Vegetable Seed Saving Handbook
Amaranth is self-pollinating, but will also cross-pollinate (possibly even between different species). Further, wild amaranths are common in most areas worldwide. Individual heads can be bagged to allow growing several varieties in proximity or to ensure that wild plants don't cross the plants you're growing. From ½ mile (green amaranths) to two miles (grain amaranths) are needed for reliable distance isolation.
Grain amaranths may need support to keep the plants from falling over as they mature because of their large, heavy seed heads. Collect the seed heads as they dry on the plants and store in closed paper bags to finish drying (many of the seeds will shed naturally). Don't let the seed heads get wet after they dry. Chaff easily blows away after seed heads are crumbled—watch for thorns or prickles in some plants!
If germination is slow, lightly stir the soil's surface... amaranth seeds need some sunlight after a period of darkness to germinate. This trait adapts them to disturbed or overturned soil, hence one of their common names, "pigweed," so-called because they would germinate in hordes in an area after pigs had passed and turned the soil, exposing their seeds to the light so they could germinate.
Cut seed heads when they are becoming dry and hang them upside-down in large paper bags or over tarps to collect the tiny seeds. The dried heads can easily be crumbled in the hands and the chaff gently blown away if you're in a hurry.
Amaranth seeds can last for many years if properly stored, and can sprout in the garden even after several years in the soil.
Arugula is self-sterile—insects must be able to reach the flowers of different plants for pollination to occur. Different varieties of arugula will cross each other and must be separated by ½ mile for safe distance isolation. Arugula will not cross other members of the Cabbage Family.
To save seeds from arugula, leave plants in the ground to overwinter after harvesting leaves for eating during the growing season. As with any member of the Cabbage Family, allow seeds to ripen and dry on the plant in the spring—but do not leave for long after they are dry or the pods will shatter and the seeds disperse—arugula pods are thin-walled, and shatter quickly after drying.
This trait of readily throwing seed suggests that arugula may be recently domesticated, since long-domesticated plants tend to hold their seeds for a longer time after maturing Seeds from plants that release their seeds early failed to be collected and replanted when agriculture started, thus genetically favoring those plants which hold onto their seeds for a longer time after maturing.
Arugula seeds will last for 4 or more years if properly stored. See also Cabbage Family.
Basil relies on insects for pollination, but can be reliably isolated by as little as 150 feet since most of the pollinating insects are small and don't travel far. Different basil varieties will cross each other.
Harvest seed heads as they dry and allow to finish drying in a warm, dry spot. Seeds are easily removed by crumbling the dried flower heads and then blowing away the chaff. You can practice over a plastic sheet at first until you get the hang of it.
Plants cut back after harvest will grow another set of leaves for harvest—and even produce seeds again—if your season is long and hot. A branch or two of each plant can easily be left to go to seed while collecting leaves for cooking with from the rest of the plant.
Basil seeds will last up to 5 years if properly stored.
Beans are self-pollinated, and different bean varieties do not commonly cross-pollinate each other. Similarly colored varieties should be separated by enough distance to keep the vines from intertwining, to make them easy to distinguish at harvest. Allow pods to dry on the vines before picking and shelling, then finish drying the beans in a dry spot.
If you're eating your beans green, allow just one or two pods per plant to remain and mature for seed... too many pods maturing on an individual plant will cause it to stop setting more beans and concentrate on maturing the ones it has.
Pick beans for seed after the pods are ripe and have dried on the plants. Don't allow dried pods to get rained on as the beans may quickly mildew or sprout in their pods. When very dry many pods will split on their own to drop their seeds; the rest can be easily crumbled in the hands and the finer chaff blown away after removing the big pieces. Finish drying the beans in a dry spot indoors or under cover.
Bean seeds, properly dried and stored, will keep for 4 years. See also Bean Family.
Members of the Bean Family are self-pollinating and crossing is uncommon, but rare varieties can be separated by 100 feet to insure purity.
In most cases, saving bean seeds is as simple as waiting for the pods to dry on the vine, collecting the seeds, and completely drying them before storing in jars. Separate different bean plantings by enough distance to avoid having their vines intertwine, however, or harvesting can become troublesome with similarly-colored varieties.
A danger with members of the Bean Family is late summer rains, which can moisten seeds drying in their pods while still on the vine. Too much moisture during seed maturation lowers the viability and storage life of the finished seeds, and can even cause them to sprout or mildew while still on the vine. Pick mature, dry pods every day or two and don't save seeds which have been wetted by rains.
Bean and cowpea seeds, properly dried and stored, will keep for 4 years.
