How Long Do Seeds Really Last? (Plus, a Cheat Sheet on Seed Storage Life)

How long do seeds really last? (Plus, a cheat sheet on seed storage life)

The beginning of spring usually sees me sprawled in the middle of the living room floor, with all my ammo boxes, laying out rows and rows of seed packets sorted by vegetable, and then by variety. Some are even color-coded… and I suddenly realize I have a rather strange obsession with collecting 12 different types of purple tomatoes (and counting).

Inevitably, a handful of seed packets get tossed in the compost pile as I double-check the dates… peppers from 2012, onions from four years ago. Yikes.

Some seeds I’ve only sown once or twice but still have half a packet left, some I’ve saved… and saved… and saved… because they’re so easy to save by the bagful every year (I’m looking at you, beans). Still others are rotated every few seasons as I try new varieties, and by the time I make it back to those Parisienne carrots, it’s already been a couple years. Are they still good? Should I get new ones? How long do seeds really last, anyway?

I’ve combed through countless seed sites and extension sites over the years, wondering this very question. And there seems to be no consensus, especially when you take into account the environment the seeds were stored in, the quality of the original crop the seeds were harvested from, even the condition of the seeds themselves, as treated seeds will have a different lifespan than seeds in their natural state.

Seeds have a shelf life (as all living things do), and depending on where your particular shelf is, the viability of your seeds can vary by as much as a year or two. When someone asks, “How long do broccoli seeds last?” a safe answer is three years, but in ideal conditions your seeds could still actually sprout after five.

So, you see where our dilemma lies.

Determining the germination rate of garden seeds

What are “ideal” conditions?

In a perfect world, we’d all have second refrigerators with perfectly controlled humidity levels in which to store our seeds. Our seeds would live in this cool, dark, dry environment and 10 years later, those very first tomato seeds we’d ever bought would still be viable.

In reality, our homes go from hot to cold at the turn of the seasons, we sometimes forget our seed packets outside overnight (or at least I do), and an old shoebox will have to do for storage. We can’t really fault ourselves either; who knows what the seed went through before it even reached the store.

Seeds store best below 40°F with less than 10 percent humidity, tucked inside airtight containers in a dark environment.

Every time a seed experiences less than ideal conditions, it suffers a decline in quality. It may not die right away, but it might take a little longer to germinate. Eventually, it will fail to germinate at all.

Using the baggie method with coffee filters (or paper towels) is a good way to test seed germination. By taking a sample of 10 to 20 seeds and pre-sprouting them in baggies, you can gauge how viable those seeds are before committing to potting or planting them. Less than 50 percent germination rate means it’s time to buy new seeds.

Then, there is the issue of seed vigor.

According to Oregon State University, vigor is the “ability of those seeds to produce normal seedlings under less than optimum or adverse growing conditions similar to those which may occur in the field.” That is, the ability of your plants to survive in the ground outside with all the elements working against them, as opposed to being coddled inside in a cozy baggie.

While a germination test can predict viability, it can’t truly predict vigor — how well a seedling will grow in terms of health, strength, uniformity, and root system, not to mention its production of flowers and fruits. A seedling with compromised vigor may have a missing cotyledon, look stunted or scrawny, or seem overall slower to develop than seedlings from fresher seeds.

Try as they might, sometimes older seeds just don’t have it in them to go all the way to seed again. A will to germinate does not equal an ability to thrive.

Measuring seed longevity and seed vigor

(Image: Oregon State University.)

Are your seeds still viable?

The cheat sheet below takes the average life expectancy of seeds from a variety of sources, including the cooperative extensions of Oregon State University, Colorado State University, Purdue University, and Virginia State University. Consider it more as a guideline, as the longevity of your seeds ultimately depends on the date on the packet and how carefully you’ve stored them since then.

