how fresh are leftover seeds? viability, and vigor

Seed-Viability2015editTHE SEED CATALOGS are here, and I’m getting organized. Step 1: taking inventory of what’s on hand. But how many of the seeds I have left over are still not just viable, but also have sufficient vigor to perform well start to finish?

That’s the sort of “advanced” question I’m wondering about now, after a little episode with a packet of leftover collard seeds that I was feeling so smug about—a feeling that quickly changed to dismay a couple of weeks into their sorry time outdoors.

When taking inventory, first I refer to the general guidelines for how long seeds last, summarized generally in the chart above, and detailed in this article on estimating seed viability. I always suggest a germination test of any packets older than about a year (assuming there are enough seeds left for one).

The collards in question, which were in their third year with me, sailed right through; virtually all of them germinated. But in the ground, things were different: They came up, yes, but then just stood there, like miniatures, never developing.

Germination tests predict viability (the ability to germinate), but they don’t accurately predict vigor—the seeds’ potential for uniform, fast germination and subsequent development in outdoor conditions, not the cozier, controlled conditions of a germination test. Life in the field isn’t the same as life wrapped in a piece of paper toweling in a plastic bag indoors on the kitchen counter, or in the special refrigerator unit of a seed-company testing lab (above).

“Seed vigor is a measure of the extent of damage that accumulates as viability declines,” says part of a class curriculum on seed biology at Ohio State University. “Eventually the seed dies, but first vigor declines gradually.”

Like my unfortunate collards.

If I’d had a second packet of fresher collards seeds on hand, and tested it at the same time as the three-year one, I might have seen some differences (emphasis on might, since I am not trained). Perhaps the roots of the older seed would have been less developed, even stubby or non-existent, or the cotyledon (first leaves) might have been in some way visibly deformed, perhaps with one missing, or over all the tiny plants on that paper towel might have looked more crooked or scrawnier than those from the fresher lot.

Maybe like the examples from the Oregon State University seed laboratory bulletin on the importance of vigor testing in agriculture.

There’s no home test for vigor (there are several kinds used in agriculture, where the subject is the focus of continuing fine-tuning). But knowing a little more than I did about vigor when I failed with those deceptively high-germinating collards serves several purposes for me, and that’s why I mention it now.

It makes me think about storing my seed more carefully, and about replacing seed more frequently rather than pushing it. Also—small comfort, but something at least—it makes me realize that last summer’s collard failure wasn’t something I did wrong in the planting or aftercare. Try as they might, those seeds just didn’t have it in them to go all the way to harvest.

Remember: The chart up top of viability in years assumes that you’re storing seed in optimal cool, dry conditions. And also remember: The seed company you bought it from might have stored it for one or more of those years already!

I’m now clear: Just because seed germinates, doesn’t mean that it will thrive.

  1. Beth Urie says:

    Now I understand – penny wise, pound foolish on those 3 yr. old cipollini onion seeds
    last spring… Thank you for the new piece of info.

  2. Betsy says:

    This is great information. I store my seeds in labeled paper envelopes, but I still buy tomato and pepper seeds just in case those from my garden plants don’t germinate.

    I’m lucky to live in a farming community where I can go to the seed and feed and get bulk seed for basic planting needs and share with my family and friends. The okra seeds I harvested this year don’t look right, so I don’t think I will risk it.

    I’m looking forward to buying more heirloom seeds this year and doing a better job of harvesting all my own seeds.

  3. Thanks for the invaluable information–it matches my own experience with our three-year-old potager. Now I don’t feel so profligate! Even with careful storage, it still was hit and miss so now I order fresh seed each season through mail order. What I do though is try to use as much of that fresh seed, even if it is for partial harvest, like beet greens, pea shoots, or temporary ground covers or to grow enough for my own stock for the easy plants (peas, beans).

  4. Patricia in Glens Falls says:

    Good information. When you’re an urban gardener, have limited garden “real estate” in several raised beds and know that other factors during the growing season will impact the plants that start from your seeds – the small investment in new seeds annually is worth it. Thanks for adding to our collective garden wisdom.

    1. margaret says:

      Thanks, Patricia. I agree. I am trying to be more careful with how I store them, and tossing ones after the second year for the most part.

  5. robert a says:

    Thanks for this article, I’m going to print out the chart and post it inside the lid of my seed-hoarding box. I had a couple of years gap in my vegetable gardening (change of house, change of career) but I just couldn’t bear to throw out all those remnants of carefully chosen and beloved varieties I’d accumulated. So this fall I planted a slew of them, and waited…and waited…and waited. It was a good lesson, missing my fall garden. Now I’m determined I will toss anything more than two years old, and reorder all the essentials every year!

  6. Terry says:

    Thanks for this article, it was very helpful. I have a small greenhouse- very small, but I do have a loyal customer base. I want to offer them the best I have, it’s only right. I almost always have leftover seeds, but I always hesitate to use them for the reasons you stated. They might germinate, but how will they continue to grow?
    I have decided to ALWAYS use new seeds for tomatoes, peppers and cukes because they are my primary sellers. Lettuce, broccoli and cabbage I’ll save for one year- but that’s it. I have learned from experience that it is worth buying new seeds every year rather than take a chance on poorly performing saved seeds.
    If I were just planting for myself, I’d probably be more lenient about using older saved seeds, because I would be the only one to suffer if they didn’t do well.
    Thanks always for your fabulously informative articles. I look forward to them in my inbox.

  7. Teresa Marie says:

    This is great data. I almost always do a quick test to determine % viability. I take 10-15 seeds (depending on how many I have. Place them carefully on a paper towel and then place in a glass neatly. I keep the paper towel moist, and then a few days (appropriate to the type of seed) check back to see how many have germinated. This tells me exactly what to expect from the seeds I have on-hand.
    Teresa Marie

    1. margaret says:

      Nice to see you, Teresa Marie. I do the same germination test, though as with my collards last year it was deceptive. They were 100 percent able to germinate…but not vigorous enough to perform all the way through to adulthood. Drat! :) See you soon!

  8. CraftyMG says:

    Good morning,
    Next month Queen Anne’s County (MD)Master Gardeners are having two seed swaps. One in Chestertown, the other in Stevensville. We have collected seeds, directions for folding envelopes as well as a template to give as handouts. The chart will make a nice display item or handout. Thanks.

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