Myths About F1 Hybrid Seeds – Are They Sterile?

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 😉