There seems to be a lot of confusion about F1 hybrid seeds. Here is the truth about some common myths.
What are F1 Hybrid Seeds?
F1 stands for “Filial 1“. It is the first generation of a cross between two parents. You are the F1 offspring of your parents. When this F1 generation interbreeds (i.e. you with your siblings) it will form the F2 generation, and so on. The term “F1” is used for any cross even if it is not a hybrid.
The word hybrid is added to indicate the cross was between two distinctly different parents. In biology, a hybrid is the offspring resulting from two different varieties, subspecies, species or genera. In the gardening world, the term hybrid is usually used for crosses between different, but very distinct cultivars, also called breeding lines.
F1 hybrid seeds are the seeds produced by a F1 cross and F1 hybrid plants are the result of germinating such seed.
For example, when you cross shelling peas (Pisum sativum) with snow peas (Pisum sativum v. sachhamatum) you get sugar snap peas. Sugar snap peas are hybrids that have now been line bred to form a stable cultivar and some people even call it a heirloom.
My favorite cherry tomato is the Sweet 100 which is an F1 hybrid of two tomato lines who’s identity is closely guarded, but some believe Gardener’s Delight is one parent.
Many gardeners and seed companies drop the F1 designation and just use the term “hybrid” to mean F1 hybrid. Anyone talking about “hybrid seed” is probably talking about “F1 hybrid seed”.
My background is in biochemistry, DNA studies and genetics, so I feel quite confident writing about the following myths, but if you disagree, please post a link to correct information in the discussion below.
Myth 1: F1 Hybrids are Sterile
This came up in a discussion in our Facebook Group, Garden Fundamentals, and I was very surprised at such a silly claim, but it took me no time at all finding sources online that made this claim. For example this Master Gardener report said, “F1 hybrid plants may be sterile”.
It is true that in any batch of seeds, a few individual seeds may be sterile, but that is true of every cross, even in a cross of heirlooms. Except for special cases, the majority of F1 hybrid seed is not sterile.
Imagine how popular the Sweet 100 tomato or the sugar snap pea would be if the seed was sterile? Nobody would get any food from them. Why would anyone produce it or grow it?
What is Sterile Seed?
Sterile seed can mean one of two things. Either the seed will not germinate, or if it does germinate the resulting plant won’t produce fruit.
When two parents produce offspring, there is always a chance of sterility. The probability is higher with parents that are more dissimilar. Many species of the same genus are not compatible and produce sterile seed or no seed at all. Some cultivars of the same species will also produce sterile seed.
An example that many are familiar with is a cross between a horse and a donkey which produces a mule, which is sterile. Perhaps this is the information that started this myth?
Myth 2: F1 Hybrid Parents Need to be Self-pollinating
This is just nonsense. The pollination process of the parents has nothing to do with it. For example, cucumbers are not self-pollinating. They have separate male and female flowers and yet we can produce F1 hybrids such as Sweet Success.
Myth 3: F1 Hybrids Don’t Taste as Good
This is a common myth that organic proponents use to persuade gardeners to stay away from hybrids. Scientific testing shows that both hybrids and non-hybrids can have good flavor. Flavor has more to do with growing conditions and the selection of a good cultivar for the growing conditions. The right cultivar, even if it is a hybrid, will produce good tasting food.
In over 50 years I have not found a better tasting cherry tomato than the Sweet 100, until now. We really like the new GMO ‘Purple’ tomato, but it’s flavor is completely different than that of Sweet 100.
Myth 4: F1 Hybrids are Genetically Modified
They could potentially be GMO plants, but I don’t know of any that are. Hybrids have been genetically manipulated in the field using traditional breeding methods. They are not produced in the lab.
Besides, there is no need to be concerned about GMO plants.
Myth 5: F1 Hybrids Require Chemical Fertilizer
It is claimed that, “F1 hybrids are often reliant on intensive culture based around chemicals. The seed company will happily sell you some fertilizer gunk to make them grow bigger, and then some pesticide gunk to kill off anything that’s tempted to have a nibble.”
This is complete nonsense. Why would hand pollinating two established lines produce seed that suddenly requires synthetic fertilizer? Besides the nutrients from both synthetic fertilizer and organic fertilizer are identical.
Myth 6: Sweet 100 Tomatoes Produce 100 Tomatoes
Wrong – they produce more than 100 tomatoes 😉
Hi Robert,
The reason some growers disapprove of F1 hybrid seeds is because they often don’t breed true. That is because when you hybridise dissimilar varieties, the alleles (gene variants) get mixed up. In the F1 generation of plants, only dominant alleles are expressed, so the F1 plants are effectively genetically identical, which has both benefits and drawbacks, as you state. When one re-sows seeds from F1 plants, in the following F2 generation, the alleles will segregate, so one’ll get both dominant and recessive alleles expressing themselves. The F2 plants may or may not resemble the original variety. You could try growing out your Sweet 100 F2 seeds and see what happens.