The Bean Family includes the following species:
Beets and Swiss chard will cross-pollinate, as they are from the same species. Beets/chard must be separated by wind-proof caging, bagging or up to 2 to 5 miles of distance to ensure purity as their wind-blown pollen is exceedingly small and light.
It's easy to leave the base and center of chard plants to over-winter, flower and produce seeds while still eating plenty of leaves. However, to save seed from beets you'll have to plant 20 to 30 plants to leave in the ground to over-winter if you want to get seeds (use a deep straw mulch to help in colder zones). You can harvest tasty beet greens for the first part of the season, and you can crowd the plants a bit. You don't have to pamper them with lots of room, water and fertilizers to get plenty of seeds in the spring—just make sure they're big enough to get through the winter and re-sprout.
Allow beet seeds to fully mature and become dry on the plants before harvesting. After final drying the seeds can be easily rubbed off the stems. Beet seeds will last for up to 5 years if properly stored. See also Beet Family.
Wind-pollinated members of the Beet Family have very light pollen and need up to 2 to 5 miles for safe distance isolation. Chard and beets are in the same species (Betula vulgaris) and must be isolated from each other or they will cross. Different Beet Family species will not cross-pollinate, so that one beet or chard, one quinoa (Chenopodium quinoa), one red (Chenopodium giganteum) and one white (C. alba) lamb's quarters, one orach (Atriplex hortensis) and one spinach (Spinacia oleracea) can all be grown together without danger of crossing.
You can bag or cage varieties of the same species for isolation, but techniques vary depending on whether the species will self-pollinate or not. Quinoa and lamb's quarters are self-pollinating, so large paper bags can simply be fastened over individual seed heads for protection from cross-pollination. Since quinoa and lamb's quarters produce many small seed heads up and down their stems, mark the protected seed heads so that you can tell them from unprotected ones at harvest time.
Beets, chard, orach and spinach will not pollinate themselves. These plants need to be caged or bagged in groups so that they can pollinate each other. At least 10 or more plants should be included in each cage or bag for adequate cross-pollination, and to help insure that there are twice as many female as male plants.
Bags or cages need to be windproof to prevent intermingling of the very light pollens. Shake the plants together within their bags or cages regularly, to help the pollen mix move around inside the cage/bag for good pollination.
The Beet Family includes the following species:
Insect-pollinated, biennial broccoli will cross, and must be isolated from, all other members of B. oleracea by one mile for reliable distance isolation (see Cabbage Family). Since broccoli plants are mostly self-infertile, they should be planted in groups of at least 10 or more plants to maintain a decent genetic base and seed viability.
Harvest central heads and some secondary shoots for eating, then leave a healthy side shoot or two on each plant to over-winter and flower for seeds.
Harvest seed pods before the pods split open naturally, but after they have fully matured and dried on the stalks—the seeds will not continue ripening after the plants or stems are cut. Finish drying upside-down in paper bags or hanging in bundles over a tarp. When the plants are completely dry, any seeds that haven't naturally fallen out of their seed pods are easily removed by crumbling the pods.
Broccoli seeds will last for 5 years if properly stored. See also Cabbage Family.
Let broomcorn seeds ripen fully on the plants before harvesting, then place them in paper bags and hang somewhere to finish drying. Broomcorn (a sorghum), can grow to over 12 feet tall and may need support in windy areas. Broomcorn seedhead stems are still used to this day for making... well, brooms.
Broomcorn seeds will last 4 years if stored properly. See also Sorghums.
Insect-pollinated, biennial Brussels sprouts must be kept isolated from all other members of B. oleracea by one mile for reliable distance isolation (see Cabbage Family for the complete list). Brussels sprouts are mostly self-infertile, so seed should be taken from groupingss of at least 10 or more plants. A few sprout heads can be left on each plant to over-winter and flower, so the same plants can produce both sprouts for eating and seeds.
Like other members of the Cabbage Family, seed pods must mature and dry on the plant before harvesting. The pods open readily once they've dried, however, so don't tarry after seed pods are dry.
Seeds of Brussels sprouts will keep for 4 years if properly stored. See also Cabbage Family.
Insect-pollinated, biennial cabbage must be kept isolated from all other members of B. oleracea (see list under Cabbage Family) by one mile. Since cabbages are mostly self-infertile, they should be planted in groups of at least 10 or more plants.
Since you can't have your cabbage seeds and eat 'em, too, you'll have to plant a separate small area with 15 or so cabbages to leave alone to over-winter and produce seed (it's fun to watch the new cabbage shoots burst strangely out from the cabbage heads in the spring). Pick seed pods after they have fully matured and dried on the plants, ideally just after the pods have become brittle and just before they split and spill their seeds.
