Open-Pollinated, Heirloom, Hybrid, and GMO Seeds

​Open-Pollinated, Heirloom, Hybrid, and GMO Seeds

​I see a lot of confusion online about the different types of seeds that are available for purchase. Here I will attempt to clarify the differences between them, allowing you to make the best-informed decision about what types of seeds are best for your garden.

Open-Pollinated vs Heirloom Seeds

​Open-pollinated and heirloom seeds are similar in that both types of seeds can be saved year after year as long as they are grown distanced from different varieties of the same species to prevent cross-pollination (1). These seeds are genetically stable and manifest similar phenotypes (physical characteristics) when grown (1). Open-pollinated seeds arise from cross-pollination of separate plants of the same species AND variety or self-pollination from the same flower or separate flowers on the same plant (1). Self-pollinating varieties can generally be grown closer together with less risk of cross-pollination but unless you isolate the flower and hand-pollinate there is always the risk that the wind or an insect cross-pollinated for you if another variety of the same species is growing nearby (1). Tomatoes and peppers are probably the most saved seed by home gardeners, and I found that peppers are more likely to cross than tomatoes. I do not attempt to isolate my plants because I am only saving seeds for my use, and I do not mind the uncertainty of growing a possible hybrid the following year.

​Heirloom seeds are an older variety of open-pollinated seeds (1). Generally, any seed older than 50 years is considered an heirloom but that is not universally agreed upon (2). Heirloom seeds must be open-pollinated but open-pollinated seeds are not necessarily heirlooms. If you are interested in saving seeds and want to make sure the seeds you collect will grow to be the same as their parents, then you must use open-pollinated or heirloom seeds. New varieties of open-pollinated plants can be made using labor-intensive traditional plant breeding methods that involve crossing 2 varieties, collecting the seeds from plants manifesting the characteristics you are looking for, growing new plants from those seeds, and repeating for many years until you have a stable seed that produces the same type of plant year after year. Although new open-pollinated plants can take years to develop, once you have stable seeds, they can be propagated easily via saving seeds (assuming no other varieties were nearby to cross-pollinate).

Hybrid or F1 Seeds

​Hybrid seeds (also known as F1, or first generation after the cross seeds) are from cross-pollination of two genetically different varieties of the same species of parent plants (1). The usual way to create these can take years and lots of testing to determine that the phenotypes you want (characteristics such as color, disease resistance, size, etc.) are present and stable in the offspring. Because of the time it takes to generate new varieties of hybrid plants and because to make seed a grower needs to perform this cross-pollination each year (1), which is labor-intensive, is why hybrid seeds cost so much more than open-pollinated or heirloom seeds. Hybrid vigor is a phenomenon that often arises when two different plants are crossed and is one of the reasons why hybrids are so popular (1). You can save seeds from hybrid plants but there is no guarantee that the plant that grows from the saved seed will be the same as the parent. I have successfully re-grown some hybrids (but not most) from seeds that looked just like the parents so if you are willing to experiment there is no reason you cannot save hybrids. If you are not interested in experimentation, simply stick to saving open-pollinated or heirloom seeds. Importantly, hybrid seeds are NOT GMO (genetically modified organism) seeds.

GMO Seeds

​GMO seeds are developed by genetically engineering the genes from one species into another (2). This is done for a variety of reasons such as disease resistance, pesticide resistance, or increasing a desirable trait such as more nutrition. Most gardeners appear to be vehemently opposed to GMO seeds, but they may not be aware that 70% of the processed foods in the United States come from GMO ingredients (2). However, although you may be unwittingly eating GMO crops, GMO seeds are generally NOT available to the average home gardener (see update below!), they are primarily used by commercial farmers to grow corn, soybeans, canola, sugar beets, and cotton (FDA). Other non-processed foods that may be GMO in the United States include certain varieties of potatoes, apples, summer squash, papaya, and pink pineapples (FDA). Many people want to avoid every GMO crop which although extremely difficult is certainly an option. I think GMO crops and seeds need to be taken case by case. As an example, the Hawaiian papaya would likely have gone extinct due to a ringspot virus but was saved by genetically engineering a resistance gene into the plant. On the other hand, the practice of engineering pesticide-resistance genes into our commercial crops so that we can spray more herbicides on our crops without killing the crop itself is not a practice I am in favor of.

UPDATE on 02/07/24: As of February 2024, the first bioengineered seeds are available to home gardeners from the Norfolk Healthy Produce company. They inserted a purple color gene from an edible snapdragon plant into a tomato genome. This makes a very purple tomato with increased anthrocyanin, an antioxidant that gives purple vegetables their color. This tomato has been vigoroursly tested and is deemed safe by both the USDA and FDA. Because these seeds are under patent the fruit, seeds, or plants cannot be sold by anyone other than the company that developed them, they are also very expensive! If you want a very purple tomato that is non-GMO Baker Creek Heirloom Seeds is trying to bring the Purple Galaxy Tomato to market. They were supposed to be available early this year but due to production issues will no longer be available to purchase (they even featured it on the cover of their 2024 seed catalog, oops!) Hopefully seeds will be available soon! In the meantime, there are lots of other heirloom and open-pollinated purple and black tomato varieties available, try them all!

Conclusion

​I grow mostly open-pollinated and heirloom seeds (especially my tomatoes and peppers), but I will occasionally grow hybrids usually for specific reasons such as disease resistance, reduced bolting, or easier growth. I lost all my cucumber crop one year to downy mildew so ever since then I have grown at least one type of downy mildew-resistant cucumber variety along with my open-pollinated varieties. It is also possible that you can find open-pollinated disease-resistant varieties if you do not wish to grow any hybrids however in many cases disease resistance may not be as well documented, so it may take some trial and error with different varieties to find one that works. The other type of crop I generally grow from hybrid seed is broccoli and cauliflower. We tend to have large temperature fluctuations in the spring, and I grow much more consistent heads of broccoli and cauliflower with hybrid seeds than open-pollinated ones.
One last note on the “organic” seed label. Organic simply means a seed was grown under organic conditions as defined by the USDA’s National Organic Program (1) This means that any fertilizer, pesticides, or any other treatment used to grow the plants must all be labeled organic, and the seeds cannot contain any genetically modified genes. There is no difference genetically between a seed of the same species and variety that was grown organically versus one that was not. You can purchase organic hybrid seeds just like you can purchase non-organic heirloom seeds.

References

1. https://www.johnnyseeds.com/about-us/about-our-seed/about-our-seed.html
2. https://ucanr.edu/blogs/dirt/index.cfm?tagname=GMO
   
3. https://www.fda.gov/food/agricultural-biotechnology/gmo-crops-animal-food-and-beyond