The terms "hybrid," "heirloom," and "genetically modified (GMO)" get tossed about a lot today and nowhere more so than in the garden—specifically, the vegetable garden. In agriculture, the terms refer to how the plants are reproduced: whether by simple seed saving, cross-pollinating two different species, or introducing foreign genes. None of these methods are easily labeled good or bad and you won't find much agreement on which is the best, either. Heirlooms are plants that have stood the test of time, hybrids are often more disease-resistant or higher-yielding, and GMOs although still the subject of many studies, can be lifesavers. Each has its pros and cons.
What Type of Vegetable Seed Should You Choose?
How can you be sure that the hybrid vegetable seeds you grow aren't genetically modified? Would you be better off sticking to heirloom vegetables or are they modified, too? Here's a breakdown of each type of seed.
Heirloom vegetables are not a special species of plants. The term heirloom vegetable is used to describe any type of vegetable seed that has been saved and grown over many years and is passed down by the gardener that preserved it. It has a provenance, of sorts. To be capable of being saved, all heirloom seed must be open-pollinated, so that the plant will grow true to seed.
Open-pollinated—or OP—plants are simply varieties that are capable of producing seeds that will produce seedlings just like the parent plant. Hybrid plants do not do this.
Plant breeders cross breed compatible types of plants to create a plant with the best features of both parents. These are called hybrids and many of the modern plants are the results of these crosses.
While plants can cross-pollinate in nature and hybrids repeatedly selected and grown may eventually stabilize and become open-pollinated, most hybrid seeds are relatively new crosses and seed from these hybrids will not produce plants with identical qualities.
For example, each year new hybrid tomato varieties are offered. You may see them labeled as hybrids or F1 also known as the first filial generation (first-generation hybrid) or F2 also known as the second filial generation. These may eventually stabilize, but for the moment a tomato such as the popular 'Early Girl' does not produce seeds that reliably have the features you expect in an 'Early Girl' tomato. Seed from hybridized plants tends to revert to the qualities of the parents, so tomatoes grown from seeds saved from your 'Early Girl' tomatoes might still be tasty, but not so early.
Anyone can select and eventually stabilize seeds or even hybridize new plants, but the plant and seed companies have recently begun patenting their crosses so that they have exclusive rights to reproduce the hybrids they've developed.
Genetically Modified Plants
Hybrids should not be confused with genetically modified organisms—or GMOs—which can be any plant, animal, or microorganism that has been genetically altered using molecular genetics techniques such as gene cloning and protein engineering. One example is corn that has the bacteria Bt (Bacillus thuringiensis) engineered into its genetic makeup to make it resistant to certain pests are GMO crops. Bt is a natural pest deterrent, but it would never naturally find its way into corn seed.
There are concerns about GMO vegetables, however, the American Medical Association and World Health Organization have concluded from the research of independent groups worldwide that genetically modified foods are safe for consumers. There are times when GMOs have arguably been quite positive in their impacts—such as the high-yield, disease-resistant dwarf wheat introduced by Nobel Prize Winner Norman Ernest Borlaug, which helped increase the food supplies in India and Pakistan.
Heirloom Vegetables. Clemson University Home & Garden Information Center
Hybrids and Heirlooms. Illinois Extension
What are Genetically Modified Organisms? University of Massachusetts Amherst
Bt Corn: Health and the Environment. Colorado State University Extension
Will GMOs Hurt My Body? Harvard University
Norman Borlaug. The Nobel Prize