Saving Open Pollinated Seeds

Article #2: Saving Open-Pollinated Seeds by Margaret Flynn

One of the first things to remember when saving seeds is never plant all your seed from one stock. Always save some in case anything should happen to your crop.

You need to be aware that cross-pollination of seeds can occur from other vegetables in the same family, or from other gardens within about 1/4 mile.

It’s best not to save seed from just our largest tomato, for example, but to save seed from the smallest, largest, earliest and latest fruits. Equal amounts of these four types of seeds should be mixed. In this way we will have a much greater genetic diversity in our seed samples. We should look at the whole plant too, not just the fruit. Select several plants to save seed from, those with characteristics you want for your next year’s plants: size, flavor, earliness, ability to survive a short season (where applicable), disease-resistance, drought-resistance, insect-resistance, lateness to bolt, trueness to type, color, shape, thickness of flesh, hardiness and storability. All these factors can and should be selected for.

Temperature and moisture extremes, especially in combination, can cause damage to seeds before harvest. For example: an early sustained freeze while the seeds still have a high moisture content. It is best to have dry weather before and during harvest, so that the seeds can dry on the plant and remain dry.

Drying Seeds

When drying and storing your seed, you want its vigor to stay as high as possible so that seeds will germinate rapidly with good disease-resistance. Vigor is destroyed by high temperature and high moisture during storage. Seeds can be dried on a screen or on wax paper in the sun, by sealing them in an airtight container with silica gel (until they reach the proper moisture levels for entry into storage), or by putting them in your oven with the pilot light on and the door cracked.

(WARNING: Damage to seeds will begin at temperatures of 96° F or more. Even at the very lowest setting, an oven temperature can vary enough to damage your seeds.)

Seeds must be completely dry before you store them and they should break instead of bending (less than 8% moisture). Store seeds in a completely airtight container at as low and constant a temperature as possible. Put each variety of seed in an envelope and write the name and year on each one. Put these envelopes into any glass jar that has a rubber gasket lid that can be screwed down tight enough to make the container airtight and moisture-proof. Homemade gaskets can be cut from old inner tubes.

Adjustable channel-lock pliers can be used to screw the lids on as tight as possible. Black electrical tape can be used to seal questionable lids.

Another possible container is a flat bag that has laminated walls of paper/foil/plastic. It can be sealed with a Seal-A-Meal, or sealed with an iron set on “wool” applied to the open end of the bag for three seconds. (The sealed edge can later be cut off and the bags reused.) They can be put directly into the freezer and take up less space than jars; they are also inexpensive.

Your containers can be kept in a freezer with no damage to the dry seeds. The next best place is a refrigerator, and the next is any cool area where the temperature will remain as constant as possible. When you take the container out of the freezer, you must let it sit out overnight to come to room temperature before you open it. If you don’t, moisture will condense on the cold seeds and your effort to dry them will have been wasted. Do not leave the container open for any length of time, and don’t go into it too often because temperature fluctuation is not good for the seeds. If you store your
seeds by this method, they will hold their vigor for up to five times the period shown on viability charts.

We discussed reasons for saving nonhybrid, open-pollinated seeds, what to consider when choosing plants for saving seeds, and how to dry them. Let’s look at some more detailed information on specific vegetables.

Beans

Phaseolus vulgaris contains common bush or pole beans, whether used for green snaps, green shell or dry. They are self-pollinating before the flower opens, so there is very seldom crossing. Sometimes you’ll notice variation or oddities in the seed that may be due to a genetically unstable variety or a difference in conditions such as a change of soil pH or wetness at harvest rather than to any true crosses. You can plant varieties of Phaseolus vulgaris side by side.

Phaseolus coccineus are “runner beans.” You can tell these when they come up because they develop with their two seed halves under the ground. Their flowers are self-pollinating, but bees or bumble bees and hummingbirds work them heavily and thus cross them. You should either grow only one variety of runner beans or separate two of them by at least the length of your garden.

Mark a few of your best plants, and let the pods dry out completely on the plant, weather permitting. When most of the leaves have fallen off, pull the plants and hang them under cover to finish drying. Small amounts of seed can be shelled by hand; for large quantities, make sure beans are thoroughly dry, crush or thresh pods, separate the beans from the chaff by winnowing in the wind; label, and store.