Cabbage seeds can remain viable for 4 years if properly stored. See also Cabbage Family.
Mostly self-infertile, bee-pollinated members of the Cabbage Family (Brassicaceae) require up to a mile for distance isolation. Members of the same species in the Cabbage Family will cross-pollinate, which presents a problem in species with many members. For instance collards, broccoli, Brussels sprouts, cauliflower, cabbage, kohlrabi and kale (except Siberian kale) are all Brassica oleracea and will cross each other. Brassica rapa includes all the turnips, Chinese mustards and Chinese cabbages. Different species within the Cabbage Family will not cross.
Brassicas are mostly biennial—they grow and mature in the first season, then over-winter before setting seed in spring of their second year. In colder areas where Brassicas don't make it through the winter (they're very hardy), they can be over-wintered in pots in the greenhouse and then transplanted into the garden in early spring to flower and produce seeds.
Since most Brassica seeds remain viable for four or more years, four varieties of a single species can be grown at a time and seed stocks maintained if only one variety is allowed to flower and set seed each year. Alternate-day caging is another option for isolating two or three crossable varieties at a time (the cages must be removed periodically to allow bees to pollinate the flowers... see Alternate-Day Caging).
Brassica seeds will not continue to ripen after harvesting, so allow them to mature and dry completely before removing them from the parent plants—but don't tarry, either. In many Brassicas the seed pods shatter and release their seeds just days after they have matured and dried, especially in hot, dry weather.
The Cabbage Family includes the following species:
Cantaloupes rely on insects for pollination, and will cross other members of C. melo (see a list under Squash Family). Different varieties of C. melo should be separated by ½ mile for safe isolation.
Pick cantaloupes for seed saving when the tendril nearest the melon is completely dried, then store the harvested cantaloupe intact for another 3 weeks before removing and cleaning the seeds. Fermenting the seed/pulp mixture for 3 to 4 days before cleaning can help prevent passing disease and fungus from generation to generation, but is not required. See Cleaning Wet Seeds.
Cantaloupe seeds will keep for up to 5 years if properly stored. See also Squash Family.
Insect-dependent carrots—including wild and cultivated varieties of Queen Anne's Lace—will cross-pollinate and must be separated by ½ mile for safe isolation. In areas where Queen Anne's Lace is a common weed, it will be slightly more difficult to save carrot seeds as caging would exclude the small insects the carrots need for pollination. In this case hand-pollination will be needed... see Carrot Family, below.
Although it is true you can replant carrot tops and get a seed crop from them in the spring with care (they don't root quickly), it takes only a small area to let a few carrots remain for seed every year or two.
Allow carrot seed umbels to ripen and dry on the plant before harvesting and cleaning. After fully drying, the seeds crumble readily from their umbels. Carrot seeds will last 3 years if properly stored. See Carrot Family.
Self-sterile Umbelliferae (also known as the Carrot Family) are dependent on insects' bringing pollen from other plants for fertilization. Umbelliferae require up to 1 to 3 miles for reliable distance isolation. Members of different varieties within the same species will cross, but members of different species will not cross.
Bagging or caging can be used to separate varieties of the same species, in which case hand pollination is necessary. Use a soft-bristle brush to transfer pollen between umbels on different plants during the time the tiny individual flowers are blooming (up to 30 days per umbel).
Alternate-day caging can be used for growing two varieties of the same species without hand pollinating, if you are certain that no crossable wild or domesticated varieties of that species are growing within a mile or so—but whether any of your neighbors are growing different varieties of the same species (e.g., carrots and carrots, dill and dill, etc.) within a mile would be difficult to verify.
The Carrot Family includes the following species:
Insect-pollinated, biennial cauliflower will cross other members of B. oleracea (see list in Cabbage Family) and needs 1 mile for safe distance isolation. Cauliflower plants are mostly self-infertile, and should be planted in groups of 10 or more plants for continuing viability.
Since cauliflower heads don't resprout after harvesting, try one of two ways to get seeds. By cutting carefully, you can leave a branch or two of cauliflower head on the plant to heal and flower in the spring. Probably more reliable would be planting a separate planting just for the seed—these plants would need half or less of the usual amount of room, water and nutrients, as small heads from 10+ plants would still produce plenty of seeds.
Pick seed pods promptly after—not before—they fully mature and dry on the plants. They won't ripen further after the plants are picked.
Cauliflower seeds will last up to 5 years if properly stored. See also Cabbage Family.
