I was recently with my sisters and they were asking me if they could use up their old seed packets from last year. My answer was a resounding yes! New gardeners often don’t realize that most seeds are still ok after the year they bought them.
Most seeds have at least a 3 year shelf life. There are a few seeds that have a one year shelf life, like onions, but that doesn’t mean they all won’t sprout at all on year 2. Instead, it usually means germination rate drops significantly to less than 50%.
I have successfully sprouted 2 and 3 year old onion seeds but I usually plant them thickly knowing they will have a lower germination rate.
Knowing how long seeds last for saves a lot of frustration because if a seed is past it’s usually shelf life, you can accommodate for it. I adjust by either sowing a lot of extra seeds or buying a new pack of seeds.
Of course, there is the option of doing a germination test to see if the seeds are still viable. For me personally, I’m often too busy to test or don’t have enough seeds left to do an accurate test. If you would like information on how to do a germination test at home you can find it HERE.
How Long Do Seeds Last? Seed Viability Chart
In preparing to share information on how long seeds last for, I did a lot of research to discover the most accurate number of years. It was a bit frustrating because sources vary widely.
Part of this is due to different varieties and part due to how the seeds are stored. Instead of giving a wide range, I opted to take the average of three reputable sources as well as my own experience to create the chart and numbers below. The numbers on this chart assume that the seeds are stored in ideal conditions.
Chart Sources:
- https://extension.colostate.edu/topic-areas/yard-garden/storing-vegetable-and-flower-seeds-7-221/
- Ashworth, Suzanne. Seed to Seed. Seed Savers Exchange; 2 edition (March 1, 2002)
- https://hortnews.extension.iastate.edu/1995/3-3-1995/seedv.html
What are Ideal Conditions for Seed Storage?
In order to get your seeds to last a long time, it’s best to store in ideal conditions. So what are ideal storage conditions?
After the seed is thoroughly dried, it should be stored in a moisture proof container, like glass or metal. Moisture is the enemy of stored seeds and they will lose their storage life very quickly when exposed to it.
After storing in an airtight container, seeds should be put in a cool, dark, and dry area with very little temperature fluctuation.
Long Term Seed Storage
If you are looking for long term storage options for the seeds the best way to store them is to freeze them. The seeds should be completely dry and stored in an airtight container.
Freezing can have a negative effect if the seeds aren’t thoroughly dried. An easy test for this is to fold the seed in half. If it bends it’s not dry enough, if it breaks it is dry enough to freeze.
If for some reason your seeds aren’t dry enough, an option is to place a silica gel pack inside an airtight container with the seeds for a week at room temperature (silica is a moisture absorbing material). Then after a week of allowing the silica to absorb the moisture from the seeds, remove the silica from the container. Reseal the container and then freeze.
Seeds stored in a freezer can last up to ten times as long as mentioned in the chart above.
Conclusion
Knowing the basic time period of how long a seed is viable (sprouts successfully) can really help give you a good idea of what seeds to keep and what seeds to toss after a certain time period. You can also use it as a tool to determine if you will plant a few more seeds because of lower germination rates. I find knowing an estimate of how long seeds last to be very helpful in my own seed starting efforts!