Vegetables Shelf Life
Asparagus 3 years
Beans 3 years
Beets 3 years
Broccoli 3 years
Brussels sprouts 4 years
Cabbage 4 years
Carrots 3 years
Cauliflower 4 years
Celery 3 years
Chard 3 years
Chicory 4 years
Collards 4 years
Corn (sweet) 2 years
Cress 5 years
Cucumbers 5 years
Eggplant 4 years
Endive 5 years
Kale 4 years
Kohlrabi 3 years
Leeks 2 years
Lettuce 3 years
Muskmelons 5 years
Okra 2 years
Onions 1 year
Oriental greens 3 years
Parsnips 1 year
Peas 3 years
Peppers 2 years
Radishes 5 years
Rutabagas 4 years
Salsify 1 year
Spinach 3 years
Squash (summer and winter) 4 years
Tomatoes 5 years
Turnips 4 years
Watermelons 4 years

 

Herbs and Flowers Shelf Life
Basil 5 years
Chives 2 years
Cilantro 2 years
Fennel 3 years
Oregano 4 years
Parsley 2 years
Sage 4 years
Annual flowers 1 to 3 years
Perennial flowers 2 to 4 years

 

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March 17 2015      32 comments     Linda Ly
Semillas

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  • Carrot Top

    I have been gardening on a budget for over 30 years. When I bought my first house, the old fellow who sold it to me left some tomato seeds. If I remember correctly they were early girl and judging by the packet they were several years old. I used these seeds for 16 years until I sold the house and left the seeds for the new owner.
    One of the last crops that I grew in that house included paprika peppers. I dried them and used them in the kitchen until they were almost all used up. 14 years later, I found one dried pepper in my kitchen cupboard and decided to try the seeds for viability. I planted 12 seeds and all came up on the 3rd day. I gave most of the plants away but grew 4 of the remainders. One plant alone has provided 35 peppers 8-10inches long.
    In both cases I did nothing special to preserve these seeds. They were simply kept in a dry place.

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  • WatchingThe End Of Democracy

    First I would like to thank you for all the time and work that you put in this study. I want to use this to judge how long to keep my seeds. But, are these seed expectancies base on shoe box storage or refrigerated storage?

    • Regular shoebox storage in cool, dry conditions. 🙂 If you refrigerate your seeds and keep them at ideal humidity levels, you can expect them to last even longer.

      • WatchingThe End Of Democracy

        Again thank you. 🙂 I will print this time table out and put it in the shoe box with the seeds.

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  • Debbie Tegart

    I love the water and paper towel germination test. That let’s me know if I am good to go or not. I have an obsession with seeds and yes some get really old….

    • Obsession with seeds? I have no idea what you’re talking about. 😉

    • tessagds

      I am too obsessed with seeds… when I go to farmers market I save the seeds on what ever I picked up… but when I grow them and which they come out healthy and full of life and by the time they flower they never bear fruit.. I would assumed farmers market that claim themselves organically grown will have no chemical to prevent from re producing thru their seeds… I am lost… I want to see what I plant and know were its coming from…. do you think this local farmers market are in just for the fad of locals wanted to support locals…

      • Only heirloom and open-pollinated varieties produce stable seeds that stay true to the breed. (Read more about this in my seed-saving post: http://www.gardenbetty.com/2011/09/a-guide-to-saving-and-storing-seeds/ )

        If you saved the seeds from hybrid vegetables and tried to grow new plants with them, they may produce sterile seed, or produce fruits that don’t resemble the parent plant at all. There ARE organically grown hybrids, but they’re not ideal for seed saving.

      • Aaron Wolfe

        The reason why that happens is most fruit is harvested when they first become ripe. But in order to save seeds from them they need to stay on the vine a lot longer.

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  • Thank you for the handy list! Like many, I just had no idea what to expect from my old seeds. I definitely had some failures this year: 3yo onions and 4yo spinach. I’m still waiting to see what happens with some 3yo peppers. I think it’s time to edit my stash!

    • This year I combined all my leftover carrot seeds from a few years ago and just broadcast them into a tray… whatever decides to spring up will be a bonus this season!

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