www.savingourseeds.org offers a series of manuals on seed saving in the Mid-Atlantic and Southeast, which we highly recommend. The manual on isolation distance has been especially useful. Seed to Seed by Susan Ashworth; The Organic Seed Grower by John Navazio; and The Seed Garden by Micaela Colley and Jared Zystro are excellent, in-depth books about seed growing, saving and production. We often use them for reference about particular crops.
When saving seeds it is good to be aware of potential seed-borne disease issues. http://vegetablemdonline.ppath.cornell.edu/cropindex.htm is a good resource for identifying diseases in vegetable crops. Organic Seed Alliance has seed production guides for many crops that include information about seed-borne disease and how to manage it. See https://seedalliance.org/all-publications/ and search for “disease.”
Hand pollination is another useful tool for seed saving – you can ensure that your seed is pure if you are uncertain that you can maintain proper isolation distances. Seed Savers Exchange has many useful video tutorials, including how to hand pollinate squash and how to hand pollinate corn, regarding various seed saving techniques.
Collards
Planting: Direct sow or transplant in the late summer, or in the spring. Row spacing: 24-36 inches. Plant spacing: 8-12 inches.
Seed Saving: Plant in late summer or early fall. Isolate from other Brassica oleracea seed crops by ½ mile. Save seed from at least 60 plants to prevent inbreeding depression. Clip branches with seed pods when they turn brown. Clip the whole plant when it is mostly brown. Don’t wait too long because rain causes mold that often damages the seeds. Dry on a tarp (don’t stack much more than one layer deep and consider using a fan) before foot threshing and winnowing.
Corn
Planting: Direct seed when the soil has warmed to at least 60 degrees. Row Spacing: 30-40 inches. Plant spacing: 8-12 inches. Plant at least four rows (they can be short rows) for adequate pollination.
Seed Saving: Save seed from at least 100 plants (ideally 200) to prevent inbreeding depression. GMO contamination of corn is a big issue. If there is any GMO corn being grown within a few miles you may need to hand pollinate. Time isolation, or planning your crop so that it is tasseling at a different time from other corn, is another option. Leave ears on stalks till they are mostly dried out, but they can be picked earlier – as soon as kernels feel hard. Sweet corn seed should be harvested on the early side as it is more susceptible to mold damage associated with rain. Spread out and continue drying after harvest.
Cucumber
Planting: Direct seed or transplant after danger of frost has passed, or at least 75 days before first frost (100 days for a seed crop). If transplanting, take care not to disturb the root ball. Row Spacing: 5-6 feet. Plant spacing: 10-15 inches. You may want to use row cover to protect small plants from cucumber beetles. Remove cover at or before flowering. Harvest every 2-3 days.
Seed Saving: Cucumbers must be isolated from other plantings by at least a quarter mile, or else hand pollinated. Leave fruits on the vine until they turn yellow, and as long as possible before they start to rot. Fruits can be further ripened off the vine if necessary. Scoop out seeds and ferment for 2-3 days before processing with water; dry on a screen.
Note: cucurbit viruses, such as Cucumber Mosaic and Squash Mosaic, can be seedborne. Do not save seeds from infected (stunted and deformed) plants or fruits.
Eggplant
Planting: start indoors in April and transplant after danger of frost has passed. Consider using row cover to control flea beetle damage to young plants. Row Spacing: 3 feet. Plant Spacing: 18-24 inches. Harvest with clippers.
Seed Saving: Eggplant should be isolated from other varieties by at least 200 feet. Leave fruits on the vine until they turn yellow, but harvest before they start to rot. Let fruits cure off the plants for up to two weeks. Cut each fruit into a few pieces and place in a bucket to mash with a 2×4. Add water and ferment for 1-2 days. Process with water and dry on a screen.
Gourds
Planting: Direct seed or transplant as soon as possible after danger of frost has passed. Row Spacing: 12-15 feet. Plant Spacing: 3-4 feet. In a garden setting, consider only turning and fertilizing a 2-3 foot circle, planting several seeds and letting the vines roam the rest of the yard. Vines can grow up to 50 feet long, so give them adequate space away from other crops, or plan to train them. Using an arbor or a strong trellis will yield straight necks and fruits that aren’t blemished where they contact the ground.
Seed Saving and Processing: Gourds should be isolated from other varieties by ¼- ½ mile, or hand pollinated. Harvest at frost (some frost is ok for fruits) and cure for 1-3 months. It generally works to cure gourds outside, but goes faster in a somewhat heated space like a basement. Place them in a single layer, possibly using a fan to prevent excessive mold. They are ready when they have mostly lost their green coloring, or when the seeds and pulp slosh or rattle when shaken vigorously (doesn’t work for all varieties). Some mold is okay. If you plan to save the seeds, do not wait until the inside is completely dried out. Use a hole saw to drill holes for birdhouses. Or use a hand saw to cut off tops or to cut in half etc. With patience and innovative use of kitchen utensils seeds and pulp can be removed through small openings. Putting water in the gourd and shaking can help. Fermentation is not necessary but can help in separating seeds and pulp. Dry seeds on a screen.
Melon
Planting: Direct seed or transplant after danger of frost has passed, or at least 105 days before first frost. If transplanting, take care not to disturb the root ball. Row Spacing: 6 feet. Plant Spacing: 18-30 inches. You may want to use row cover to protect small plants from cucumber beetles. Remove cover at or before flowering. Harvest: You can tell when a melon patch is starting to ripen by smell. They also change color and slip easily off the vine when ripe. Different melon varieties require slightly different harvest criteria. Harvest every 2-3 days.