Biennial, insect-dependent celery will cross with other celery or celeriac varieties and needs one mile for safe distance isolation. Cut stems high or remove individually from the outside of the plant for eating, then leave a healthy portion of stump in late fall to over-winter and produce seed in the spring. Allow seeds to dry completely on plants before harvesting.
Celery seeds are long lasting and can be kept for 5 or more years when properly stored. See Carrot Family.
Chinese cabbage will cross other members of B. rapa—including Chinese mustard, turnips and broccoli raab—and should be separated from any of these by one mile for reliable distance isolation. Since Chinese cabbages will not self-pollinate, they should be planted in groups of 10 or more plants.
Leave the hearts in 10 - 20 plants in the fall to over-winter and go to seed. Let seeds mature fully and pods dry on the plants before harvesting, as Cabbage family seeds do not mature well off the plant. On the other hand, don't wait too long as the pods shatter and release their seeds readily after drying.
Chinese cabbage seeds will last up to 5 years if properly stored. See also Cabbage Family.
Chinese mustard will cross other members of B. rapa—including Chinese cabbage, turnips and broccoli raab—and should be separated from any of these by one mile for reliable distance isolation. Since Chinese mustards will not self-pollinate, they should be planted in groups of 10 or more plants.
Don't pick seed pods before they have dried naturally on the plants or the seeds will not fully mature. Pick pods as they dry as they will shatter and drop their seeds quickly.
Chinese mustard seeds will last 5 years if properly stored. See also Cabbage Family.
Commonly reproduced by division of bulbs in the garden, insect-pollinated chives also produce viable seeds. Chives cross with other chives (except Garlic chives, which are A. tuberosum); separate varieties by one mile for safe distance isolation.
Let a few clumps of chives flower in the spring and collect the seeds when flower heads are thoroughly dry. The seeds will easily crumble out of the dried flowers.
Short-lived Allium seeds last just one or two years with good germination... they are best replanted annually. See Onions.
Insect-pollinated, biennial collards will cross other members of B. oleracea (see list in Cabbage Family) and needs 1 mile for safe distance isolation. Since collards are mostly self-infertile, they should be planted in groups of 10 or more plants, and some seed collected from each (healthy) plant.
Plants can be eaten from normally—just leave a few leaves in the fall to overwinter and make seeds in the spring. Let the seeds mature fully and pods dry on the plants before harvesting—but don't wait too long or the pods will shatter and you'll lose the seeds.
Collard seeds can last up to 4 years if properly stored. See also Cabbage Family.
Quick-to-bolt cilantro (or coriander) crosses with other cilantro varieties and can be safely isolated with ½ mile of separation between varieties. Allow seeds to dry completely on plants before harvesting.
Cilantro seeds will last for several years when properly stored. See Umbelliferae.
Wind-pollinated corn requires up to a mile for safe isolation in exposed areas. Exact isolation distances will depend on neighboring growers and wind patterns, windbreak protection, etc. (corn pollen is relatively heavy and falls to the ground quickly under quiet conditions).
Instead of distance, "time isolation" can also be used—plant a first, faster-maturing corn crop early enough so that its ears have been pollinated, and their silks dried, before a second, later-maturing crop's tassels have begun to shed pollen (see Time Isolation in Preserving Existing Plant Varieties).
Corn is not self-pollinating—pollen must be carried by the wind from tassels of one plant to silks of another for pollination to occur. Seeds which do not get pollinated will not form kernels. For this reason it is important for good pollination to plant corn in blocks instead of in a single long row.
Allow corn ears to mature and dry on the stalks, but harvest as soon as the ears are dry to keep them from getting rained on or the kernels may rot or sprout. Watch also for ants attacking kernels. Let corn kernels continue to dry thoroughly on the cobs (with husks shucked) in a protected spot. After the kernels are thoroughly dry, rub them off the ears with your hands.
Be sure to harvest seeds from at least 100 plants to keep your seed population strong from year to year (see How To Avoid Inbreeding Depression in Corn, below).
Sweet corn seeds remain viable for up to 3 years when properly stored; starchier dent, popcorn and flint corns can remain viable for 5 or more years.
A prime consideration when growing corn for seed is the size of the 'parent' planting. Corn represents an extreme example of the necessity for growing a large enough number of plants to avoid 'inbreeding depression'. Inbreeding depression—weakening of a population by too narrow a genetic base—is a direct result of collecting seed from too few parents.
Once a batch of seed is produced from too few parents, the genetic base of that group of seeds is permanently narrowed unless new genetic material can be introduced. Thus, an inbred seed batch's genetic base can be broadened by mixing the batch with a healthy batch of the same variety grown by a different grower.
