The Storage Life of Seeds

I spent part of today talking to a retire Professor from the California University system.  His expertise is in plants, particularly tomato plants.  The subject we discussed was the long-term storage of plant seeds.  Based on his many years of experience he said that the best method is to store seeds in a paper sack in the refrigerator.  In his opinion, the preferred temperature to store seeds is 50 degrees.  For practical purposes, a refrigerator works well.  He recommended against freezing your seeds.  High heat will also shorten the storage life of seeds.

He has germinated tomatoes seeds that were 50 years old that had been stored correctly.  On one occasion, he received wheat seeds (wheat berries) from a cave in South America that were several hundred years old and they germinated.

If seeds fail to germinate, he said it is often because the seed coat has become hard.  He said that you can soften the seed coat by soaking in them in a mixture of two parts water to one part chlorox for thirty minutes.  Then rinse them in clean water and plant.  This will not always work but is well worth a try.  He told me the story of another Professor who had some tomato seeds that would not germinate so they were fed to his turtle.  After going through the digestive track of his turtle, the seeds were then discovered to germinate.

The length of storage life varies from plant to plant.  However, most plants seeds should last a few years.  Legumes have a short shelf life compared to tomatoes.

The following is additional information that comes from the University of Colorado.

  • Vegetable and flower seeds may be kept for one year without appreciable decrease in germination.
  • Storage may be extended to 10 or more years under proper conditions.
  • Seed moisture and storage temperature are the most important factors in determining how long seed can be stored.
  • The drier the seeds are, the longer they will store.

A 10-year storage life can be achieved by drying seed to less than 8 percent moisture. To do so, dry seed at 100 degrees F for six hours. Obtain this temperature by spreading the seed out in direct sunlight. However, because sunlight is harsh and easily can exceed this temperature, drying in the shade is better.

When seed moisture and storage temperatures are low, the presence of oxygen has not been shown to be a factor in seed longevity.  Germination is unaffected by storage in atmospheres of nitrogen, carbon dioxide, partial vacuum or air.

Beans and peas are particularly subject to the seed coat hardening therefore should not be dried as completely as other seed. If they have been over dried, they germinate better if exposed to a humid atmosphere for two weeks before planting.

I mentioned that he did not recommend freezing seeds.  The problems are several.  If you have frost-free freezer the temperature varies during the defrosting cycles.  Seeds need to be thawed out slowly; a sudden exposure to hot humid air can cause them to become moldy and not germinate.  Some tropical seeds cannot tolerate freezing.

Howard

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7 Responses to The Storage Life of Seeds

  1. David says:

    thanks, good stuff

  2. This was just the info we were looking for. Many Thanks

  3. jay says:

    I worked for a large wholesale dealer and grower of ornamental, herb & tree seeds. There have been studies within the industry going back 100 years with same results you mention. Keep ’em dry, keep ’em cool, don’t mess with them too much. Soak to increase germination rates. Some seeds require chilling (stratification) or other manipulation to the seed case (scarification, sanding, heat) in order to germinate but these are usually larger seeds, for instance nut or fruit tree seed.

    Pure live seed tapers off in small seeds gradually over a period of 4 – 10 years, (tomatoes are especially vigorous) so that even after some years there may still be germination at low percentages ie, 12% or other number. The idea being that even if the seeds are old, in a shtf situation you may still be able to germinate some old seeds in order to grow them out and collect a full harvest of seeds for future crops.

  4. Ron says:

    Just started some crown vetch seed – particularly hard coats. A nice flat of them can be started and replanted in troublesome areas with little fuss. I just lightly scuff the seeds between two layers of 1000 grit wet/dry sandpaper and then place in a moist ( wet ) set of peat containers and have almost 100 % germination with two year old seeds.

  5. carol scott says:

    Learned something new today. thank you

  6. Zeb says:

    A 73 year old friend of mine has been using the same tomato seeds that he and his great-grandma planted when he was a kid. He has given a lot of them to friends and family. Well, he lost his seeds awhile back but a friend of his had froze the seeds that my friend had given him. They had been frozen for eight years. He planted them and had a bumper crop.

  7. Pat says:

    Very helpful! I once planted the remains of fish that were caught and cleaned next to my roses since roses love fish emulsion and it sprouted corn in the container because the fish had ate the corn.

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