Recently I posted about how to determine the viability of old garden seeds using a germination test. Amazingly, some seeds may still germinate 5, or even 6 years after their original purchase. Don’t assume, however, that any and all seeds you have left over are still viable, especially if you failed to take special care in how they were stored.
So how should we properly store our leftover garden seeds? Experts tell us that there are three major factors that affect seed viability; temperature, light, and moisture. By controlling these factors, we can ensure that the seeds do not sprout or decay while in storage. For long term storage, garden seed packets can be placed in sealed glass jars, or in plastic or metal containers and then stored in a cool, dark place.
If you harvest your own seeds, resealable plastic sandwich bags are a great storage option. Label your bags with crop and year with any special notes, and then place them in a glass or plastic container. The optimum place to store seeds for the winter is in the refrigerator or freezer where temperatures are consistently below 40 degrees. After removing your airtight containers from cold storage, wait until the container and seeds have reached room temperature before opening them. When freezing-cold seeds are exposed to the warm moist air in your home, water may condense on the seed’s surface, initiating germination or creating an opportunity for mold to develop.
If you have limited space to store seeds in your refrigerator or freezer, search for an alternative storage location that is dark and consistently cool, between 50 and 60 degrees. If your cellar is mostly unheated during the winter months this should work well. Light may cause your seeds to germinate in storage, so ensure the seeds are always kept in the dark. Seeds that germinate and sprout cannot be put back into a dormant state and are no longer viable. When in doubt about viability, do a germination test on your seeds.
I recently browsed through the “Territorial Seed Company” catalog, which had arrived in the mail and I was surprised to notice that it provides the storage life for nearly all the seeds in their inventory. This is such useful information! Suppose you purchase a packet of tomato seeds and you only want to plant a small number of these seeds. It’s great to know that you can store the remainder for next year. You can also use this information to determine which crops you can purchase enough of for several years without waste, earning a bulk discount. Territorial Seed Company also notes which of their seeds yield plants you can save seeds from for the following year, more useful information for those of us looking to increase our self-sufficiency!
In general, those seeds that can only be stored successfully for 1-2 years include leeks, onions, spinach, peppers, and corn. Those that remain mostly viable at 2-3 years include beans, peas, beets and chard. Most crops in the “kohl” family last 3-4 years, including broccoli, cabbage, kale, brussels sprouts and cauliflower. Melons, cucumbers, and others in the squash family also tend to store well for 3-4 years, as do tomatoes and carrots. Lettuce and radish seeds can last as long as 5-6 years while staying viable.
Using good storage practices with leftover, or recently harvested seeds can save you money when ordering seeds for the next gardening season. Give it a try this year!
Ken Kogut has been a Master Gardener Volunteer since 2014. A retired NY DEC Natural Resource Supervisor and Wildlife Biologist, Ken now spends his time maintaining his garden, berry patches, and small orchard with a goal of living sustainably off his property. He particularly enjoys helping county residents solve their gardening issues, writing short articles for gardeners, and teaching new gardeners in Seed to Supper classes.