Inbreeding is better avoided than 'fixed', however. Grow at least 200 corn plants to avoid inbreeding depression. Remember to collect some seeds from each plant, and make sure that at least 200 plants are included in the planting, with at least 100 allowed to produce seed. If too-few plants survive to produce a healthy seed batch, mix the batch with more seeds from another batch before replanting.
Insect-pollinated cotton plants need at least 800 feet for reliable distance isolation. Alternate-day caging is practical, since the plants are not overly large. In most urban locations it is unlikely that neighbors will be growing cotton, but precautions should be taken if you are growing a rare or difficult-to-replace variety.
Allow cotton seed pods ('bolls') to pop open completely, exposing the cotton fibers within, before harvesting the seeds. The small bean-sized seeds are found within the cotton and are fairly difficult to remove in any quantity—it's easy to see how important the cotton gin is to the cotton industry after you've cleaned a few cotton seed heads!
Cowpeas are self-pollinated, and different varieties of cowpea do not commonly cross-pollinate each other.
Allow pods to dry on the plants before harvesting, and don't allow the dried pods to get rained on. Try to avoid using seed pods for seed saving after they have been thoroughly wetted as the seed may be compromised (or even sprout in the pods!).
Cowpea seeds, properly dried and stored, will keep for 3 or more years. See also Bean Family.
Cucumber varieties will cross each other (except Armenian cucumbers, which are actually C. melo) and should be isolated by ½ mile for reliable distance isolation between varieties.
Cucumbers should be left on the vine to ripen to well past the eating stage before being harvested for seed, and then aged another 20 days in the cuke before the seeds are removed and cleaned.
Cucumber seeds are long lasting and may remain viable for as long as 10 years under good conditions. See Squash Family.
Dill is insect pollinated and different varieties may cross unless separated by one mile. Harvest individual heads as they dry on the plants, since they ripen over a period of time.
Dill seeds remain viable for 3 or more years if properly stored. Also see Carrot Family.
Self-pollinating Eggplants can be safely isolated by 50 feet of separation.
Eggplants should be left on the plants until well past the eating stage before harvesting for seed. The eggplants will have gone past their normal, ripe color and become translucent and dry (usually a dull, unattractive whitish, yellowish, or brownish color).
It's a good idea to keep eggplants off the ground during ripening, since they may begin to rot when they rest on the ground. Clean seeds according to the wet-cleaning process outlined in Cleaning Wet Seeds.
Long-lasting eggplant seeds will remain viable for 5 or more years if properly stored.
Fava beans are self-pollinated, and different varieties do not commonly cross-pollinate each other. They can be crossed by insects, however, and should be caged or isolated by 100 feet if purity is important.
Wait for pods to fully dry on the plants before harvesting. Quickly harvest and dry any pods that get wetted by rain, and discard any seeds that have gotten soaked.
Fava seeds, properly dried and stored, will keep for 3 or more years. See also Bean Family.
Fennel will cross with other Fennel varieties and should be separated by ½ mile for safe distance isolation. Allow umbels to dry completely on plants before harvesting seeds.
Properly stored, fennel seeds will keep for 3 or more years. See also Carrot Family.
Garlic is not commonly reproduced from seed; save healthy bulbs and replant individual cloves separately. If you want to save and replant seeds from garlic for breeding purposes, just harvest the seed after the flower heads have dried on the plants. See also Onions.
Garlic Chives can be reproduced by division of clumps or by saving seeds. Allow seeds to dry thoroughly on plants before collecting. Seeds are short-lived and should be planted within 1 or 2 seasons. See also Onions.
Gourds can cross other hard-shelled gourds (except ornamental colored striped or warty 'gourds', which are Cucurbita pepo) and should be separated by ½ mile for reliable distance isolation. Allow gourds to thoroughly dry on the vines before harvesting for seeds.
Properly dried and stored, gourd seeds will last for several years. See Squash Family.
Most kales are Brassica oleracea, and will cross with other members of this species such as cabbage, collards, broccoli and cauliflower. Siberian Kale, however, is Brassica napus and will cross with rutabagas and rape, but will not cross with the members of B. oleracea. See also Cabbage Family.
Let seed pods mature and dry on the plants before harvesting, or the seeds will not be fully mature. Harvest quickly after drying, though, as the pods often shatter and drop their seeds soon after they dry.
Kale seeds can last up to 4 years if properly stored.
There are two species of lamb's quarters, the green (C. alba) and the magenta-centered (C. giganteum). Varieties in the same species will cross, but green and magenta lamb's quarters will not cross each other.
