March 6, 2023 at 9:55 a.m.
Seed saving makes for sustainable gardening
Seed saving makes for sustainable gardening
Pollination can occur in a variety of ways. Plants can be pollinated by wind, insects, or both. Pollination can also occur in a close flower without any other intervention, she said. Pollination can happen not only in one flower itself, but also in flowers on the same plant, or on flowers of the same species on another plant. Some plants have separate male and female flowers, she said, which could be on the same plant or on different plants.
Self-pollination happens in the same flower, she said. Some vegetables are good examples of plants that pollinate themselves without help from insects, for instance. The genetics of these plants are homogenous, Johnson said, meaning their seeds will produce plants with the same characteristics of the parent plant. This is often most desirable for gardeners looking to save seeds for use in future gardens.
"Over time when you have self pollination going on, or controlled crosses, you can virtually eliminate genetic variation," Johnson said. "Then you have what we call 'pure seed lines' that are established."
With cross-pollination, however, pollination happens between flowers on different plants. This means there can be a great deal of genetic variation in the plants coming from those seeds. This type of pollination can occur between plants or between different flowers on the same plant. Of course, this can make a plant more resilient to certain diseases or pests and can provide value for the gardener as well as the plant. However, for seed saving purposes, this genetic variation may result in some unfavorable qualities of the plants that grow from those seeds. With plants that cross pollinate, their own pollen is usually not compatible with itself, so it will need pollen from another plant.
Pure lines, Johnson said, come from heirlooms and open pollinated crops. Self-pollinated crops also fall into this category. Open pollinated crops have stable genetics and little variability. They usually grow in fields where they self-pollinate and cross-pollinate. The plants are all fairly similar but some genetic "drift" can occur, so Johnson recommended gardeners remove any non-uniform plants from the field.
An heirloom, she said is an open pollinated crop as well. These varieties become heirloom when they are over 50 years old.
Johnson also spoke about hybrid seeds. Hybrids are produced by taking the stable generation plants and crossing them with each other to produce a hybrid that has various preferred characteristics. F1 hybrids are the first generation seeds produced by this type of cross-pollinating. Johnson said it takes quite some time to create a genetically stable F1 hybrid. However, once that is achieved, plants may be more vigorous, more productive or disease resistant. It can take 7-8 year to produce pure lines.
The main disadvantage, for seed savers, with hybrids is that they do not breed true and seeds may even be sterile. Hybrid seeds, she said, are not useful for saving. Many popular varieties such as Burpee Big Boy and Early Girl tomatoes as well as Sweet Success cucumbers are F1 hybrids.
For those new to seed saving, Johnson recommended self-pollinated crops such as lettuce, beans, peas and heirloom tomatoes. Gardeners and seed savers can also control pollination of seeds so the next generation of plants and fruits or vegetables will resemble the parent plant. She also said that seeds from hybrids should not be saved. They are unlikely to resemble the parent plant.
Johnson also spoke about controlling pollination of cross pollinated crops. They are much more difficult, however, making them not good candidates for new seed savers. These are crops such as onions, cucumbers, corn, pumpkins, squash, broccoli, beets, carrots, cabbage, cauliflower, eggplant, melons, radishes, spinach, Swiss chard and turnips. If pollination in these plants is not controlled, it is likely the plants produced will not resemble the parent plants.
Johnson spoke next about how to control pollination. The idea, she said is to prevent insects or wind from pollinating plants when the gardener does not want them to. Plants can be pollinated by people. Hand-pollinating can be done with a paintbrush or some similar object. Plants that can be pollinated by flowers from the same plant can be bagged to keep unwanted pollen out of the plant. Also, she said, only growing one type of a vegetable, for instance, can also help control pollination. In larger settings, large distances between varieties can help ensure plants only pollinate others like themselves.
Johnson also went into some specific crops. Beans, for instance, are self-pollinating. The seeds should be allowed to mature on the vine. This is later than a person would normally harvest the beans to eat. Then the gardener can pull the plant up or harvest the pods as they dry. They should then be dried in a cool area for one to two weeks. After that time they can be shelled and stores in a cool, dry area in a paper bag. Beans and cowpea seeds, she said, can be kept for three or more years.
Pea varieties, she said, should ideally be separated by 50 feet or more, but cross-pollination is rare between varieties. Pods should be allowed to dry out to brown before harvesting. Approximately four weeks after harvesting, seeds can be removed allowed to dry completely before putting in a glass jar. These seeds will be viable for three years.
Vine crops are a bit more complicated, Johnson said. For instance, the temperature affects the sex of the flowers the plant produces. At first, males bloom. Then males and females bloom in midsummer, turning to only males again later in the year. She discussed the full procedures for all of these vegetables as well as others in her presentation. One of special note was peppers. When hot and sweet peppers cross-pollinate, Johnson said, the result will be hot peppers, as the hot genes are dominant.
Johnson's full presentation can be found on the UW-Madison, Extension, Horticulture YouTube channel. Visitors to the channel will also find several other gardening presentations from the same series of webinars.
Beckie Gaskill may be reached via email at [email protected].
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