It's a struggle, even for experienced gardeners, to choose the best varieties of vegetables. Every catalog description includes only positive information, so each one sounds wonderful. That's why it's important to read between the lines, and to do that you must be familiar with the seedsman's terminology. One of the most common words in seed catalogs today is "hybrid." Its opposite, usually unnoted, is "open-pollinated" (abbreviated OP).
For the past few years, gardeners have been flooded with information--and a great deal of misinformation--on the relative merits of hybrid and OP vegetable varieties. In some quarters, the distinctions feed a passionate debate, and of course, each point of view has its champions. Various controversies are involved, but in almost every discussion one issue inevitably arises: Which type of plant is better suited to today's home garden, hybrids or OPs?
While this is a logical question, it presupposes that one of these huge, catchall groups is either wholly superior or wholly inferior to the other. In reality, both hybrids and OPs have their merits, and both deserve space in your garden. But first, let's back up. I'd like to share with you some of what I've learned from various seed professionals regarding this controversy. Then I'll take a closer look at some specific differences between hybrids and OPs.
Open-pollinated vegetable varieties reproduce themselves in one of two ways: cross-pollination between two plants (via wind, insects or water) or self-pollination (between male and female flower parts contained within the same flower or separate flowers on the same plant). Beets, brassicas, carrots, corn and squash are cross-pollinating, and so require isolation in the field to keep varieties true. Beans, lettuce, peas and tomatoes are self-pollinating, do not require isolation and are the easiest for seed-saving home gardeners to sustain year to year.
So long as plants of an OP variety are kept isolated from different plants with which they can cross, they will produce seed that will come "true to type." In other words, the plants in the following generation will resemble the parent plants.
Many of the older strains of OPs, often refered to as "heirlooms," are not so much varieties as they are populations. In other words, individual plants within an older named variety can possess a great deal of genetic variability and may even vary in size and shape.
Up until the early 1900's, almost all cross-pollinating OP varieties represented this broad "gene pool" kind of population. But as plant breeders worked to develop new OPs, they began learning various new techniques to create more uniform varieties of plants.
A "hybrid" vegetable seed results from the cross or mating between two different varieties or "parents" of the same plant species. In the broadest sense, nearly all vegetables are hybrids, the only exceptions being plants such as beans, peas, lettuce and tomatoes that cross-pollinate only with great difficulty.
But today, "hybrid" has a narrower, legal definition: To advertise and sell a vegetable variety as a hybrid (often designated "F1," the parents must be known and its pollination controlled. Significantly for home gardeners, hybrid seeds cost a little to a lot more, and the seeds hybrid plants produce will not come true to type.
The modern era of plant hybrids began around 1900 when biologists rediscovered Gregor Mendel's studies of pea genetics. In 1917, Dr. D. F. Jones at the Connecticut Agricultural Experiment Station in New Haven learned that he could take two very unpromising corn varieties, cross them and get offspring with very good traits but nothing like either parent. In addition, the plants were clearly more vigorous than usual, and they were strikingly uniform in the way they grew.
This ability to combine desirable traits such as disease resistance and earliness in different parent lines, and then, finally, to combine them, producing vigorous and uniform offspring, gave breeders a powerful tool to reshape all sorts of plants. By the 1930's, many hybrid sweet corn varieties were available. These new varieties were all high-yielding, and some packed enough pest resistance to make corn growing practical where it hadn't been before. Today, almost all sweet corn varieties offered by seed companies are hybrids, more than for any other vegetable.
One problem that breeders faced was that the seed the new hybrids produced did not come true to type. Instead, the offspring of these very uniform hybrids showed the very diverse traits of the grandparents. So to get more seed, the breeders had to go back and repeat the original cross. When the mechanics of making the hybrid-producing cross was simple and the volume of seed produced was great, as with corn, this issue was not critical. But for crops that required slow and detailed handwork, such as tomatoes, breeders took another tack.
After creating a tomato hybrid with desirable traits, breeders would go back and "stabilize" them for several generations until the variety could reproduce itself true to type as any open-pollinated plant. This process gave us classic tomatoes such as 'Marglobe' (1935) and 'Rutgers' (1937). Initially products of hybridization, these varieties are now considered to be open-pollinated and are treated as such.
According to John Navazio, a Ph.D. and former plant breeder for Garden City Seeds, many modern OPs are in fact "true-breeding hybrids" such as the tomatoes mentioned above. A more recent example is the 'Peacevine' cherry tomato introduced several years ago by Alan Kapuler, research director of Seeds of Change. He started with the popular hybrid tomato, 'Sweet 100', then selected and stabilized it over several generations. More recently, he has continued to grow out and stabilize other true-breeding OP varieties from commercial hybrids, such as the new 'True Gold' sweet corn.
