As fall approaches, enthusiastic gardeners want to store seed for next year's production. Before you decide to save seed from your plants, it's important to consider whether saving seed will get you the type of plants you want.
It makes a difference whether your plants are...
open-pollinated, which means that they produce seed that will yield plants similar to the parent
cross-pollinated, which means that they could pick up characteristics from nearby plants
hybrid cultivars, which means that they have special characteristics unlikely to carry into a subsequent year.
Many modern cultivars are hybrids, designated as "F1" on the label. These have been specially bred for vigor, pest resistance, high-yield and other characteristics. Seeds saved from these plants will generally produce inferior plants the following season. For example, if you save seeds from 'Sweet Burpless Hybrid' cucumber and plant them next year, they will produce cucumber plants whose growth and fruiting will be inferior to the parent.
Most older cultivars of vegetables, including heirloom varieties, are open-pollinated. These will reproduce reasonably true to type if planted in isolation. If you plant 'Straight 8' cucumber away from other cucumbers and save the seeds, next year's plants will be pretty much like 'Straight 8.'
All things considered, you will do best to save seeds of open-pollinated cultivars and self-pollinated peas, beans, lettuce and tomatoes. You can be pretty sure of getting true to type seeds without isolating these crops, so long as you do not start with hybrid parents.
Cross-pollinated vegetables are pollinated by other cultivars of the same kind of plant. For example, 'Long Standing Bloomsdale' spinach will cross-pollinate with 'Melody' and other spinach cultivars. If you plant both near each other and save their seeds, next year's generation will have traits of both parents.
In addition to spinach, beets, broccoli, cabbage, radish and several other vegetables cross-pollinate. You can be sure of getting seeds of plants that will be fairly true to type only if you isolate your insect pollinated crops by 200 yards and your wind-pollinated crops by a mile.
The vine crops, eggplant, peppers and celery are partially cross-pollinated, depending upon the environment. Isolate them from others of their kind, just to be sure.
Annuals
Saving seeds from annuals is easy, but the seeds of biennials are produced in the second season, following a cold period. Let your plants overwinter and collect seeds the following year.
Root Crops
Root crops, like carrots and beets, are tricky, since the roots must be harvested to judge their quality, prior to selecting for seed-saving. Carefully dig the plants in the fall, select those with the best characteristics and replant them right away after removing their tops. Snow cover will naturally protect them over winter. If you live where snow cover is light or unpredictable, mulch the plants with a few inches of straw after the ground has frozen. Winter mulch protects roots, the the roots will produce new tops and a flower next spring. In the second year, the root will be inedible. Let the seeds ripen and you're in business, two years after the first crop.
Curcurbits
In American gardens, we plant seven species of "cucurbits" divided among three genera, which, in general, will not cross pollinate. Watermelon will not cross with cucumber, and neither will cross with zucchini. There are four species within the genus Cucurbita, some of which cross within the same species and others with other species. It can be confusing. To detail just a few: Jack O Lantern pumpkin and zucchini will cross. Butternut squash and Kentucky field pumpkin will cross. Buttercup squash, hubbard squash, and Big Max pumpkin cross. Cushaw pumpkins cross with some gourds. All of this only matters if you plan to save the seed. The fruit of this year's crop will be unaffected by the cross.
Beans, peas, and crucifers bear seeds in pods, which need to turn brown before you harvest them. Then dry them for another week or two in a warm place, shell them, and store the seeds in a paper bag in a dry room below 50 degrees Fahrenheit.
Some seeds need to be soaked in 122 degrees F water to protect them from seed-borne diseases. Soak cabbage seeds for 25 minutes, and soak seeds of broccoli, cauliflower and Brussels sprouts for 18 minutes. Then dry in a warm place. Again, store dried seeds in a paper bag or paper envelope.
Pepper, melon, pumpkin and squash seeds should be scraped onto a paper towel to dry, then stored in a paper envelope or bag, as you would other seeds.
Pick ripe tomatoes and cucumbers and squeeze the pulp, including the seeds, into a glass or plastic container. Add a little water and let the goo ferment for several days at room temperature, stirring occasionally. Viable seeds will settle, while dead seeds will float. Pour off the pulp, water and floaters and spread the viable seeds in a single layer on a paper towel to dry. Store all seeds in an envelope or paper bag in a cool, dry place.
No matter what kind of seeds you are saving, mark the envelope or paper bag with the cultivar, kind of plant, and date of harvest with permanent marker or pencil.
Seeds are living, and holding them in a paper bag or envelope in a cool (about 50 degrees F), dry place will slow their physiological processes, allowing for maximum storage life. When properly stored, seeds remain usually viable from one to five years.
