About Seeds

Seeds are at the heart of vegetable gardening, yet many gardeners misunderstand the realities of how, where, and why seed is grown, and even more, the effect that seed selection has on harvest results. There have been enormous improvements over the years in the quality and variety of vegetable seed, and while home gardeners have benefitted from all this, they are not very important overall.  About 90 percent of the seed sold in this country every year is for field corn, soybeans, grain, and grasses:  for pastures, lawns, gold courses, and parks (not to mention reclamation of land stripped for construction, mining, or roadways).  What’s more, the major buyers of 90 percent of that last 10 percent are not home gardeners, but vegetable farmers, who plant thousands of acres per year.

This market reality affects the seed available to us.  New vegetable varieties are generally bred for the commercial growers, who know the value of good seed and are willing to pay a premium for it.  Many of the characteristics of these improved vegetable varieties are great for home gardeners, too:  enhanced yields, disease resistance, etc., and the quality of this new seed is very high.  Other aspects, though—like uniform appearance, at the expense of flavor, and shipping tolerance at the expense of good texture—are in direct conflict with the needs of home gardeners.  So the wise gardener will balance these two aspects when choosing which varieties to grow.

The breeder also is forced to balance different objectives when developing a new vegetable variety.  Improvement of a domesticated plant (or animal) begins with a list of desired characteristics; then follows with propagation of individual plants that exhibit the desired traits.  What happens in practice is that trade-offs must be made between, say, disease resistance and flavor, uniformity of color and taste, plant habit and yield.

No variety is perfect for everybody.  A vegetable bred for commercial growers in one region need not be adapted to grow anywhere else in the world.  A single large California broccoli grower, for example, may use more seed of a given variety over the course of a season then even the largest of our mail order home garden seed companies!  But a variety bred for home gardeners, on the other hand, must grow as well in the desert Southwest as it does on the foggy Maine coast—even if attaining this wide adaptation requires the breeder to put aside other desirable traits—because only then will it sell well enough to offset the cost of its development.

There is, of course, some cross-over among categories.  Small market gardeners often grow home garden and processing vegetables to sell direct from a farm stand, because the quality of their produce is more important than shipping ability.  Home gardeners often do a significant amount of freezing and canning, and so grow varieties suited to once-over harvest.  But on the whole, it is a good idea to figure out what a particular new variety was originally bred for.

Another group of vegetable varieties to consider is those which pre-date the current seed production and food distribution systems we have in this country—called heirlooms.  The current definition of an “heirloom vegetable” variety is one that is more than 100 years old.  But I think that a better cut-off point would be 1950.  Immediately after World War II, agriculture and gardening in America underwent enormous changes, and the current system was born in that period.  The widespread adoption of chemical fertilizers and synthetic pesticides, the development of hybrid vegetables, the completion of rural electrification, improvements in refrigeration and our interstate transportation system, suburban destruction of urban fringe market gardens—all these changes became part of a trend that resulted in the national rather than regional scope of our mass culture and agriculture.

Before this current period, vegetable seed companies were smaller and often grew their own seed, regionally adapted to the climate of the area in which the company was located.  In fact, many seedsmen started out as market gardeners, and simply moved into selling seed they had saved for their own use.  As their businesses developed, they collected choice varieties from other gardeners—who had selected their own favorite strains—and by close attention maintained them as distinct varieties.  Unlike modern vegetable introductions, all of which are deliberately developed for sale, these heirloom varieties were simply selected over generations according to the whims and preferences of individual gardeners.  Thus most are strongly adapted to a particular region of the country, and have an incredible range of qualities—in taste, texture, appearance, and disease or pest resistance—all of which were, for one reason or another, important to their backyard developers.

Of the thousands of regional heirlooms a relatively small number eventually became standards; many of our modern hybrids owe part of their parentage to them.  Some of these old standards are still available today, though the re-selection and propagation of any variety subtly changes its nature over time.  Early Jersey Wakefield cabbage, Bibb lettuce and Rutgers tomato are three that come to mind immediately.

Open Pollinated Seed

You may have noticed the mention of open-pollinated and hybrid seed in the discussion above.  Unfortunately, many gardeners don’t understand the distinction, or the differences, in both seed cost and garden performance related to this.  Some organic gardeners think that it means, in essence, that one is organic and the other is not, which is not at all a relevant distinction.

To over-simplify the matter, let’s say that there are two basic ways that seed comes to be formed on a plant:  self-pollination and cross-pollination.  Pollination is the transfer of pollen (a plant’s version of sperm) from an anther to the stigma of a flower, where it can fertilize the flower’s egg.  In self-pollinated plants the whole process happens within the flower.  Lettuce flowers, for example, pollinate themselves, as the female part of the flower containing the egg, in the process of opening, passes through an encircling ring of pollen-laden anthers.  In cross-pollinated plants the pollen comes from an entirely different flower, or even plant, of the same species, transported by wind or the visitation of insects or other animals.

Open-pollination means simply that the plants are left to become pollinated (if possible) on their own, naturally.  To say that a vegetable variety is open-pollinated, however, implies more than that; it implies that the variety will “breed true,” that is, its offspring will resemble itself in all important particulars.  After all, to call a kind of plant a variety (properly, a cultivar) is to recognize that it has a particular set of identifiable characteristics, of the kinds we’ve discussed above:  yield, appearance, disease resistance, nutrient content, etc.

