Harvesting and saving native seeds expands garden

Seed saving is a centuries-old practice that allows gardeners and farmers to propagate the best plant varieties year after year. Saving and swapping seeds with a friend is a low-cost way to expand native plants in your garden, become more familiar with the peculiar traits and behaviors of these plants, obtain plants not available in a local nursery, improve the vigor of your garden and have an interesting hobby in those slow winter months.

For some longtime gardeners, saving seeds from their plants may be a family tradition. New gardeners, often wonder if they can save the seeds from this year’s vegetables and flowers in order to grow next year’s garden. The answer is yes, but it is necessary to plan ahead.

Seed saving involves the careful selection and harvesting of seeds from healthy and productive plants.

Know your plants

Knowing your plant’s specific scientific name (genus and species) is important as common names tend to be regional. “Straight species” refers to plants that have occurred naturally and have not been cross bred to create cultivars.

Cultivars are created by crossing plants of two different species to maximize certain traits usually to make them more marketable for retail gardens. Seeds saved from cultivars may not produce offspring with the same traits as the parent plant. They often revert to one of the original parental species.

Harvesting

Timing is critical when harvesting seeds. The plant’s seeds must be allowed to mature naturally. Harvest too early and the seed will not have stored energy to survive germination. Harvest too late and either the seeds rot or you have lost them to the birds or the wind.

The plants will give clues when they are ready. Look for faded, dry flowers over the entire flower stalk or cones that have shed all their petals. Pods should be brown and dried. Covering the flower heads with a paper or cloth bag to keep birds and insects from consuming the seeds may be necessary. Once the flower head is brown, it can be cut off to dry upside down in a paper bag in a warm, dry space.

Preserving

The key to successful seed saving is to select only the largest, most perfect seeds, and to properly clean and store them in a low moisture, low temperature environment. If the seed head or pod is damp, dry the seed before extraction; this can take up to six weeks.

Then, extract the seeds by either breaking the seed head/pod apart, shaking it in a bag or rubbing it on a screen. The methods depend on the size of the seed, its fragility and formation.

Next, lay the seed flat on paper or a screen to dry further. Drying temperatures should never exceed 100 degrees. Clean the seeds of debris, which can harbor insects, disease, mites or fungus. Finally, package, label and store the seeds. The label should include the plant genus and species, location harvested, and date. Many seeds are viable for only a few years, which makes the date of harvest important. Some seeds need to be planted when they are fresh and should not be stored for the winter.

Moisture is Your Enemy

At this stage, the seeds are alive but in a dormant state and you want them to remain that way until germination. Optimum moisture content for native plants is to 10 to 15%. This can be attained by drying the seeds and then packing them in a sealed container with silica gel packets, white rice or powdered dry milk in the bottom. As long as seeds are kept in a cool, dry, dark place, they can be stored in plastic or glassine bags, plastic containers or glass jars.

Storage temperature also affects the quality of the seeds. Some seed savers have luck storing seeds in a refrigerator. Thirty-five to 37 degrees are the best options for a home gardener. Seeds should not be stored in a freezer as most home gardeners cannot reduce the moisture enough to prevent cracking of the seed coat.

Saving seeds from favorite plants requires trial and error. With experience, you will be able to determine which seeds are worth saving.

To learn more on this subject, sign up for the workshop on Oct. 17, where Judy Pfister will demonstrate when a seed is ready to be harvested; how to extract and clean the seeds; how to test for viability; and seed drying techniques for a variety of native plants.

The workshop will be held at the Cooperative Extension Services office at 16483 County Seat Highway on U.S. 9, west of Georgetown. To register, email kjscott@udel.edu or call 302-856-7303. Weather allowing, participants will go into the demonstration garden to harvest some seeds to take home.

For information about other Master Gardener workshops, visit udel.edu/master-gardeners and click on Garden Workshops. For questions on this subject or any gardening topic, call the Master Gardener Helpline.

In New Castle County, 302-831-8862; in Kent County, 302-730-4000; and in Sussex County, 302-831-3389. The Master Gardeners monitor the helpline in the winter but it may take a few days to get back to you.