It is all too easy to make hasty, and usually erroneous, claims concerning hybrids and OP varieties. As every gardener knows, the way different plants grow relative to one another depends upon a wide range of variables, including the vitality of the seeds, the structure and fertility of the soil, the seasonal weather conditions, the local climate and the skill (or luck) of the grower.
Still, we can draw some useful parallels between hybrids and OPs. The following sections briefly cover some of the more important qualities that gardeners (and seed companies) look for in their vegetable varieties, then compare hybrids and OPs to see how they stack up against each other.
One of the chief claims made for hybrids over OP varieties is their superior vigor or growth. The offspring of two different plant varieties often exhibit this increased vitality, which is known as heterosis or, more commonly, hybrid vigor. (The term was coined by Charles Darwin in the 1800s.)
John Navazio maintains that hybrid vigor can prove especially valuable to gardeners who live in extreme climates. "The seeds emerge more vigorously and uniformly," Navazio says. "They are stronger, and the plants perform better under a wider range of adverse climatic conditions."
Although Garden City Seeds is committed to breeding new OP varieties and making them available to gardeners, Navazio values certain hybrids, too, for what he calls their "resiliency and instant adaptability." The difference between hybrid and OP vigor, he says, appears most strikingly in specific regions of the country like the Pacific and Mountain states and northern New England, where early-season cold snaps can slow the growth of heat-loving vegetables. In such conditions, many OPs will go into a "holding pattern," but the increased vigor of hybrids helps them grow through the unseasonable weather.
Some vegetables seem to gain more hybrid vigor than others. In the case of broccoli and sweet corn, the advantages of hybrid vigor are readily apparent. For other plants--like squash, melons, cucumbers and tomatoes--the difference between hybrid and OP vigor is generally less noticeable.
According to Burpee's chairman, George Ball, Jr., "The Burpee customer puts a premium on yield." Hybrid vigor, Ball maintains, can translate into double the yield over OP varieties in the case of some vegetables. And higher yields per plant are crucial for people with smaller gardens, something that Ball sees as a continuing trend.
For gardeners who do have plenty of growing space, getting the maximum yield per plant may be less important than other, less tangible, qualities like taste and uniqueness. A lot depends on your individual needs and expectations. Some gardeners would swear by a favorite heirloom tomato that produced only six or eight ripe fruits per season. Others would be more likely to swear at it.
Disease resistance is a major concern for growers and home gardeners alike. Rob Johnston, Jr., the founder and chairman of Johnny's Selected Seeds, admits that "it's much easier to breed disease resistance into F1 hybrids than it is to breed it into an OP variety, where many genes may be involved in disease resistance." However, Johnston adds, "microorganisms, especially bacteria, are pretty clever, and they can eventually find a way around single-gene resistance in hybrids."
Many in the seed trade see the growing interest in heirloom vegetables as a step backward, toward more disease-prone varieties that are inferior to modern hybrids. It is true, especially in the case of vegetables like cucumbers and tomatoes, that hybrids offer better disease resistance than older varieties. Yet many modern OP varieties also have impressive disease resistance. The Marketmore series of cucumbers developed by Dr. Henry Munger at Cornell is one example.
Hybrid seeds are invariably more expensive than open-pollinated seeds. The price difference has to do with, among other things, the costs of creating hybrids and maintaining breeding lines. Also, a company that develops a hybrid can charge a little more for the seed because the firm has exclusivity and because it is difficult or impossible for gardeners to save seed from an F1 hybrid.
Many people gladly pay a premium for hybrid seed--typically anywhere from a few cents to a dollar or more per packet--because seed companies advertise hybrids as high-yielding, surefire varieties. But the proof is in the growing. Set up your own head-to-head trials and decide for yourself whether the hybrid's performance justifies its higher price.
Fans of heirloom vegetables like to point to their superior flavor. But a much more useful distinction can be made between OPs and hybrids that have been developed specifically for home-garden use and those earmarked for large-scale growers. Breeders who specialize in vegetables for factory farms and food processors tend to focus on qualities other than flavor. Therefore, almost any home-garden vegetable--whether hybrid or OP--will almost certainly taste better than something that has been trucked to your supermarket from California, Florida or Mexico. Beyond that, the question of hybrid versus OP flavor is strictly a matter of personal preference. And taste, as we all know, can be highly subjective. A tomato that sends one gardener into ecstasies of delight may leave another unimpressed.
Which are the best kinds of seeds to plant, hybrids or OPs? Perhaps the most useful answer comes from Rob Johnston. His advice is to look beyond labels: "The consumer in me wants settled-down varieties," he says, "ones that might not have the power of the most vigorous hybrids but that grow well enough. It's like asking how powerful a car you need or how much money it takes to be rich. The best varieties have a certain vitality, which involves complex combinations of genes. Home gardeners, Johnston advises, should be open to growing any plant that looks interesting to them."