Weevil eggs are almost always present under the bean’s seedcoat and can ruin your seed in a few months. They can be killed by placing the thoroughly dry beans in a tightly-sealed jar and freezing them for at least a day.

Broccoli

Broccoli produces seed its first season (unlike the other biennial members of the cabbage family) if you sow it early enough that plants are quite large by the long days of summer. However, it crosses readily with cabbage, kale, brussel sprouts, cauliflower, or kohlrabi, if any of these are flowering within 1/4 mile. Don’t cut flower heads for food that you are saving seed from.

Chinese Cabbage

Brassica pekinensis is a cross-pollinating annual. It will not cross with any of the cabbage family, but will cross easily with other varieties of Chinese cabbage. It sends up a seed stalk which forms a pod that will turn brown when mature. If you plant more than one variety of Chinese cabbage, the isolation distance is 1/4 mile. The rest of the method is the same as with lettuce.

Corn

Corn is wind-pollinated, so any corn (sweet, popcorn, ornamental, dent, flint, etc.) will cross very easily with other corn. To keep corn “pure,” you must grow it 1/4 mile from any other corn, or hand-pollinate it. Corn is very “plastic,” so by observing and selecting carefully you can gradually determine characteristics your future crops will have. Let ears you are saving seed from ripen on the stalk until husks are dry, pick them, pull husks back, tie several husks together by the husks, hang in a dry, well-ventilated place until completely dry, shell, save only completely-formed kernels, and store. (An early and late variety can be planted side by side if the early one stops pollinating before the silks of the late one begin to emerge.)

Cucumbers And Cantaloupes (Muskmelons) And Watermelons

These all belong to different species and will not cross with each other (bug gherkins cross with cukes, muskmelon with casaba, and watermelon with citron). They are all insect-pollinated, so different varieties of each of the three will cross easily among themselves. If you are going to save seed, grow one variety of each. (Remember that with vine crops and any other vegetable that crosses very easily, that if you have any neighbors within 1/4 mile who are also growing that vegetable, you would be wise to try to supply them with your seed.)

Let a few of the earliest maturing well-formed fruit become completely ripe (cukes turn golden yellow, muskmelons crack at the stem, watermelons have a deep hollow sound when thumped). This ruins cukes for eating, but with watermelon and cantaloupe, the seeds are mature when they are ready to eat. Scoop out the seeds, wash them gently to remove pulp (a sieve may be used), and let them dry .totally on a piece of foil. Keep them separated and stir them occasionally so they don’t stick together. When completely dry, label and store. (Remember, seeds are dry when they break instead of bending.)

Eggplant

Pollination is like peppers, so separate varieties by the length of your garden or with a tall crop. Leave the best fruits on several of your plants for as long as possible, and when fully mature, scrape out seeds, separate from the pulp, dry and store.

Gourds

Legenaria siceraria are hard-shelled bottle gourds with evening-blooming white flowers. They don’t cross with vegetables in the squash section, edible varieties include: Cucuzzi (also called Italian Edible Gourd and Italian Climbing Gourd) and Guinea Bean Gourd (also called New Guinea Bean and New Guinea Buttervine). Saving seeds of squash, pumpkins and gourds is the same as with cucumbers (except that summer squash varieties must be left on the vine much later than the eating stage, until the shell is quite hard).

Lettuce

Lettuce is self-pollinating with little chance of crossing. Select several of the firmest heads or best leafy plants which are slowest to bolt (send up their seed stalks). When seed is fully developed, pull plants and hang them under cover to finish drying. Crush pods, separate seeds, label and store.

Okra

Okra is self-pollinating, so you can grow more than one variety with little separation. Leave at least two of your best plants completely alone. When pods are dry, but before they open enough to drop seeds on the ground, shell them and save.

Peas

Peas are self-pollinating, but cross slightly more easily than beans. So if you grow two varieties, separate them by the length of your garden or with a tall crop. Everything else is the same as with beans.