Allow seed heads to dry on the plants, and then hang upside-down in paper bags to finish drying. Many of the tiny seeds will fall out naturally, and the remainder can be crumbled from the heads and winnowed.
Lamb's Quarter seeds are very long-lived. See also Beet Family.
Lettuce is self-pollinating, but plants can cross under some circumstances. 25 feet of separation is generally sufficient to prevent crossing, however.
While each flower opens only during the morning of one day, the flowering period is long and there are almost always flowers blooming on the plants. This means that a flowering plant will have flowers and seeds in all stages of maturity.
Gather dried seed heads (they are easy to recognize) every couple or three days as they ripen and dry, or wait until most seed heads have dried and hang the plant upside down over a tarp or in a paper bag (harvest dry seeds if rains threaten).
Lettuce seeds can remain viable for 3 years if properly stored.
Melons will cross other members of C. melo and should be separated by ½ mile for reliable distance isolation. Melons produce wet seeds. Allow melons to ripen on vines until skins are hard, then store for an additional 3 weeks before removing and cleaning their seeds. See Cleaning Wet Seeds.
Melon seeds can be kept for up to 5 years if properly stored. See also Squash Family.
Varieties of mustard within the same species will cross each other, but there is no crossing between varieties of different species. This means you can safely grow one variety of mustard greens (B. juncea), one Black mustard (B. nigra) and one Chinese mustard (B. rapa) without danger of crossing—if your neighbors aren't growing them.
Separate varieties from the same species by ½ mile for reliable distance isolation—this includes wild members of the species, however. Since mustards have escaped cultivation and become rampant in most parts of the world, caging would in many (if not most) cases be needed to ensure absolute purity for important varieties.
Let seed pods dry fully on the plants before you pick them, but watch closely as the pods may shatter quickly.
Mustard seeds will last for 4 or more years if properly stored. See Cabbage Family.
Insect-pollinated okra needs at least ¼ to 1 mile for safe distance isolation. Time isolation is practical for growing two varieties in one season, since okra is a long-season plant (it may be commonly grown in your area, however, so don't forget the neighbors). Save seed from the early planting before the late one starts to flower... to safely save seed from the later planting, you might at some point have to pull the early planting, or prevent their flowers from opening and crossing the later planting.
Caging can also be used, but large cages would be needed as plants can be fairly tall (plants planted later in the season would flower before getting as tall as earlier-planted ones).
Allow pods to dry on the plants until they begin cracking, then split open to remove seeds and finish drying. Okra produces a high percentage of 'hard seed' (seeds with seed coats which are not readily permeable to water) and can be slow to germinate after thorough drying or long storage. For best germination, soak okra seeds overnight before planting to give hard seeds time to imbibe water.
Okra seeds can be stored for up to 4 years.
Insect-pollinated Onion Family plants need up to 1 to 3 miles for safe isolation. Closely planted groups of plants can be caged or bagged and then hand-pollinated.
To hand-pollinate, remove covers and use a fine, light paintbrush to mimic the action of visiting insects, thoroughly mixing pollen between several flowers. Make sure to hand-pollinate the flowers during a time (such as early morning or late evening) when insects are not present, and replace covers quickly and securely.
Allow seeds to ripen and dry on the plants, then harvest quickly to avoid losing seeds. Onion seeds are short-lived and should only be stored for one or two years before planting.
Insect-dependent and biennial, parsley can cross other parsley varieties and should be separated by 1 mile for reliable distance isolation. Allow seeds to mature and dry on the plants before harvesting.
Parsley seeds can be kept for 2 or 3 years if properly stored. See Carrot Family.
Self-pollinating peas do not readily cross—varieties separated by 50 feet are reasonably safe from crossing. For even greater certainty for preservation purposes, they can be bagged or caged.
Allow pods to reach full size before harvesting the seeds—ideally, pick pods after they have dried on the vines. Peas are susceptible to mold if wetted after drying, however. If peas have reached full size, they can be harvested before they are dry if rains threaten. After the pods are completely dry, they crumble easily to release the seeds.
Pea seeds remain viable for 2 years if stored properly. See also Bean Family.
Self- or insect-pollinated, pepper varieties of the same species will cross-pollinate. There is no crossing between varieties of different species, however. You can safely grow one hot or sweet pepper (C. annuum) and one Tabasco pepper (C. frutescens) without danger of their crossing.
Peppers within the same species can be safely isolated by 500 feet of separation, or they can be caged since the plants are not overly large. Allow peppers to ripen and dry fully on the plants before harvesting the pods. Wash your hands thoroughly with soapy water after harvesting hot pepper seeds, since the residues will burn eyes and lips for some time after contact!
