Many seed varieties available today commercially are hybrids. A hybrid is a cross between two genetically different varieties. Although different plant varieties can cross in the wild (and in your garden), special processes are used in commercial production of hybrid seeds to ensure predictable characteristics that can be produced over and over.
Plant breeders cross two varieties with desirable characteristics to create a new variety with characteristics of both parents. For example, they may cross one variety that is early with another that is resistant to a particular disease to create a new variety that is early and resistant to the disease. Breeders started experimenting with hybridization of sweet corn in the early 1900s and by the 1930s many hybrid sweet corn varieties were available with other types of hybrid vegetables following.
Commercial agriculture was also expanding during this time and breeders focused on characteristics that that were of most value to commercial operations including uniformity of color and size, faster maturity, greater yield, uniform maturity dates, durability in shipping, and disease resistance. The hybrids also tended to be stronger and have greater survival rates than the parents, called “hybrid vigor”.
Most hybrid varieties that are available commercially are called F1 Hybrids. F1 means Filial 1 and means that they are the first generation offspring of two genetically different parents. A cross of two F1 parents results in F2 or second generation hybrids. F1 hybrids have very uniform characteristics. However, seeds from F1 hybrids do not produce plants that are true to type, but instead have diverse characteristics of the grandparents. To get more seed of the hybrid variety, the original cross must be repeated. This is a labor intensive process often requiring hand pollination and so hybrid seeds are usually more expensive.
Some vegetables, such as corn, are easier to hybridize, while others such as beans, peas, and lettuce are much more difficult. This is why almost all commercial sweet corn seeds today are hybrids while there are no bean, pea, or lettuce F1 hybrids available commercially. However, many modern open pollinated varieties are crosses between two varieties. From the first generation hybrid crop, growers select plants with desired and uniform characteristics for seed to be planted the following year. After repeating this process for a number of generations, the population is stabilized and saved seed will produce offspring with the same characteristics as the parents. In many cases, an F1 hybrid is the starting point for this process.
Because hybrids combine positive characteristics of multiple ancestors and display hybrid vigor, they are often worth the additional cost, especially to commercial growers. Home gardeners may find that some characteristics that are important to commercial agriculture such as uniformity of appearance and maturity dates and durability in shipping are not important or even desirable. It is usually preferable for a crop to mature over a longer period of time in a home garden. In addition, flavor and nutrition may be sacrificed in favor of these other characteristics.