Seed Storage and Its Affects on Seed Quality, Viability, and Germination
About "Survival Seeds," "Seed Banks" and other Long-term Storage Products:
Seeds are designed to be planted and not stored for long periods of time. Although myths circulate about people finding ancient caches of seeds that miraculously still germinate and grow, any home gardener will tell you that this is pure fiction. Getting old seeds that they stored in their garage for a few years, let alone 1,000 years in a cave in the desert, is impossible. Likewise, salespeople trying to convince you that they use some special techniques to prepare the seeds that they are offering in such a way that they will survive 100 years or some other such claim is nonsense as well.
Seed scientists using modern technology and carefully developed, species-dependent procedures, can prepare seeds to be stored in cryostasis in facilities called gene or seed banks. However in practical terms, these techniques and the necessary equipment are not readily available to the general public.
Falling for marketing hype and purchasing a "seed bank" collection of "long-term" storage seeds buys you nothing that you could not have purchased at your local garden center or from your favorite seed company. My opinion of these non-seed professionals that pop up in times of societal unrest to make a quick buck off of an unsuspecting gardening public is pretty low.
If you have concerns about current events and are buying a seed collection with the intent of sowing them at some time in the future when you need to "garden when it counts," that is, a life or death situation, I will flat out tell you that it is simply poor planning that will result in failure.
Seeds are designed to be planted. Like any complex set of skills, you need to develop your gardening abilities over time, and seed saving should be the skill that you learn as your method of keeping a continually fresh supply of the seeds that you need to feed yourself, your loved ones and your community. Our goal is to educate you.
Basic Seed Biology:
Under the proper conditions, after a flower is pollinated (fertilized), seeds develop. Seeds consist of an embryo, some stored food material to nourish the embryo into a young plant, a life force, and a covering called a seed coat. Some seeds are tiny and contain very small amounts of stored food while others contain more than the embryo actually needs.
Seed Storage and Germination:
All seeds will eventually lose their ability to germinate and grow. There are many factors that can contribute to this; genetics, environmental storage conditions, etc. Seeds are living organisms that require specific storage conditions in order to remain capable of producing healthy, vigorous plants. High quality seeds are essential to successful vegetable gardening.
While seeds begin the process of losing their viability from the point that they are harvested, with proper conditioning and storage, some species can last for many years. Many vegetable types will maintain germination rates of at least 50% for ten or more years.
For commercial vegetable production where high germination rates are a requirement, the following list provides some guidance:
For home gardening purposes, the average germination rates published by MM. Vilmorin-Andrieux in his book called "The Vegetable Garden" (1885) are useful. Click here to view.
When storing your seeds, be sure to keep them consistently cool and consistently dry. Temperature and moisture are the primary factors that cause seeds to lose their ability to germinate and fluctuations of these speed the process. Excessive seed moisture increases its respiration rate, can contribute to the growth of destructive micro-organisms, attract insect attack, and reduced viability. Most commercial seeds are dried to less than 10% moisture soon after harvest and held in dry storage during packaging and distribution.
Like moisture, temperature has an influence on the seed's respiration rate. As the temperature increases, so does the respiration rate. For short-term storage (one year to eighteen months), store seeds at 35 to 50 degrees Fahrenheit (F) with an air relative humidity (RH) level of 30 to 40%. A rule of thumb for good seed storage conditions are when the F + RH <= 100; the further you can go below a total number of 100, the better.
Aside from the conditions mentioned above, here are a few more guidelines:
- Store in the coolest, driest location available to you avoiding temperatures over 70 degrees Fahrenheit. These conditions are easily met by placing a small packet of desiccant (which maintains a dry environment) into a tightly sealed, airtight (not airless), glass container and place in your refrigerator.
- Make sure that the storage containers are moisture-proof.
- Maintain a fairly constant temperature.
- Prior to planting old seed and wasting valuable gardening time and space, perform a seed germination test.
The reality is that all seeds die over time. Even under professional storage conditions of ultra low seed moisture and subzero temperatures, seed banks must schedule regular grow outs to ensure the survival of seed varieties. Nature intended for seeds to be planted, to live a full life, and to make more seeds.