Pepper seeds will keep for 2 or 3 years if properly stored.
Pumpkins can belong to either C. maxima or C. pepo. Varieties within these species will cross each other, but C. maxima will not cross C. pepo. Find your pumpkins' species from the seed company where you purchase them, or look them up in Suzanne Ashworth's excellent seed saving resource, Seed to Seed.
Pumpkins produce wet seeds (see Cleaning Wet Seeds). Store fully-ripe pumpkins for 3 weeks after harvesting before removing and cleaning the seeds.
Pumpkin seeds, like those of other members of the Squash Family, benefit from fermenting after being removed from the fruit—see Why Ferment Some Seeds?.
Pumpkin seeds will keep for 5 or more years if properly stored. See also Squash Family.
Radishes will cross other radishes including daikon, but not turnips (Brassica rapa) or other members of the Cabbage Family. Separate radish and daikon varieties from each other by ½ mile for safe distance isolation.
Pick pods after they dry completely on the plant. Pick every day or two, as the pods will break open naturally to release their seeds soon after drying.
Radish seeds can last 4 or 5 years if properly stored. See also Cabbage Family.
Self-pollinated broomcorns, grain sorghums and cane sorghums are all in the same species (Sorghum bicolor), but they do not cross readily with each other. For certainty with rare varieties, though, they can be bagged (individual flower heads), caged (shorter types) or separated by 600 feet.
Allow the seeds to dry on the plants before harvesting and winnowing. Use of diatomaceous earth in stored seeds is advisable since sorghum seeds are attractive to pests.
Sorghum seeds will last 4 years if stored properly.
Bee-pollinated members of the Squash family (Cucurbitaceae), require up to a mile for distance isolation. Different species of Cucurbitaceae do not cross-pollinate, so one variety from each species can be grown together without danger of crossing. For instance, one variety of crookneck or zucchini (Cucurbita pepo), one butternut or acorn squash (Cucurbita moschata), one watermelon (Citrullus vulgaris), one cantaloupe or muskmelon (Cucumis melo), one luffa (Luffa aegyptiaca), a hard gourd (Lagenaria siceraria) and a cucumber (Cucumis sativus) could all be grown together without crossing each other.
Find out from your seed company which species your varieties belong to, or consult Suzanne Ashworth's Seed to Seed for a comprehensive listing of Cucurbitaceae varieties and the species to which each belongs (there are no reliable, general rules for non-botanists to determine species).
Insect-pollinated and are self-infertile, if Cucurbits are isolated by caging, bees must be allowed to reach and pollinate the different varieties on alternating days (see Caging).
Cucurbits can also easily be pollinated by hand (use pollen taken from the same variety). After hand-pollinating the flowers, replace the cages, or bag or tape individual flowers shut to prevent further pollination. For more detail, see Seed to Seed.
Squashes should be fully mature before harvesting—for summer and other soft squashes, this is well past the eating stage. Harvest when skins are hard and leathery. Melons should be fully ripe before they are picked, as some will not complete ripening of their seeds if they are picked too soon. Harvest melons only after the vine tendril nearest the individual melon in question has dried and withered, and wait another 3 weeks before opening the melon to harvest the seeds. Clean the seeds according to directions in Cleaning Wet Seeds.
Allow dry-seeded members of the Cucurbit family (i.e., gourds, luffa) to dry on the vines until the shells are dried and the seeds inside rattle if shaken. Open the gourd and clean the seeds by winnowing.
After harvesting wet-seeded Squash family fruits, store the unopened fruits for another 20 days before removing the seeds. This is because some squash family seeds gain in size and viability for 20 days after harvesting. After the 20 day waiting period has passed, cut the fruits open and remove the seeds to prepare them for storage.
Squash seeds can be fermented for higher germination and better disease-resistance (see Why Ferment Some Seeds?—don't ferment seeds if they appear to have already naturally fermented while waiting in the wet fruit, as evidenced by the smell and appearance of the seeds and pulp).
After fermentation, clean the seeds by pouring off pulp and dead seeds (seeds which will float are dead and should be discarded). Use the same cleaning directions as for tomato seeds (see Cleaning Wet Seeds). Whether you've fermented the seeds or not, rub them underwater between your fingers gently but thoroughly while cleaning them, to remove the naturally occurring gel from their coats. Dry the cleaned seeds on a shiny surface (they will stick to paper) until they are brittle, but—as always!—do not use heat.
