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TCCL Seed Library: Seed Saving and Care

An open and circulating collection of heirloom garden seeds

Seed Saving Basics


1.      Grow your garden.

2.      Choose the best plants—strongest, tastiest, prettiest or most productive—and let them go to seed and ripen fully. 

3.      Wet-process seeds from wet fruits, like tomatoes, by soaking the seedy pulp 2-3 days in a jar of water, then rinsing.

4.      Dry all seeds completely.

5.      Store in a container and label.

6.      Fill out the return form on the first page of this guide..

7.      Return to the library for others and choose your next batch of seeds.

Isolation Techniques

To make sure the seeds you save are the same variety as their parents takes isolation techniques.  

Distance:  Many easy seeds need just a little distance, 25-50 feet,  from other varieties of the same plant to make "true" seed.

Time:  Some advanced seeds, especially wind pollinated plants, can be isolated just by saving seed pollinated earlier or later than other varieties.

Barriers:  In the home garden, it may be easier to hand pollinate a squash flower and close it to other pollinators than to find 500 feet of isolation.

The library has several good books explaining seed saving.  

The Seed Ambassadors have published an in-depth, free on-line booklet on seed-saving.  

Seed Matters has published a handy on-line chart of isolation distances.

Pollination and Isolation

Plants are divided into families and just a few major families make up our common gardens.  If you know the family of a plant, you can make a good guess whether it self-pollinates or cross-pollinates, and so how much isolation you need to give it to get true seed.  Here are some of the most commonly found, in order of ease for seed-savers:

Legumes: Beans and peas.  Self-pollinating, require minimal isolation distance.

Compositae: Lettuce, sunflower, salisify, chickory, endive.  Both self- and cross-pollinate, may require some isolation. 

Solanaceae: Tomatoes and peppers.  Usually self-pollinating,  though peppers require more isolation distance.

Amarylliaceae: Leeks, onions and chives.  Some cross-pollination, requires some isolation.

Umbelliferae: Carrots, dill, fennel, celery, parsnip, parsley.   Cross-pollinate within species, isolation required.

Brassicas: Cabbage, broccoli, kale, cauliflower, mustards, radish.  Cross-pollinate freely across species, require careful isolation techniques.

Chenopodiaceae: Beet, chard, spinach, lambsquarters, quinoa.  Wind-pollinated and cross-pollinate very freely, require mechanical isolation (bagging).

Curcurbits: Squashes and melons.  Cross-pollinate within species freely, across species occasionally,  require careful isolation techniques.




Seed Processing

  • Dry seed processing:  seed that dries down on the plant and needs to be kept dry until it is sown. The steps involved are harvesting (usually cutting the seed stalk off of the plant), threshing (separating the seed from the stalk and chaff) and winnowing (removing the seed from the chaff using a breeze). Dry seed processing is used for grains, lettuce, brassicas, onions, beets, carrots, celery, cilantro, and chicories, among others.


  • Wet seed processing:  many garden fruits. This includes melons, peppers, eggplant, tomatillo, and squash seed.Wet seed processing involves removing the seed from the fruit, rinsing clean of debris, and then drying. A jar of water can be used to separate seed from debris -- seeds sink and debris usually floats. Drying the seed quickly and completely after wet processing is very important.


  • Fermentation seed processing: Similar to wet seed processing, but the seeds and their juices (as in tomato and sometimes melons and cucumbers) are mixed with a little water and allowed to ferment for a day or few. The fermentation process breaks down germination inhibitors such as the gel-sack that surrounds tomato seeds. When a layer of mold has formed on top of the water and the seeds sink, the fermentation is complete. You simply need to add more water, swish it around, then decant the mold and pulp. You may need to repeat this process several times, as the good seeds sink to the bottom and the scum floats off the top. After all of the pulp, bad seeds, and mold is removed, drain the water from the seeds and set them out on a plate, screen, or paper towel to dry. Once the seeds are thoroughly dry, place them in a moisture-proof container, label and store them for the future.

Taste, Memory  The Organic Seed Grower Gathering

Care and Keeping of Seeds

Seeds, kept under ideal conditions, can remain viable several years, even centuries.  But without care, they start losing germination rates within a year.  Handle seeds gently.  Dropping and rough handling can reduce germination rates.

Seeds like to be

  • Dry
  • Cool
  • Dark
  • Stable

Collect seeds in dry weather and dry further indoors, in a brown paper bag or on a cookie sheet, if necessary before storing.

Label seeds carefully.  

Many people store seeds in sealed containers in the refrigerator, where it's dark and the temperature is constantly low.  

Science for Seed Savers

Garden Organic produced this Basic Botany for seed Savers Guide.  

The International Seed Saving Institute has an on-line guide of seed-saving detail, plant by plant.