I reference Rebsie Fairholm’s blog, who explains this far better than I can: http://daughterofthesoil.blogspot.com/2008/10/joy-of-mendelian-segregation.html
The RHS also has a useful page on hybrids: https://www.rhs.org.uk/vegetables/f1-hybrids
Also you say: “For example, when you cross shelling peas (Pisum sativum) with snow peas (Pisum sativum v. sachhamatum) you get sugar snap peas”. This is unlikely; if one makes that cross, all of the F1 generation will be shelling peas because the two alleles needed for fibreless pods in snow peas / mangetout are both recessive. In the F2 generation, alleles will start to segregate so one’ll get a mixture of mangetout and shelling types in about a 1:4 ratio, respectively. This is called Mendelian segregation and was my experience when I bred my own mangetout varieties. For sugarsnaps, as well as the two alleles for fibreless pods, one needs another recessive allele to make the thick, crunchy pods, so unless those alleles are present in one of the two original varieties, they won’t be present in the F1, F2 or F20 generations, and unless two copies of those allele are present, they won’t be expressed and one won’t get sugarsnaps.
Please note I’m not an expert, just a fluffy-cheeked amateur gardener with too much time on his hands! Happy days and thanks for your website. 🙂
(I apologise if you receive this twice; I messed up the email address the first time!)
I do understand that collecting F1 seed does not produce plants like the parent.
Have you tried growing ‘Sungold’ or ‘Isis Candy’ cherry tomatoes? They’re fantastic! My favorite article of yours regarding heirlooms is ‘Heirloom Seed Myths – Are They Worth Buying?’, specifically the section on ‘Do Heirlooms Actually Exist?’. After reading your article on heirloom seeds, I consider heirloom tomato varieties are simply open pollinated non hybrid varieties.
I would like clarification regarding you calling ‘Sugar Snap’ peas as being a stable cultivar. Is ‘Sugar Snap’ now considered an open pollinated type, or a non-hybrid? What is your definition of “stable cultivar”? Are some, most, or all heirloom tomato varieties stable cultivars? Will ‘Sugar Snap’ become an heirloom Thanks.
Some companies call them heirlooms even though they are not 50 ye4ars old. They are open pollinated and produce seed similar to the parents, however you do get the odd one that does not form pods correctly.
I have eaten sungold, but not grown them.
I had no idea about the difference between the terms hybrid and cultivar or that hybrids weren’t produced in some kind of professional setup. Could be all the stories about sterile seeds developed to sell more seeds the following year (boo). As usual, you have educated me and made me chuckle. Indeed, my Sweet 100s have exceeded expectations implied by the moniker.
Thanks for the info. As for your liking the new Purple tomato, I’d like to taste the ones you grew. Mine were absolutely without flavor. They grew in abundance, I loved the crunchy purple flesh, but they just didn’t taste like much at all. They were growing right next to my sweet 100’s and Roma cherries, both of which continued to delight my taste buds, so I don’t think it had anything to do with the soil or growing conditions.
“You are the F1 offspring of your parents.” Thank you, nicely put and very clear about what F1 actually means.
Another super informative and great post! I have learned more about plant and soil science from you in the last 7 months than through trial and error, plus the bits and pieces picked up over the 5 decades that I’ve been gardening; first on a hobby farm and more recently on an oversized city lot. in central British Columbia (zone 3).
‘Proof is in the pudding’, as they say and while most folks around here have cleared their gardens down to bare soil and set their bags of raked leaves out for pick up by the city’s disposal service, my gardens which occupy 80% of the property had the best year ever and are still going strong despite frosty nights and the damp, cool days of autumn.
I can’t thank you enough for enlightening me to the chop and drop method of composting during the growing season, all of the info about composting in piles and how best to use that material, application of additional mulches, your extensive advice with respect to fertilization, checking soil pH, correct watering and especially for your science-based myth busting of all those.
Thank you very much.
I used to grow Sweet 100 but these past few years, have grown Sungold F1, as I find the flavour even better.
I can usually harvest them from early June through to late October/early November here (temperate, zone 9) if we remain frost free, though the latter involves dropping the plants 2′ in early August to allow space for 2-3 more trusses.
Their only downside is the skin tends to split if watering isn’t kept consistent.
Best truss I ever had on Sweet 100 was more than 70 tomatoes – must’ve been nigh on 300 from 5 trusses (only had a small greenhouse back then)
Great explanation. I saved seed from an F1 cucumber. I intend to try growing it. I expect it to be slightly different from the parent. That is not a problem.