Ideal for seed savers because they come true to type, all of the following have superior qualities for home gardeners and richly deserve their popularity. While not an exhaustive list, these are some of my favorites.
Bean, Pole -- 'Kentucky Wonder' (1850's). The most popular and widely available pole bean; early and rust-resistant.
Beet -- 'Detroit Dark Red' (1892) is still the most widely grown OP beet: roots are solid, sweet and tender. Early Wonder (1911) is one of the best for "bunching" thanks to its tall, flavorful greens.
Cabbage -- 'Early Jersey Wakefield' (1840's). An American heirloom, it remains one of the earliest and sweetest of the pointed-head types.
Carrot -- 'Scarlet Nantes' (1870) is the classic American form of Nantes that has set the standard for crispness and flavor for many years. 'Red-Cored Chantenay' (1929) is another truly American carrot (transplanted from France in the late 1800's). Its roots are mild and sweet, becoming sweeter in storage.
Cucumber, Pickling -- 'SMR 18' (1959). This is the first pickler to have resistance to both scab and mosaic plus great shape.
Cucumber, Slicing -- 'Marketmore 76' (1976). A high-quality slicer for the North, it also has disease resistance and excellent fruits.
Eggplant -- 'Black Beauty' (1902). Introduced nearly a century ago and still a superior and widely grown home-garden variety.
Lettuce -- 'Black Seeded Simpson' (1850). Early, adaptable, takes heat and some drought. One of the oldest varieties and as popular today as it was 150 years ago.
Melon -- 'Iroquois' (1944). The first commercial variety with fusarium wilt resistance; its earliness makes it reliable for gardeners in the North.
Pepper -- 'California Wonder' (1928). Though several strains are available now, the original still produces well-formed, blocky fruits that are ideal for stuffing.
Spinach -- 'Bloomsdale Long Standing' (1925). Glossy, dark green, heavily savoyed leaves are tender and flavorful; vigorous, slow-bolting plants.
Squash, Summer -- 'Early Yellow Crookneck' (circa 1700). Listed in catalogs as early as 1828, it is still by far the tastiest of all yellow squashes, though low-yielding compared with newer hybrids.
Squash, Winter -- 'Buttercup' (1932). A tour de force of 20th-century winter squash breeding, it's a quantum leap forward in sweetness and quality.
Tomato, Fresh -- 'Brandywine' (1885). An Amish heirloom that has become the standard bearer for heirloom tomato lovers in recent years.
Tomato, Sauce -- 'Roma' (1955). Widely grown for its good, solid, meaty quality that's perfect for sauce.
For a hybrid to last longer than 10 years in the marketplace is a testament to its greatness. The following hybrid vegetables, a sampling of favorites, have become home-garden classics.
Broccoli -- 'Premium Crop' (1975). Hybrid broccolis come and go, but this one always performs well and has a fiercely loyal following.
Cabbage -- 'Stonehead' (1969). Truck farmers sing its praises, and home gardeners who make sauerkraut ask for it by name.
Cauliflower -- 'Snow Crown' (1975). Forms perfect white heads with little or no "buttoning," bolting prior to head formation.
Corn -- Several must be mentioned: 'Early Sunglow' (1956), 'Golden Cross Bantam' (1934), 'Illini Xtra-Sweet' (1971) and 'Silver Queen' (1960). Corn is the success story of the hybridization process.
Cucumber -- 'Sweet Success' (1983), Becoming more popular every year, its fruits have thin skins and sweet flavor.
Eggplant -- 'Dusky' (1975). Still the most reliable eggplant for northern gardeners.
Melon -- 'Ambrosia' (1975). Distinctive color and flavor; sweet, juicy, and widely adapted. After 40 years, 'Burpee Hybrid' (1955) is still among the best for gardeners in short-season regions.
Pepper -- 'Gypsy' (1981). Early, prolific, and tasty.
Squash, Summer -- 'Sunburst' (1985). After only 10 years, this patty pan has become the standard of its type. The bright yellow fruits are a fixture at farmer's market.
Squash, Winter -- 'Sweet Mama' (1979) is the most reliable and best-yielding of the sweet Japanese kabocha types. Acorn-type 'Table Ace' (1976) gains new fans every year.
Tomato -- Always hard to pick a favorite: 'Burpee's Big Boy' (1949) may be the longest-lived tomato hybrid on the market. 'Celebrity' (1984) and 'Early Girl' (1975) are bona fide classics.
Ben Watson is the author of Taylor's Guide to Heirloom Vegetables (Houghton Mifflin Co., 1996; $18), and Gardener's Supply Company Passport to Gardening : A Sourcebook for the 21st-Century Gardener (Chelsea Green Co., 1999; $20). He lives in Francestown, New Hampshire.
Photography by National Gardening Association.
Article published on June 23, 2008.