The Squash Family includes the following species:
Insect-pollinated sunflowers need from ½ to 3 miles for isolation. Wild sunflowers—which will cross most cultivated varieties—are very common, making reliable distance isolation difficult at best. Uncommon species (such as Silver-Leaf Sunflower, H. argyophyllus) can probably be grown without danger of crossing, but most varieties will require bagging or caging for certain isolation. Caging is not practical for most sunflowers because of their size.
Since some varieties are self-infertile and have to be pollinated by pollen from other plants, caged or bagged sunflowers should be hand pollinated. Once a day while florets are blooming (one to two weeks per head), unbag two heads at a time and gently rub them together or use a soft-bristle paint brush to transfer pollen from one head to another. Hand pollinate a different pair of heads each time if possible. Rebag seed heads promptly after pollinating to keep insects from interfering.
Allow sunflower heads to dry on the plants before harvesting whole heads and hanging them upside-down in a protected spot to complete drying. The seeds can then be removed from the heads by vigorous rubbing. Store and plant the seeds in their kernels for protection.
Sunflower seeds can be kept for 5 or more years if properly stored.
Swiss chard and beets are wind-pollinated and in the same species. All varieties of beets and Swiss chard will cross each other. Different varieties must be caged, bagged or separated by up to 5 miles for safe distance isolation.
Let seeds mature and dry on the stalk before harvesting, the complete drying before gently rubbing the seeds off their stalks. Each 'seed' is botanically a berry, and contains several actual seeds (breaking them apart would damage many of the seeds). This is why chard and beets often come up several plants to a spot despite the most carefully-frugal sowing efforts.
Chard seeds will last for up to 5 years if properly stored. See also Beet Family.
Tomatillos are self-pollinating and do not commonly cross, but can either be caged or separated by 500 feet for certainty with purity.
Allow the fruits to ripen thoroughly on the vines, then harvest the fruits to remove and clean the seeds as described in Cleaning Wet Seeds.
Tomatillo seeds can be kept for up to 3 years if properly stored. See also Tomatoes.
Almost all modern tomatoes can be safely grown without isolation and will not cross—'currant' tomatoes (such as Cherry Tomatoes), and 'potato-leafed' tomatoes (such as Brandywine) are possible exceptions and may cross other currant or potato-leaf varieties. Grow as many standard tomatoes as desired, but grow only one currant tomato or one potato-leaf tomato at a time to ensure purity (or cage them, or separate varieties by 500 feet). Currant and potato-leaf tomatoes will not usually cross with common tomato varieties.
It's best to not plant all a valuable variety's seeds in one season until you are sure it doesn't cross with any other varieties you grow.
Allow tomatoes to ripen thoroughly on their vines to at least the eating stage before harvesting them to collect their seeds. Upon harvesting, tomato seeds are best fermented in order to remove a germination-inhibiting gel which covers the seeds, and to kill diseases. In nature, fermentation of fallen ripe fruits removes this gel, and this process is imitated when preparing tomato seeds. See Fermenting Seeds and follow the directions.
If fermenting tomato seeds seems too much trouble, they will still germinate if the slippery gel surrounding the seeds is carefully rubbed off while you're cleaning them. Seeds treated this way will germinate, but they will not have had the protection of the fermentation process killing disease organisms. If you noticed any problems with your plants (leaves spotting or dying, inexplicable wilting, etc.), the extra trouble of fermentation will be well worth the effort.
Dry your tomato seeds on a piece of glass or a shiny plate—the wet seeds will stick to paper and be difficult to remove without damaging them.
Tomato seeds will store safely for 4 or more years after being properly dried and stored.
Turnips are in the same species and will cross with—and must be isolated from—Chinese Mustards and Chinese Cabbages by 1 mile of separation or by alternate-day caging. Turnips are mainly self-sterile, so grow at least 10 plants for adequate pollination and seed production.
As with other Brassicaceae, allow seeds to ripen thoroughly on the plants before harvesting.
Turnip seeds can last 4 or 5 years if properly stored. See also Cabbage Family.
Watermelons will cross other watermelons and varieties should be separated by ½ mile. Watermelons produce wet seeds and should be allowed to ripen to past the eating stage before harvesting, since seeds do not continue ripening significantly after melons are harvested. Pick after the tendril nearest the melon has completely withered and dried, then store an additional 3 weeks before removing and cleaning the seeds according to directions in Cleaning Wet Seeds.
Watermelon seeds will remain viable for 5 or more years if properly stored. See also Squash Family.
Reprinted from Vegetable Seed Savers Handbook, Jack Rowe 1998, howtosaveseeds.com