you want to save your own seeds, you’ll need to plant open-pollinated varieties. They’ll come back true; hybrids won’t.
9. Or dry saved seeds on paper towels. They’ll stick to the towels when dry, so roll them up right in the towel to store them. When you’re ready to plant, just tear off bits of the towel, one seed at a time, and plant seed and towel right in the soil.
10. Even if you’re organized, methodical, and careful about storing seeds, accept the fact that some seeds just won’t germinate the following year. Home gardeners will find that stored sweet corn and parsnip seeds, in particular, have low germination rates, and other seeds will only remain viable for a year or two.