Peppers

Peppers are mainly self-pollinating, but insects may cause some crossing in varieties planted closer than 1/8 mile. When growing more than one variety of peppers (or if sweet and hot), separate them by the length of your garden or with a tall crop to keep them from crossing (and sweet peppers from becoming hot). Select several of your largest and best peppers from your best plants. Let them ripen on the plant until red and starting to soften, scrape out seeds, dry and save.

Potato

Potato varieties don’t cross since tuber divisions are really just clones. Crossing between potato flowers affects seed balls, not the roots. Select a few of your best-looking plants that are surrounded by healthy plants to save for seed. Never keep potatoes for seed that show any sign of  scab. You might be able to increase your production by planting small (egg-sized) whole potatoes, since they are less apt to be badly sprouted and often produce a vigorous plant more quickly than cut potatoes. If planting small whole sprouted potatoes in spring, don’t damage the big sprout on the eye end of the potato since this will produce the most vigorous plant. You can just break most of the other sprouts off. Some people think that yields are improved by planting sprouted potatoes. Plants sometimes emerge in just a few days (sometimes two weeks) ahead of nonsprouted potatoes. Dig potatoes when the vines begin to dry up— when the soil loses its shade, it gets hot and your crop may be damaged. Washing/not washing doesn’t seem to affect how well your potatoes keep. After drying in the shade for only a few hours to toughen their skins, they are ready to store, the colder the storage temperature the better (34°-40°F). It’s been said that burying them in dry sand is the perfect way to store them.

Pumpkins And Squash

These are insect-pollinated and cross very easily. All pumpkins and squash belong to one of four species of the genus Cucurbita, so when saving seeds, plant only one variety of each of the following species:

Curcubita Pepo includes summer squash, all true pumpkins, varieties that are both bush and long-vined; stem and branches both have five sides and spines. Includes all acorn squash (Des Moines, Ebony, Ebony Bush, Jersey Golden, Royal, Table King, Table King Bush, Table Queen, Table Queen Bush, Table Queen Ebony, Table Queen Mammoth), Black Beauty, Casserta, Cheyenne, Chiefinei, Cinderella. Includes all of the cocozelles (Green, Vining), Connecticut Field, Cozini. Includes all of the crooknecks (Dwarf Summer, Early Summer Golden, Early Summer Yellow, Golden, White Summer), Crystal Bell, Delicata. Early Cheyenne Pie, Fordhook, Fordhook Bush, Fort Berthold, Golden Centenial, Golden Custard, Golden Oblong, Hyuga Black, Jack O’Lantern, Kikuza White, Lady Godiva, Little Boo, Lunghissimo Bianco Di Palermo, Mammoth Gold. Includes all the marrows (Boston, English Vegetable, Green Bush Improved, Long White, Vegetable, White Bush, White Vining Vegetable), Naked Seeded, New England Pie Pumpkin, Omaha, Panama, Perfect Gem, Pie Pumpkin, Royal Bush. Includes all the scallops (Benning’s Green Tint, Early White Bush, Early Yellow Bush, Long Is. White Bush, Mammoth White Bush, Patty Pan, St. Pat, Summer Bush, Yellow Golden), Small Sugar Pumpkin, Spaghetti Squash, Spookie, Stickler, Straightneck, Early Prolific, Streaker, Sugar Pie, Sweet Dumpling (Vegetable Gourd), Table Gold, Thomas Halloween, Tricky Jack, Triple Treat, Uconn, Winter Luxury, Winter Nut, Youngs Beauty, Vegetable Spaghetti. Includes all zucchinis (Black, Burpee’s Fordhook, Burpee’s Golden, Dark Green, Gold Rush, Gray), and any of the small Hard-shelled, Striped and Warted Gourds.

