SAVING AND STORING SEEDS – By Dennis Adamson

By Dennis Adamson on Feb 12 in Blog tagged all over the world, Dennis Adamson, flower seeds, garden seeds, germination, humidity, light, saving, Saving and storing seeds, seed vault, seeds, sprout, storing, temperature, vegetable seeds | Comments Off

There are national and world organizations that are maintaining seeds to secure biological diversity, protect against regional or global catastrophes..

The mission of the National Center for Genetic Resources Preservation (NCGRP) in Ft. Collins, Colorado is to acquire, evaluate, preserve, and provide a national collection of genetic resources to secure the biological diversity that underpins a sustainable U.S. agricultural economy through diligent stewardship, research, and communication.

Seed in the NPGS base collection comes from USDA-ARS-NPGS regional or crop specific field sites. This consolidated collection of all of NPGS holdings is stored at the NCGRP in secure freezers at -18°C.  The viability of stored seeds is periodically monitored using standard germination assays.  A fresh sample of seed is obtained if seed supply is too low or germination percent decreases below about 60%.  Seed longevity depends on storage conditions and seed quality. They expect most undamaged seeds that are properly dried to survive about a hundred years in conventional storage (-18C) and about a thousand years under cryogenic (liquid nitrogen) conditions.  Approximately 10 to 20% of angiosperm species produce seeds that do not survive complete desiccation. These so-called “recalcitrant” seeds (Examples are oak seeds, wild rice, and citrus) also do not survive conventional storage conditions used in gene banks. However, seeds from many of these species are amenable to cryopreservation.

The Svalbard Global Seed Vault represents a global effort to safeguard plant genetic resources for future generations.  This vault is located about half way between the North Pole and the coast of Norway, near the town of Longyearbyen (population 1900), in the remote arctic island archipelago of Svalbard. Constructing the vault required drilling a 390 feet tunnel into permafrost on the side of a mountain on Spitsbergen Island.  The vault consists of three large concrete chambers that collectively have the capacity to hold 3.5 million seed samples.  Seed of crops important for food and agriculture will be safely stored for hundreds to thousands of years, protected from global or regional catastrophes.  Participation in the Svalbard Global Seed Vault endeavor gave the United States a visible presence in the worldwide effort to safeguard the genetic diversity that underpins our food supply.  The worldwide effort to preserve seeds is consistent with the philosophy that genetic resources are global assets. The historic opening of the Svalbard Global Seed Vault was celebrated 26 February 2008.  Over 11,000 NPGS samples were included in the initial shipments of seeds from all over the world.

Of course we don’t have the possibility of storing seeds under these conditions.  There are factors that we can control to prolong the viability of our seeds.

1. Humidity: Susan Stieve, curator of the Ohio State University Ornamental Plant Germplasm Center, said that too much moisture is the biggest contributing factor behind seed deterioration.  The higher the seed moisture content, the quicker the seed quality will degrade.  The most important thing is to keep the seed as dry as possible.  Every 1 percent decrease in seed moisture content doubles seed storage life.
2. Temperature: Stieve said that growers and seed companies can also follow a few basic rules of thumb when keeping temperature in check. Every 10 degrees Fahrenheit decrease in storage temperature doubles the seed storage life at temperatures above freezing.
3. Light: Seeds should be stored in a dark environment.  Light degrades the viability of stored seeds.
4. Rate of seed degradation: this depends on the type of seed that you have and the overall storage life of the plant, said Stieve. Understanding what type of seed you have and its relative storage life is the first step to effective seed storage.  She added that seeds represent only 5 percent of production costs, so growers should consider the risk of planting stored seed as opposed to purchasing new seed.  Old seed loses strength. Germination tests will not indicate seed strength, which is sometimes called “vigor.”  Use of good seed is very important. Buy only from dealers who have a reputation for handling good seed.  Many vegetable diseases are transmitted through seed and planting diseased seed often results in severe losses,  according to the University of Alabama Division of Agriculture.

The following chart can help you determine how long you should try to store your seeds at home.