Seed Saving: Melons need at least ¼ mile isolation from other varieties to prevent crossing. When melons are ripe, cut open and scoop out seeds and pulp into a container. Ferment for 2-3 days before cleaning with water; dry on a screen.
Note: cucurbit viruses, such as Cucumber Mosaic and Squash Mosaic, can be seedborne. Do not save seeds from infected (stunted and deformed) plants or fruits.
Okra
Planting: Direct seed after danger of frost has passed. Row spacing: 3-6 feet. Plant spacing: 18-24 inches. Harvest: Clip young pods every couple days before they get too big and become tough (unless saving seed). Wear gloves and long sleeves to prevent skin irritation.
Seed Saving: Okra needs at least ¼ mile isolation from other varieties. Leave pods on plants until they develop lengthwise scoring, and the seeds turn dark green or grey. Clip and spread out in a dry place until fully dry. Rain can cause mold and damage seed, so don’t wait too long to harvest. We usually open pods by hand.
Peppers
Planting: Plant indoors in March or April and transplant after danger of frost has passed. Row spacing: 3 feet. Plant spacing: 18-30 inches.
Seed saving: Sweet peppers need 150-200 feet isolation from other varieties, but should be at least 300 feet from any hot peppers. Pick peppers when fully ripe, and ideally let cure further for 2-3 days. Cut open and remove the core. Discard any moldy or discolored seeds. Fermentation (1-2 days) is not necessary but can make it easier to get seeds off cores and provides separation of underdeveloped seed (they float). Small peppers can be mashed whole and fermented for 1-2 days. Process with water and dry on a screen.
Note: Bacterial speck and bacterial spot are seed-borne nightshade diseases that can be controlled by hot water treatment. We have never seen these diseases on our crops but use hot water treatment before planting as a precaution. See http://vegetablemdonline.ppath.cornell.edu/NewsArticles/HotWaterSeedTreatment.html
Rutabaga
Planting: Direct seed in mid or late summer (till September 1st in Central Virginia). Row spacing: 18-24 inches. Plant spacing: Thin to 6 inches.
Seed saving: Rutabaga needs half a mile isolation from other varieties to prevent crossing. Plant in late summer. Dig up mature roots in late winter or early spring, replanting the good-shaped ones for seed. At least 60 plants are needed to prevent inbreeding depression. Use 3 by 2 foot spacing for seed production. Clip branches as soon as they turn from green to tan, and let dry further on a tarp before foot threshing and winnowing. Rain can cause mold that damages the seeds, so don’t delay the harvest.
Squash
Planting: Direct seed or transplant after danger of frost has passed. Take care not to disturb the root ball if transplanting. Row spacing: 5-6 feet for summer squash; 9-15 feet for winter squash and tropical pumpkins. Plant spacing: 1-2 feet for summer squash; 2-4 feet for winter squash. You may want to use row cover to protect small plants from cucumber beetles. Remove cover at or before flowering.
Seed Saving: There are several species of squash (moschata, pepo, maxima and argyrosperma), and you need to know what species you are working with. Different varieties of the same species need at least ¼ mile isolation for seed saving, or else plan to hand pollinate. One variety of each species may be grown in the same garden. Leave summer squash fruits on plants to ripen as if they were winter squash. After harvest, let squash cure for a few more weeks for full seed development. Cut open and scoop out seeds. Ferment with water for 2-3 days (more when its cold out) before processing with water. We often rub the seeds over quarter-inch hardware cloth to remove much of the pulp. Some squash varieties have seeds that largely don’t sink.
Note: cucurbit viruses, such as Cucumber Mosaic and Squash Mosaic, can be seedborne. Do not save seeds from infected (stunted and deformed) plants or fruits.
Tomatoes
Planting: Start indoors in April and transplant after danger of frost has passed. Can also be direct seeded after last frost. Row spacing: 5-6 feet for most varieties. Plant spacing: 2.5-4 feet. We use cages made out of concrete reinforcing mesh. A roll of remesh makes about 30 cages. For some plantings we use string weaving.
Seed saving: Isolate from other varieties by 25-50 feet, and 150 feet from cherry tomatoes. Pick ripe tomatoes and let cure till very ripe. Cut out any mold or rot that has developed before placing tomatoes in a bucket to mash. Ferment 2-3 days and then process with water. Dry on a screen.
Note: Bacterial speck and bacterial spot are seed-borne nightshade diseases that can be controlled by hot water treatment. We have never seen these diseases on our crops but use hot water treatment before planting as a precaution. See http://vegetablemdonline.ppath.cornell.edu/NewsArticles/HotWaterSeedTreatment.html
Watermelon
Planting: Direct seed or transplant when danger of frost has passed. Row spacing: 6 feet. Plant spacing: 2 feet. You may want to use row cover to protect small plants from cucumber beetles. Remove cover at or before flowering.
Seed Saving: Isolate by at least ¼ mile from other watermelon varieties, or else hand pollinate. Scoop insides out of ripe melons. Press with a large strainer if you want to save juice. Let seeds and pulp ferment for 2 days before processing with water. We often rub the seeds over quarter-inch hardware cloth to remove much of the pulp. Some watermelon varieties have seeds that largely don’t sink.
Note: cucurbit viruses, such as Cucumber Mosaic and Squash Mosaic, can be seedborne. Do not save seeds from infected (stunted and deformed) plants or fruits.