Cucurbita maxima have very long vines and huge leaves, stem is soft, round and hairy. Alligator, Arikara, Atlas, All banana squash (Blue, Giant, Orange, Pink, Pink Jumbo), Bay State, Big Max, Big Moon. All buttercups: Blue, Bush. All delicious: (Golden, Green), Emerald, Essex, Estampes, Gilmore, Gold Nugget, Greengold, Guatemala Blue, Hokkaido Green, Hokkaido Orange. All hubbards (Baby, Baby Blue, Chicago, Chicago Warted, Warted Green, Warted Improved), Hungarian Mammoth, Hungarian Mammoth (Cornell Strain), Ironclad, Kindred, King of Giants, King of Mammoths, Kuri Blue, Kuri Red, Mammoth Chili, Mammoth King, Mammoth Whale, Mammoth (Genuine), Marblehead. All marrows: (Autumnal, Boston, Orange, Prolific), Plymouth Rock, Rainbow, Red Estampes, Show King, Sibley, Silver Bell, Sweetmeat, Tuckernuck. All turbans (American, Golden, Turks), Victor Watten, Winnebago, Yakima Marblehead.

Cucurbita Moschata has large leaves and spreading vines, and a smooth five-sided stem which flares out as it joins the fruit. African Bell, Zizu Gokwuase, Alagold, Butter-bush. All butternuts (Baby, Early, Eastern, Hercules, Ponca, Puritan, Waltham, Western), Calabaza (Cuban Squash), Calhoun, Cangold. All cheese (Large, Long Island), Fortuna, Futtsu Kurokawa, Golden Cushaw, Hercules, Kentucky Field, Melon Squash (Tahitian), Patriot, Peraora, Ponca, Tahitian (Melon Squash), Virginia Mammoth, Wisconsin Canner.

Cucurbita mixta was formerly included with C. moschata and has similar characteristics. Chirimen, the Cushaws (except Golden Cushaw which is C. moschata), (Green Striped, Solid Green and White), Japanese Pie, Mixta Gold, Tennessee Sweet Potato.

Varieties within a species (one of the four groups) cross very easily, but don’t worry about crossing between species. Crosses between different species are hard to make and their progeny are so highly sterile, that crosses by natural means are unlikely to cause concern. You do need to consider pollen from neighbors’ gardens contaminating your efforts at keeping pure seed strains, if they are within 1/4 mile. Otherwise you can use these lists to keep four varieties of, pumpkins/squashes pure (one from each species). If your aim is purity (and/or if you are sending seeds to the Seed Savers Exchange) and you do have close neighbors, you need to hand-pollinate. Otherwise you could lose in one season what someone else has spent a lifetime of gardening to develop or preserve. (If you are afraid that a squash you are growing might have crossed, remember you won’t see the variation in that summer’s fruit. Grow it again to check it. If it has crossed, you’ll see the variation when you grow the seed from the fruit that crossed.)

In an experiment to determine at what point there was the greatest number of fertile squash seeds, they found it to be 20 days after the fruit is fully mature—a 20-day after-ripening period when the seed actually improves in the fruit after you pick it.

Radishes

Radishes are insect-pollinated, so grow only one variety. Choose several of the largest, earliest roots to save seed from. The seed pod on the seed stalk will turn brown at maturity. At that point, pull the plants and finish drying under cover.

Spinach

Spinach cross-pollinates and has very fine pollen that is carried long distances by the wind. It only crosses with other varieties of spinach, very easily. Plant one variety only for purity in seed strains. Save seed as with lettuce.

Sunflowers

Sunflowers cross easily with wild sunflowers, making them unsuitable to save for seed. Some people call this home-saved seed that is “running out”—seed doesn’t really run out, but if you don’t take the right precautions, a gradual process of undesirable crossing over several generations can make the seed of some vegetable varieties practically worthless.

Tomatoes

Tomatoes are over 98% self-pollinating, but even such a slight amount of insect pollination over a number of seasons may be enough to destroy the characteristics that made the variety unique. Don’t grow tomato varieties side by side if you want to save seed from them. Remember, don’t just save seed from your largest tomato. For better genetic diversity, save seed from the smallest, largest, earliest and latest fruits. (This would only be twice the work if you saved seed from the earliest and also a large fruit at the beginning of the season, and the latest and also a small fruit near the end of the season). Mix equal amounts of these four seeds.

