Every once in a while, we garden educators will break out into a rash of definitions, especially after hearing people toss words around without entirely understanding them. I'm getting the itch right now, so here's my effort to define some commonly used gardening terms.
- Hybrid. In basic terms, hybridization is the crossing of two different species or varieties of plant, which can occur naturally; but when you see "hybrid" or "F1" in a catalog, it means that the seed has been produced by human intervention, by bringing the pollen from one plant to another in a controlled fashion to purposefully create or emphasize certain characteristics, such as disease resistance, flavor, size, or early harvest. Hybrid seed can be a good choice if these characteristics matter to you - for example, if you have a regular problem with cucumber mosaic virus, you'll want to choose plants that have been bred to be resistant. It usually costs more than open-pollinated seed, and you'll have to buy it again every year (or when your packet is empty). F1 hybrid plants do not produce stabilized seed; if you save seed from them and plant it, the resulting plants will likely have a different mix of characteristics from the F1's parent plants. I've done this inadvertently, especially with hybrid cherry tomatoes such as Sun Gold - the fruit falls before it can be picked, and next year you get some volunteer seedlings that might be orange cherries that don't taste quite as good, or tiny little red fruits on a ridiculously vigorous vine, or something else entirely.
- Open-Pollinated. Open pollination means that pollen is transferred by means of natural mechanisms, such as wind or insects. Some plants self-pollinate, meaning that the pollen moves only from one flower to another (or within one flower) on the same plant, and some cross-pollinate, meaning that pollen will easily move from one plant to another of the same species. There are many subcategories and a lot of wiggle room within this, but let's not get too complicated. Just know that if you're growing beans, peas, tomatoes, lettuce, and a few other species, self-pollination is the most likely thing to happen, and with many other vegetable species, cross-pollination can occur, which means that if you want to breed true-to-type seed, you need to keep different varieties of the same species isolated. If you manage this, and plant the resulting seed, you'll get plants very similar to the parent, because open-pollinated seed is stabilized. They will not, however, be genetically identical to the parent, because this doesn't happen in natural reproduction. Open-pollinated seed usually maintains a fair amount of genetic diversity.
- Heirloom. All heirloom plants are open-pollinated, but not all open-pollinated plants are heirlooms. There are different definitions for "heirloom," some of which rely on how old the variety is (say, more than 50 years), and some of which talk about the seed having been passed down in a family or community.
Therefore, by our usual definitions, hybrid and open-pollinated are the two major categories of seed and plants, with heirlooms being a subcategory of open-pollinated. It's possible for hybrid varieties to be bred until they achieve stabilization and are considered to be open-pollinated. Some people consider older commercial open-pollinated varieties to be heirlooms, so you could have a hybrid variety become an heirloom, given time and a lot of breeding work. It's important to understand that nearly all garden varieties of plants result from some human intervention along the way, whether it's in a commercial facility, a farmer's field, or Grandma's back yard. We tend to want certain characteristics in our vegetables and flowers, and to select for them; this is artificial rather than natural selection (to our benefit, not the plant's), but it's still a long-term process involving the plant's natural method of reproduction.
- GMO. A genetically modified organism, on the other hand, is created by implanting genes from one species (plant or animal) into another species whose DNA would not normally contain them: lab work, not field breeding, done for a specific purpose that in theory improves the resulting species. GMO seed can be hybrid or open-pollinated. This process is still controversial, but has made a lot of plants easier to grow. We can support or condemn the method as consumers or as farmers, but as home gardeners it's pretty much irrelevant to us: if you wanted GMO seed for your own garden, you'd find it hard to get hold of. It's just not sold in the catalogs we use. (Note: this is not the same as saying that no home garden seed purchases will benefit companies that do sell GMO seed. This is a separate issue that you can address as a consumer.)
I hear a lot of confusion out there between hybrids and GMO plants, and between non-organic methods and GMO growing. Just because you use hybrid or non-organic seed, or use chemical fertilizers or pesticides on your garden, you are not "a GMO person." We have a lot of choices in gardening, as we do when we shop for food, and make them for personal reasons. Some of us may not want to buy food made from GMO products because we're uncertain of their effects; some of us may want to grow heirloom plants because we love history or think the flavor is superior; some of us may feel we need to discourage severe outbreaks of insects with pesticides (after educating ourselves about their use, and trying less aggressive solutions); some of us want the relative security of a hybrid variety that is known to resist a common disease or produce reliably before the end of the season. I'm not going to discourage anyone's choices, but I do think it's important to make the choices based on good information and understanding of what the words we use actually mean.