Virginia Cooperative Extension: Virginia Tech

Viability of Vegetable Seeds (Average number of years seeds may be saved)
Vegetable	Years
Asparagus	3
Bean	3
Beet	4
Broccoli	3
Brussels sprouts	4
Cabbage	4
Carrot	3
Cauliflower	4
Celery	3
Chinese cabbage	3
Collard	5
Corn, sweet	2
Cress, water	5
Cucumber	5
Eggplant	4
Endive	5
Kale	4
Kohlrabi	3
Leek	2
Lettuce	6
Muskmelon	5
Mustard	4
Okra	2
Onion	1
Parsley	1
Parsnip	1
Pea	3
Pepper	2
Pumpkin	4
Radish	5
Rutabaga	4
Spinach	3
Squash	4
Tomato	4
Turnip	4
Watermelon	4

A more generalized rule of thumb is: Store peppers, onions and corn for no more than two years. Beans, peas, squash and cabbage seeds remain viable for up to four years. Cucumbers, melons, and some green, leafy vegetable seeds still germinate and develop well after as long as six years of storage, according to Washington State University Extension.

Once you have decided to store seeds the NCGPR says the best way to store them is to dry seeds to about 20 % RH and store in vapor-proof containers in a cold place like a home freezer (the crisper tray of the refrigerator is the 2nd best and a cool dry place in a basement would the the 3rd best).  Those seeds left from a packet purchased at a store should be kept in these conditions until you plant the seeds, those remaining should go right back into the storage.

When saving seeds from plants grown in the garden, the following should be followed:  Always pick your most desirable, hardy and flavorful plants.  Make sure they are not hybrids or that they haven’t cross pollinated with other varieties.  You will have to decided if the time it takes to process the seeds is worth the effort especially with tomato and eggplant seeds.

Certain vegetables, such as beans, peas, peppers and tomatoes, make saving vegetable seeds simple: These have self-pollinating flowers, meaning they pollinate automatically before the flowers open.  The most difficult seeds to save include beets and carrots because they need two growing seasons to make the seeds. Use 1/2 cup dried powdered milk or silica gel with the seeds to absorb moisture. You can purchase silica gel from craft stores or the Internet.  Either of these should be left in the container that you will be used for storage for 11 days for small seeds or up to 15 days for larger seeds and then removed.  The containers, which should have airtight seals, can then be put in storage.

Peppers and tomatoes should be harvested at the point when the fruit are perfectly ripe. This means you need to know what color the final product should be: waiting for something like the Green Grape tomato to turn scarlet will mean you never save a seed, as that fruit turns a sort of gooseberry green at maturity. Pepper varieties can be even more confusing, as some will go to their graves green, while for others red or brown indicates the final stage of ripeness.

When your selected pepper reaches maturity, pick it and slice in half. Scoop out the seeds and sprinkle them out on a plate, taking care to keep them from ending up in pairs or clumps. Don’t put them on paper or a paper plate as the seed stick fast to both.  Set the plates someplace dry and somewhat cool–temperatures over about 90 degrees can kill off many seed varieties. Check them frequently, mixing them a bit to insure good air circulation. Stop the drying process when the seeds are no longer supple.

Tomato seeds are also easy to save once you do the following technique. Select, pick and slice, just as with the peppers. Then squeeze the contents of the tomato out into a bowl.  Add enough water so that the volume of the bowl increases by half again. Set this mixture aside for three days, in a place to ferment. Stir once in the morning and again at night. How quickly the top mold caused by the fermenting will develop depends on the temperature, but in a house temperature of 70 degrees three days should do it.  When the mold is clearly visible add about the same amount of water as you did three days ago. Stir well and then skim or pour off what stays on top. What floats to the bottom are the viable seeds. Rinse these seeds and then air dry them. Again, avoid extreme heat. If your seeds begin sprouting, it means the drying process has been too slow. Throw that batch away and try again. Use a screen instead of a plate, or a fan to improve air circulation. Don’t use use any added heat to try to speed things up.  This will destroy the seeds.

With eggplants, cucumbers and summer squash, wait until they are well beyond the edible stage or the seeds will be immature. The eggplants should have lost their gleam and changed their hue, the cucumbers turned soft and off-color, and the summer squash toughened.

Eggplant seeds are tiny and difficult to separated from the flesh. If you have waited long enough, the pulp can sometimes be teased away from the seeds by hand. If that doesn’t work, pulverize it with a potato masher or with a small food processor, so that the maximum number of seeds are exposed. Then, put the entire mess in a pail of tepid water and leave it there until the seeds have settled to the bottom. Skim the top off, and pour the remains through cheesecloth or a fine strainer. Sometimes you have to do several rinses to achieve a state of marginal cleanliness, but don’t feel that the final product must look as sparkling as the original seeds in the packet.

Your over-ripe cucumbers should be split in half and hollowed out. The gelatinous covering on each seed will disappear if they are soaked in warm water overnight. You can rub off any additional coating that is left in the morning.

Summer squash are treated much the same as cucumbers. All you have to do is wash the seeds enough to clean off any meaty remains or slimy remains.

