estimating viability: how long do seeds last?

Seed viability chart for garden seeds: How long do seeds last?NO WONDER I AM CONFUSED ABOUT how long seed lasts; every expert has a slightly different take on the matter, making memorization of any absolute rules impossible. As I’ve been looking through my on-hand supply of leftover vegetable seeds, in particular, I kept saying to myself, “Now does lettuce last two years or five?” and knew it was time once and for all to make a handy reference chart comparing how long different seeds last, according to whom.

Most seed will last a couple to several years—but there are disclaimers to even that general a statement. As living things, seeds are perishable, particularly if not kept cool and dry (such as in a tightly sealed jar in the refrigerator or freezer). Humidity, in particular, is death to seeds.

Treated and pelletized seed will also have a different shelf life from seed in its natural state. The condition of the original crop the seed was harvested from will also, of course, affect its perishability.

The years of viability in my chart above, then (citing Fedco and Johnny’s Selected Seed catalogs, and the Iowa State and Vermont extensions) are averages, not guarantees—and all presume responsible storage tactics (not that you left the packet in a wheelbarrow in the garage all summer, or in your overalls pocket).

SO WHERE IS THERE CONSENSUS? Onion seed lasts just a year, everyone seems to say, with parsley and parsnips other very short-lived in storage. Muskmelons last about five years; watermelons slightly less. Corn about two, maybe three, and likewise for peas and beans. But you can see the disagreement around things like lettuce (some say two, some six years) and spinach (one to five).

The best way to go to be sure if your leftover seeds are viable: Do a germination test. But this is tricky when you bought some great heirloom pumpkin and there were just 20 seeds in the packet and now only half those remain.

Next best is an educated guess based on what’s the date on that packet, and how carefully you cared for it the last year. Safest of all: the educated guess and a backup supply of anything where you might be caught short if the calculation proves wrong.

If it turns out you don’t need the new backup seed, you can always use it next year. Well, unless it’s onion.

more help from expert sources:

30 comments
January 28, 2011

comments

  1. says

    Glad you included doing a germ test. Seed storage is about gradual loss. You don’t need to throw your seeds away (a.k.a compost) based on how long you’ve stored them. Seeds are alive, during storage they are using their internal resources to stay alive until the right conditions turn up. For seed sellers like us, less than 75% germ rate is too low to sell, but for home gardeners you can still plant your saved seeds, even at less than 50%. Our local heirloom Hank’s Baking Beans were in an open container in a basement for at least 6 years before they were rediscovered. Enough germinated that we brought the variety back from the brink. Seeds are survivors!

  2. says

    Good to know about onions. This is my first year planning to plant onion seeds (last year, I did sets). I will plant every one of them and buy new next year.
    Otherwise, I keep seeds two years tops. I may go ahead and plan on new parsley seed each year too because last year, my parsley crop was sparse with the 2 year old seed.
    Thanks for the info.

  3. says

    The seeds for the wax beans I planted last year were easily 10+ years old, stored in my refrigerator in a zip lock. I planted them more thickly than usual, but it was hardly necessary. For gardeners, I say go ahead and try them. If they don’t germinate, you can always follow up with newer seed or something else.

  4. Stacy M says

    Margaret,

    I just found your blog and I must say it is one of the best I’ve seen! The information is fantastic and your garden is stunning. Thank you for sharing with us! I also listened to your podcast and really enjoyed it. It’s nice to hear about gardens on a cold winter afternoon!

  5. says

    Always trust the seeds. I have been surprised time after time over the past 30 years by how well they germinate, even when 10 years old or more. Store them cool, dark and dry. I have never found the documentation for all the different guesses for longevity in seeds. My opinion now is that they are all made up, one source copying the other and changing things slightly. I can’t find where anyone did a 10 year test to see exactly how germination declined in vegetable species. If you find it, let me know. Your readers can find online seed saving instructions from the website of this 20 year-old non-profit:

    http://www.seedsave.org/issi/issi_904.html

  6. says

    I had 5 years old beans and the germination rate was about 80%. You just never know, brassicas last long for sure and tomatoes too, and it all varies, you have to test properly sometimes people writing to me that they had a low germination rate, but hey that depends on lots of factors. I had 100% with something and then if somebody messes the process up (luck of water, low temperature etc.) the germination rate can be significantlyu lower.
    Great post by the way :)

    • says

      Welcome, Stacy; how sweet of you to be so encouraging. Come back and spur me onward anytime. :)

      Welcome, Seedparade. “You just never know” is exactly right. Nice to “meet” you.

  7. Brian G. says

    This is extremely helpful, thank you. The germination test is not for me. The last time i tried I completely forgot about the baggie of moistened seeds on top of my refrigerator. I forgot until I tracked down the horrendous mystery smell in my kitchen. Talk about an ‘uh oh’ moment.

  8. Terryk says

    I also received an email from John Scheepers that gave start times from frost date for vegetables and flowers which is also good for planning the garden chores. With all this info it must be getting closer to spring. I wish I knew how to share the info with everyone.