Select well-formed fruits from a few of your best plants and let them ripen on the plant beyond the edible stage until they are getting soft, but not to the point where they are going bad. Squeeze seed from several fruits into a glass, add some water, let the mixture ferment at room temperature for several days, stirring vigorously several times daily. After a couple of days the good seed will be on the bottom and bad seed and pulp will float on the top and can be washed away. This fermentation is said to kill several seed-borne diseases (many people use this method to separate seeds from pulp whenever seeds are embedded in soft fruit). If you don’t want to use this process, squirt the seeds into a sieve and rub them with your fingers against the sieve under running water. Pick out or work all the pulp through the sieve and keep working seeds until the whole batch is really clean. Then spread them thinly and separately on wax paper. When they are completely dry, label and store.

All of the above vegetables are annuals, which grow and develop seed in one season. Biennials don’t produce seed until the end of their second growing season. Biennials are: the root vegetables (carrots, onions, leeks, parsnips, rutabagas, salsify, beets, turnips, celeriac and winter storage-type radishes), the cabbage family (cabbage, broccoli, brussel sprouts, cauliflower, and kohlrabi), parsley, celery, kale (or borecole), collards, endive and Swiss chard. All these vegetables (except salsify and endive) are cross-pollinated, so to save seed and keep it pure, grow only one variety of each and only one member of the cabbage family, since they all cross. Select good-sized roots or firm heads to save seed from, dig them before frost, keep them in cool storage over the winter, replant them the following spring and they will bear seed that summer. If your climate isn’t really severe (or with hardy roots like turnips and rutabagas) you may be able to just mulch them heavily over the winter, take the mulch off early in the spring and let them go to seed. Carrots will cross with wild carrots (Queen Ann’s lace) if your garden is surrounded by meadow. Swiss chard, beets, mangels and sugar beets all cross. Celery and celeriac cross. Turnips and beets and broccoli will behave as either an annual or biennial depending on the climate they are grown in.

Hot Water Treatment of Seeds

This is a method for controlling the seed-born phase of diseases such as black rot and black leg in the cabbage family, bacterial canker and target spot in tomatoes, and Septoria spot in celery. You’ll need an accurate thermometer, electric fry pan, large sauce pan, kitchen sieve and paper towels. Try a practice run without the seeds. Heat some water to 50°C. Pour a little into the warm electric fry pan, fill the sauce pan 2/3 full and set it in the fry pan. Regulate the temperature either by late the temperature either by turning up the fry pan or taking the sauce pan out of the fry pan. When you can maintain 50°C, pour in the seeds, stir until they are all wetted and not floating, then stir gently throughout the whole process. Treat broccoli and Brussel sprout seed for 20 minutes at 50°C, cabbage for 30 minutes at 52°C, cauliflower for 25 minutes at 52°C, celery and pepper seeds for 30 minutes at 50° C, and tomato for 25 minutes at 55°C. Then sieve the seed and spread it on paper towels away from direct sunlight, dry and store them.

Germination Testing

If you want to test the viability of your seeds, especially if you intend to exchange them with the Seed Savers Exchange (in fairness to fellow members), you can take 10, 25, 50 or 100 seeds for each variety, roll in a damp paper towel, put in a plastic bag, and put it in a warm spot. Count the sprouts after 7-10 days. Seven sprouts per 10 seeds is 70% germination, etc. The idea is to be sure that at least some of your seed will sprout; it’s better to find out you have more to learn about saving seed than to have you or an exchange member waiting next spring for your seed to come up.

Cleaning Seed

Seeds that are harvested wet can be cleaned by floating off the light (and weak) seeds, hollow hulls and other debris. This works well for tomatoes (after fermentation), peppers, eggplant, melons and squash. Remove seeds from fruit, ferment if required, add water and stir vigorously. Good seeds are heaviest and sink; the rest of the debris floats and can be poured off. Repeat this four or five times or until the water poured off is free of debris. Rub wet seed over a sieve to remove attached pulp, rinse again, and dry.

Seeds that are harvested dry should be rubbed and winnowed to remove chaff.

Isolation and Purity

We have used isolation and planting only one variety of cross-pollinating crops to maintain pure strains, but it should be noted that even self-pollinated plants may cross if conditions are just right. If your aim is absolute purity and you are saving seed from more than one variety of a self-pollinating crop, separate varieties by at least a row or two of another crop.

Thanks for saving seeds!