In a self-pollinated vegetable, open-pollinated seed will produce 90 percent or more offspring that are true to type, because virtually all the pollen comes from the same source as the egg, and so the possibility of new genetic traits becoming established is small.  But cross-pollinated plants—unless the parentage can be controlled in some way—will not maintain their identity. That is, the set of characteristics that defines a variety, and which we gardeners seek to maintain, are in a constant state of flux; that is ideal in terms of their own need to adapt to their environment, but of little use to the gardener, who wants predictable characteristics.

Largely self-pollinated plants like lettuce, beans, peas, tomatoes (and to a lesser extent peppers and eggplants) are fairly easy to maintain, because it is their natural tendency to remain as distinct varieties once they are established as such.  Cross-pollinated plants like spinach, beets, carrots, corn, and the onion, cabbage, and squash families require more attention.  An established variety must be grown in total isolation from other members of its “breeding family,” so that there can be no cross-pollination from outside the variety itself.  Otherwise a fairly high percentage of offspring in the next generation will have traits untrue to the nature of the variety, though the fruits of the current crop will not show the differences.

 Hybrid Seed

Hybrids are not varieties in the above sense, as they will not breed true, that is, produce another generation of plants completely like themselves.  The seed from a hybrid tomato, even though self-pollinated, will produce a grab bag of types, of which a quarter will resemble the hybrid’s male parent, a quarter will resemble the hybrid’s female parent, and half will display various combinations of the two parents’ genetic traits.  Eventually, after half a dozen generations or so, any of these offspring, could, by self-pollination, become distinct varieties themselves.  If they exhibited especially valuable traits, they might be worth maintaining as such.

In fact, this is how most new varieties of vegetables are created:  the breeder takes two plants which have characteristics of interest, crosses them, and in future generations looks for individual offspring that have the proper combination of the desired traits.  He or she then attempts to bring those individuals to a state where they breed true, then perhaps crosses them with others developed the same way, until a whole range of desirable features has been bred into one plant or group of plants, and the traits of the new variety stabilized.

But back to the hybrids themselves:  the first generation (hence the designation F-1 we see in catalogs) of a particular controlled cross-pollination will exhibit what is called “hybrid vigor”—a sort of snyergistic increase in the vigor of a plant due to the combination of widely diverse genetic traits—and great apparent uniformity (though its own offspring, the F-2 generation, will belie this).  Since both vigor and uniformity are desirable to breeders (and to commercial vegetable farmers) the production of hybrid seed has been aggressively pursued since it was first developed as a method of improving corn varieties in the first half of the 20th century.

The two keys to successful and profitable hybrid seed production are

  • (1) maintenance of pure parent plant lines which, when crossed, will produce a hybrid of particular, desired characteristics, and
  • (2) economical methods of making the cross-pollination to actually produce the seed.

While naturally self-pollinated plants are relatively pure to begin with, and need only be grown out to check on their uniformity, cross-pollinated plants are more time-consuming to work with.  It may take years to breed sufficiently pure parent plants, and significant hand work is involved.  To be absolutely sure that the parent lines are kept pure, each flower may need to be pollinated by hand and its resultant seed collected, cataloged, and replanted.  Then, once the parent plants are ready to cross for production of the F-1 hybrid seed that you, the gardener buy, attention must still be paid to ensure that they cross with each other, rather than with themselves or some other, unknown parent.  All this means that hybrid seed is expensive to produce, and so the price of the seed is bound to be higher as well.  The higher price is usually worth it, though, due to higher yields, uniformity, and other traits, like disease resistance.

This higher cost of production is offset, in the mind of the seedsman, by a different, and very important factor:  since the hybrid plants that result do not themselves breed true, the gardener or farmer who bought the seed must return to the seedsman each year for more of the original hybrid seed.  Further, the seed can be produced only by crossing the two parent lines, which are the sole property of the seedsman who developed them, and the parents are likely often known only to him.  The “natural monopoly” which results means that if a given variety is demonstrably superior, the seedsman can make a very handsome long-term profit on the sale of hybrid seed.

Thus in a technical sense, there is no difference between hybrid and open-pollinated seed in terms of organic gardening.  Functionally though, there is, because as seedsmen stop maintaining open-pollinated lines to concentrate on their own private, pure lines to be used for hybrid production, diversity—at least publicly available diversity—declines, and diversity is one of the underpinnings of the organic method.  Plants like lettuce, beans, and peas may never suffer this fate because they are not economic to produce as hybrids.  But even there, the drive toward mass production of a limited range of varieties works toward limiting diversity.  What this means is that there is a natural alliance among seed exchanges, small seed companies, and organic gardeners to favor open-pollinated vegetable varieties, and to maintain heirloom strains, even though the short-term performance of a particular hybrid may be superior.

Just as many of us who began in the organic agriculture movement have worked over the last decade to learn the skills necessary to build a new food system, there are people working toward the same goals in the seed industry.  Within another ten to twenty years we will have the intellectual infrastructure that drives the development of new materials and methods of gardening and agriculture. At that point an organic seed industry will exist along with all the other support structures of an organic horticulture.  Your dollars and your demands do (and will) make a difference.

ShepherdAbout Seeds

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