The following link has several seed harvesting techniques, to include some fruits:

Saving Your Own Vegetable Seeds (PDF file) www.avrdc.org/pdf/PROD6-saving_your_own_vegetable_seeds.pdf

Leave the plates in a dry place where the temperatures will stay even and below 90 degrees. A day or two should be enough, especially if you stir the seeds a couple of time a day and/or have a fan blowing on them.  Stop when the seeds are dry, but not completely dried out.  Be sure to write the names and date of the seeds on the packets that you are storing them in.

Place the seeds in something like a baggie and then they can be layered into a plastic storage container that is suitable for the freezer or refrigerator.  Once you are ready to plant in the spring, bring them out of storage and let them get to room temperature before planting.  Plant just as you would those seeds you purchase from a store.

If you are planting seeds that are more than a year old you can test for germination (the seeds that will sprout).  Germination rates decrease when using older vegetable seeds. Test germination by pre-sprouting about 10 seeds on damp paper towels to see if at least 50 to 55 percent still germinate. If so, the seeds are still viable. If less than 85 percent sprout, sow the seeds thicker than instructed on the seed package for best results.  The general health, or vigor, is also reduced as the seeds age according to the University of Arkansas Cooperative Extension Service.  Germination rate doesn’t test for vigor and there is no test for this that home growers can use.  The following is a step by step way to test for germination.

1. Place 10 seeds on one side of a moistened paper towel (just damp, not soaking wet) and then fold the other half over the seeds.  Do this for each type of seed you are testing.
2. Place the paper towels in a zip lock bag and seal it.  Label the bag with the date and seed type.
3. Place the zip lock bag in a room where the temperature remains constant until the seeds begin to sprout, usually seven to 10 days. Parsley, carrot and celery seeds may require a longer time.
4. Conclude how viable the seeds are by counting the number of seeds that sprout. If eight to 10 seeds from the bag sprout, the seeds are viable enough to plant according to the seed coverage directions on the package. If six or seven seeds sprout, sow 25 percent more seeds than indicated on the package directions. If five seeds or less sprout, discard the seeds.

Saving your own vegetable seed is a pleasurable activity. It offers a sense of self-sufficiency and can save money. You can maintain a variety that is not available commercially or old-time varieties (heirloom), that often have disease and pest resistance or cold hardiness. Participation in a seed-saver’s exchange can also be a rewarding experience. Extra seeds may be traded for unusual types that are not available through other sources.

There are several excellent books out on the market.  The one most often recommended is “Seed to Seed,” by Suzanne Ashworth

As I was researching this subject I came across several survival seed kits.  I also found the following statement: Survival kits often cost over $100.  The same variety of heirloom seeds can be bought for around $30 if bought individually from a gardening shop or a mail order seed catalog.  Since different varieties of seeds remain viable and vigorous for different lengths of time all the seeds in the kits will need to be rotated at different time intervals.  Also, since they often come in large cans it may not be as easy to store these in the freezer or the refrigerator to maximize the storage times.  An old seed that has been stored too long will lose its vigor and will produce weaker plants.  These then will provide less produce, be more susceptible to insects and disease, if they germinate at all.

According to the NCGRP, answers to questions site:

What is the oldest living seed? The most reliable studies show some seeds in soil at archeological sites surviving for 100 to 1,700 years. (e.g. Odum 1965. Germination of ancient seeds: floristical observations and experiments with archaeological dated soil samples. Dan. Bot, Arkiv 24(2):1-70; Shen-Miller, J., Mudgett, M.B., Schopf, J.W., Clarke, S., and Berger, R. 1995. Exceptional seed longevity and robust growth: Ancient sacred lotus from China. American Journal of Botany).

Unfortunately, I was not able to access the actual article.  I don’t know if there were any seeds other than the ancient sacred lotus from China listed in the above sited article.  It is referenced by several articles just as shown above. Having done research and having published in both national and international journals, when doing a literature search, there are often articles sited that when read in the complete form aren’t properly sited and mislead and bolster statements that are incorrect. I also know there is some controversy about seeds found at archeological sites.  A USU horticultural specialist has stated that there has never been a documented source where seeds such as ancient Indian corn has been found, planted and the seed has germinated.  The only one that he knows about is a coconut that was dated to about 1,700 years old that germinated.

2 Corinthians 9:10 Now he that ministereth seed to the sower both minister bread for your food, and multiply your seed sown, and increase the fruits of your righteousness;

Next week:  When and how to start your seeds

Dennis Adamson
For The Family