  9. Terryk says

    Brian I just read your comments on the germination test. I did mine but put it in plain view otherwise I would have been in the same boat as you. Even after a week it did smell a bit musty.

    The good news is I had great germination on most things.

  10. Terryk says

    Thanks Margaret, I am sure your list will be very helpful. I am sitting here at the kitchen island with my iPad and seed Catalogs (even have my cat on the next chair). I would imagine it resembles your house.

    Have you ever grown artichokes? Or have you ever done an indoor project of growing salad greens to get the season started early? I am thinking of experimenting in a few weeks growing some of the cold tolerant, quick growing greens in a porch area of the house. Any comments?

  11. says

    What is the story on drying seeds from things you grew. I dried some pumpkin seeds from my french pumpkins to plant this Spring. I have been told they will be sterile and will grow but not produce pumpkins.
    dd

  12. says

    I generally try, planting more closely the older the seed. I’ve never had zero germination, and once whatever it is comes up, I can always sow more of it with fresher seed if needed.

    Slow-germinating (at least for me,) seeds like most peppers, I tend to stick with fresher seeds to make sure I don’t lose too much time while waiting for germination. I’ll still try to use the older seeds, anyway, just plant more of them to account for the lower germination rate. (That’s probably why I end up with too many pepper plants for my space most years!)

  13. Sandra says

    Hi Margaret,
    This is such a helpful post – like all your posts. I just wanted to thank you for helping me in so many ways whether it is recommending a better potting soil, ideas to keep me on track buying seeds, recommending great plants that are new to me, and just generally being my garden guru. Thank you so much
    Sandra

  14. says

    That was an incredible post Margaret, thankyou! My Maine based business Fernish L&D is in hibernation, probably ’till mid-March at this rate, but we’ll be starting seeds this week hopefully to ward off the SAD that afflicts those kept indoors for so long away from the plants we love, again THANKYou for your passion!
    Joel

    • says

      Welcome, Fernish. Sounds like you you share the passion. Lots of snow here this week again…shoveling, shoveling…but before we know it there will be signs of spring. Well, once we get through February and much of March, anyhow. :)

  15. Michelle says

    Keep in mind there were seeds found in the pyrmaids and they planted them and they grew. A lot has to do with the enviroment in which they are left. I have some that no matter how old they are they seem to be eager to sprout and some that are only a year old that nothing you do will encourge them to even try. Everyone has different times because everyone has different experiences and no one is going to have the exact same. Now if I can make the sand in FL coorporate all would be well…until then pots and pots and more pots!

    • says

      Hi, Michelle. Yes, isn’t it amazing how long some have been found to last in that perfect type of “storage” environment? And your sandy sounds like quite the formidable opponent. Yikes.

  16. says

    Do you have any ideas how long flower seeds last? I seem not to have luck with older comos and zinnias just from my experience… but it could just be bad luck on my part. Any advice? Thanks!

  17. says

    I’ve always had good luck growing bean seed that has even attained the age of 5 years. Two years ago I received beans from a woman in California who had a certain variety stored in her basement in a jar in a freezer that simply had the door closed. The freezer was not running. The seed she sent me was from her 2004 year bean seed harvest. I planted some of this 8 year old seed last year in 2012 and got nearly 100% germination. I saved half of that 2004 seed to try again this year in 2013. This year that 9 year old seed has given me nearly 100% germination again. When I received the seed from her I simply placed it in baby food jars and stored it on a shelf in my basement in which the temperature varies from winter to summer from about 60 degrees farenheit to about 68 in the summer. I also suspect there maybe a variation in the length of viability of various varieties too. I don’t know what the humidity level of this woman’s basement in California is, but it seems to me that the coolness of the storage enviorment is a big plus. I have a few seeds left over of this now 9 year old seed and I’m going to plant the rest of it next year in 2014 when the seed is close to 10 years old.

  18. says

    This is a great share, Margaret! Thank you :). After doing professional lab germination tests on every kind of seed for multiple years, I have found that most seeds – assuming they are stored cool, dark and dry – will store for MUCH longer than the estimated viability timeframes. That said…when in doubt, a germ test and/or another packet of fresh seed from a trusted source never hurts!

    Your website is wonderful…thank you for all you are providing!

    best,
    Justin

    • margaret says

      Thanks, Justin. I keep visiting your website and hope that we will be in touch for real soon.:) Maybe an email — I will write and say hello!

  19. Bill Sullivan says

    I planted some pretty old onions last winter into flats 2 or 3 years old and I was surprised at the high germination rate. I can’t give you an exact number but I bet 75% germinated. I would always do the germination test before I discarded any old seed. My oldest lettuce I usually mix together and densely seed as a cutting lettuce. Thanks for your list I was looking for some kale as there is such a shortage this year and found a good amount of seed from years past, no kale but lots of other good stuff!

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