We’re fortunate to live in a time when we can just head to the garden center to pick up a wide selection of seeds. It sure makes gardening a whole lot easier! Nevertheless, it’s extremely gratifying to save your own seed, just as our farming and gardening ancestors did for centuries.

Seed and chaff

Seed and chaff must be separated in the dry seed cleaning process.

Photo Credit: Scott Vlaun, courtesy Seeds of Change

Screening lettuce

Mesh screens work well to clean dry seeds.

Photo Credit: Scott Vlaun, courtesy Seeds of Change

Winnowing beans

These Jacob’s cattle beans are being separated from the chaff in a process called winnowing.

Photo Credit: Scott Vlaun, courtesy Seeds of Change

Ancient bean variety

Seeds can last a long time. In fact, the Science Museum of Minnesota has germinated ancient seeds from an archeological dig and successfully grown plant varieties that Native Americans cultivated hundreds of years ago!

Photo Credit: Mark A. Miller

There’s a natural rhythm to the cycles of nature. As gardeners, we become attuned to that rhythm when we sow the seed, nurture the plant, harvest the fruit or flower, and finally return the seed from the fruit to the earth again. These days, few of us bother with saving seed. But as interest in sustainability grows, there’s more reason than ever to start gathering seeds.

Of course, we need to know some plant reproduction basics first: Some plants produce “perfect flowers” (also called bisexual) that are self-pollinating. This means they contain both male and female parts and don’t require the help of insects or wind to reproduce. These plants don’t usually cross-pollinate with other varieties, so we’re safe planting them close together in the garden. Some examples include legumes, tomatoes, some varieties of grapes and lettuce.

On the other end of the spectrum are the imperfect-flowing plants. Male and female flowers are found separately on the same plant, and they require a carrier (such as the wind, bees or other creatures) to transport pollen from the male to female flower. Plants within the same species can crossbreed when pollen is carried from one plant to another: Picture a robust cabbage crossbreeding with a sickly specimen. The resulting seeds would likely convey the undesirable traits. As a general rule, plants should be 500 feet from each other to prevent cross-pollination.

Another way to ensure good seed is to stagger plantings. For example, plant and harvest a short-season crop before planting a later-season crop of the same genus. Because most vegetables have imperfect flowers, that means staggering your food crops like cole (cabbage, broccoli, greens), carrots, beets, chilies, herbs (parsley and basil), onions, corn and radishes.

We also need to learn a little something about harvesting seed. Methods vary from plant to plant, so we have to familiarize ourselves with the signs of seed maturity for each. Some plants have exposed seeds that emerge as flowers fade and petals fall. Others have seed that may be contained in fruit or on stalks. Generally speaking, seeds should be picked before the first frost. They also shouldn’t be allowed to fall to the ground or be damaged by adverse weather conditions.

Once seeds are ready to harvest, it’s time to gather and clean them (to protect their viability). Although we can buy commercial products to facilitate seed cleaning, there are probably adequate materials in the garden shed or garage to do the job (whether it’s the wet or dry seed-cleaning process).

Wet Cleaning Process

Seeds with pulp or a gelatinous substance surrounding them require cleaning and drying. Allow the seeds to set for at least 24 hours to allow fermentation to kill any pathogens. Afterward, immerse the seeds in water. Stir vigorously. Viable seeds will sink, while hollow ones (as well as the pulp) will float. (Some seeds may take 3-4 days to loosen their pulp.) Skim the floaters. Pour into a strainer, and turn on running water to clean them.

Once the wet seeds are clean, they can be dried. Most ceramic, wood or (the best choice of all) metal screen surfaces are fine. (Flimsy plastic, fabric or paper isn’t recommended for drying because the seeds may stick.) Spread your seeds out so they’re not clumped, and stir them now and then. Good circulation will help facilitate the drying process, so consider turning on a nearby ceiling fan or setting your drying seeds in front of a breezy window.

Dry cleaning process

For other seeds, the dry cleaning process works best. First, separate the seeds from the chaff: Construct a frame around ¼-inch mesh for the first stage of threshing or winnowing (as this process is called). Push the seeds through a succession of frames with ever-tighter mesh screens until most of the seeds are separated from the chaff. Other methods include handpicking chaff from the seeds or turning a fan on heavier seeds to blow the chaff away.

Once your seeds are clean and dry, store them in labeled paper bags or airtight plastic containers. Be sure to keep them away from sunlight and in a cool place. I live in a cool, dry climate, and have had success with planting some very elderly seeds (10 years old) that were stored in paper bags, but some experts recommend plastic containers as a way to prevent mold. Obviously, the older the seed, the less viable it’s going to be. Seed life does vary according to species, but generally most food-producing seeds are good 2-5 years after they’re harvested.