Planning Tips  Plant Life Cylces Selecting Seed Parents |
Garden Planning for the Seed Saver
There are several techniques to protect the varietal integrity of your open-pollinated seeds. While it may be virtually impossible to completely eliminate out-crossing due to wind pollination and insect pollinators, isolation by distance, time and barrier are the most accessible means. |
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Planning Tips
Distance Isolation
The most simple, and perhaps most effective, way to discourage cross-pollination is to separate interbreeding species from one another. The recommended distance varies slightly from species to species and is influenced by the types of pollinators that visit a given plant, or the likely range of pollen migration in the case of wind-pollinated plants.
The general rule of thumb to prevent anything but negligible cross-pollination is to keep interbreeders at least 1.5 miles apart. This is the general standard that commercial seed growers, or others who are seeking strict varietal purity, look for when planning their crops. For home growers who do not have the ability to create such separation, distances of 100 feet or more are generally desired to discourage interbreeding.
Time Isolation
A second means to protect varieties is through the use of time isolation, the staggering of blooms to discourage cross-pollination by insects or other pollinators. This requires careful planning on the part of the growers, as well as some knowledge and research to determine if planned varieties are interbreeders.
 Barrier Isolation
This method involves the use of physical barriers between interbreeders to prevent cross-pollination by both wind and insect. For interbreeding species, cages can be constructed of polyester netting over a frame of wood, metal or similar material, and placed over one of the varieties. Such cages can be alternately replaced and removed from two interbreeding plants that are blooming concurrently. This is often referred to as alternate day caging, and is the most common type of barrier isolation as it allows both varieties regular, if limited, access to pollinators. It is worth noting that limited access by pollinators results in limited fertilization and a slightly lower yield of seed.
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Understanding Plant Life Cycles
Plant Life Cycles: Annuals, Biennials and Perennials
Plants can go through an entire cycle of birth, growth, and seeding over the course of one, two or an indeterminate number of years. It crucial to understand a given plant's life cycle when considering it for seed saving. From a gardener's perspective, a plant's status as annual, biennial, or perennial often varies based on location or purpose. Today, many vegetables that are perennials or bienniels are grown as annuals in cooler climates. If a normally biennial plant is grown in extremely harsh conditions, it is likely to be treated as an annual because it will not survive the winter cold. Conversely, an annual grown under extremely favorable conditions may have highly successful seed propagation, giving it the appearance of being biennial or perennial. Some short-lived perennials may appear to be biennial rather than perennial.
Annuals
An annual plant is a plant that usually germinates, flowers, produces seeds, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed. Common annuals in the garden include: brocolli, cucumber, letttuce and melons. Many common annuals are members of the Cabbage and Mustard Family (Brassicaceae), and the Melon and Gourd Family (Cucurbitaceae).
Biennials
A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots (vegetative structures), then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming a rosette. Many biennials require a cold treatment, or vernalization, before they will flower. During the next spring or summer, the stem of the biennial plant elongates greatly, or "bolts." The plant then flowers, producing fruits and seeds before it finally dies. There are far fewer biennials than either perennial plants or annual plants.
Biennials grown for flowers, fruits, or seeds need to be grown for two years, and place a greater demand on the seed saver as they require an overwintering and additional growing season to bolt to flower and produce seed.
Many biennials are actually grown as annuals to produce a season's worth of root or leaf, including: beet, Brussels sprout, cabbage, carrot, cauliflower, celeriac, celery, onion, parsley, pasnip, rutabega, Swiss chard and turnip.
Perennials
A perennial plant is a plant that lives for more than two years. Perennials, especially small flowering plants, grow and bloom over the spring and summer and then die back every autumn and winter, then return in the spring from their root-stock rather than seeding themselves as an annual plant does. These are known as herbaceous perennials. However, depending on the rigors of local climate, a plant that is a perennial in its native habitat, or in a milder garden, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings or from divisions.
Examples of perennials that are often grown as annuals include tomato and pepper, while asparagus and rhubarb are two common perennials with hardy root stocks that often persist from season to season.
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Selecting Seed Parents
When scouting prospective parents for seed saving, be sure to select the fittest individuals to ensure stronger future generations. Some general guidelines to consider when selecting seed parents:
Have a clear idea of the qualities you most desire in the given crop.
This could include:
- Yield, size, color, flavor or other quality of fruit
- Time to first blossom or maturity
- Vigor, or relative fitness to other plants
- Resistance to disease, weather, insects and other inclement conditions
- Ease of germination
- Physical traits of plant including height, density, etc.
Always choose the healthiest and hardiest specimens for your collections.
Do not select plants that have been damaged or discolored due to infestation, excessive or deficient sun or water, or improper nutrition.
Consider the qualities you most value and monitor the entire growth cycle to obtain a more complete picture of the plants nature.
Although it is tempting to begin early season harvests from the plants with the earliest or more desirable fruits, it follows that the offspring of these plants will also be more desirable. Exercise patience in allowing some of your fittest plants to go to seed.
Always save seeds from more than one parent to reduce the possibility of inbreeding resulting from self-pollination and the chance of genetic deformation in subsequent generations.
This is especially important with members of the grass family (Poaceae), which are more sensitive to inbreeding depression. An exception to this rule includes Legiminosae and some members of Cucurbitaceae (Squash and Melon family), whose members can produce genetically identical seeds from generation to generation if self-pollinated.
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