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By Luke Sumpter Reviewed by: Andreu Francés

What are F1 hybrid cannabis seeds? How do they compare to other strains? And what makes them so revolutionary within the world of weed? Below, you’ll find out exactly how they’re made, what benefits they offer, and why most growers likely won’t go back to conventional strains after trying F1 hybrid cultivars.

What Are F1 Hybrid Cannabis Seeds?


F1 hybrid cannabis seeds are created by crossing two heavily inbred parent lines. As a result, these varieties are more resistant to disease than traditional cannabis strains, more uniform, and produce larger yields.

The term “F1” stands for “filial 1”, which describes the first generation of progeny between two inbred lines. … Unlike breeding conventional strains, inbreeding results in offspring that possess excellent uniformity and more desirable traits. The three terms below will help you further understand the concept of F1 cannabis hybrids.

Heterozygosity and homozygosity


Much like us humans, cannabis plants inherit a pair of chromosomes from their parents that contain many genes and dictate their biological traits. Each gene can present alternative forms or expressions—called alleles. Heterozygosity occurs when a particular gene presents two different alleles.

For example, let’s say that a cannabis breeder crosses a plant that exhibits a purple colour with plant that exhibits a green colour. The heterozygous offspring will inherit two different alleles that code for colour; one that codes for green (higher chlorophyll expression) and one that codes for purple (higher anthocyanin expression). Therefore, these plants will be heterozygous, since they contain two different alleles. When a heterozygous plant is crossed with another plant, some specimens will inherit the allele that makes them green, and others will inherit the allele that makes them purple, giving rise to a generation of unstable plants.

This is an oversimplified example, as environmental factors also play an important role in plant colour, but it gives you an idea of how regular crossbreeding works.


Homozygosity describes the opposite. Instead of inheriting two different alleles that code for a different trait, plants inherit two alleles that code for the same trait (one from each parent). Using our example of colour, if a purple hue is what the breeder desires in the offspring, the plants will be bred to inherit the gene with the same alleles that both code for a high concentration of anthocyanins. Therefore, the offspring are more stable in the sense that they will consistently display a purple colour.

As you can imagine, producing homozygous plants means that breeders and growers can secure a more uniform and stable crop, and thus achieve more consistent and desirable results.

Hybrid Vigour (Heterosis)


Although the process of inbreeding produces highly consistent and stable genetics, it eventually results in inbreeding depression. This phenomenon describes a reduction in crop vitality, performance, and resistance. However, crossing plants from two different inbred lines (IBLs) revitalises the genetics within the progeny. Known as hybrid vigour (or heterosis), this phenomenon refers to the boost in biomass, disease resistance, and productivity displayed by F1 hybrids.

How F1 Hybrid Seeds Are Created

The beginning of the F1 hybrid breeding process starts out with formulating an idea of what the breeders want to develop. From here, they set certain goals, and will spend the duration of the project teasing out and fixing the desired traits in the parent IBLs.

For example, one breeder might decide that maximum cannabinoid and certain terpene concentrations are the priority, while another team might aim to create a small and compact but productive F1 suitable for stealthy indoor growing. Of course, genetics that are highly resistant to certain pests and diseases are also highly valued. However, to achieve any of these desired end results, breeders must start out with strains that show great promise.

How are F1 Seeds Created?

1. Parent Selection

After deciding on their end goal, breeders must seek out strains that display at least some of the traits they’re looking to express in the progeny. For example, selecting a highly potent cultivar will help in creating an F1 cannabis hybrid with high levels of THC. This same rule applies to any trait—be it convenient size, productivity, resistance to diseases and pests, trichome density, colour, plant structure, and low sugar leaf production. In other words, you can only optimise traits in the progeny that already exist in the parents.

2. Developing Inbred Lines (IBLs)

Of course, it takes two parent strains to create a progeny. Crossing two specimens from two different IBLs will create a uniform generation of F1 hybrids that exhibit a blend of traits from both parents. However, in order to endow an F1 with hybrid vigour, breeders must cross two genetically distinct IBLs in order to reverse inbreeding depression in the offspring. Therefore, breeders create two separate IBLs and focus on developing separate traits in each. For example, they may hone in on colour and size in one IBL while doubling down on disease resistance in the other, before crossing a male and female from distinct IBLs.

Where Are The Limits of F1 Hybrid Breeding?

F1 hybrid cannabis varieties are the most advanced genetics available to growers; nothing else rivals their potency, productivity, and uniformity. However, there are limitations when creating these cultivars. Breeders won't be able to create new F1 hybrids with wacky colours that aren’t currently found in cannabis, or outrageously high THC and terpene quantities that plants simply aren’t capable of biosynthesising. Adding to this, breeders can’t genetically manipulate plants to develop new growing patterns that are only achievable through training techniques such as topping and LST.

F1 Hybrid Seeds vs Traditional Strains

If you grow cannabis and frequently visit online seed banks to procure seeds, you’ve probably come across the term “hybrid” well before the advent of F1 genetics. You’ve likely also come across breeders that labelled their strains as F1, F2, F3, and so on. While these varieties are technically hybrids, they’re much different than true F1 cannabis hybrids. Virtually all of them stem from unstable parents, which makes them cannabis strains. 

Compared to true F1s, polyhybrids possess much more genetic variability, which means the progeny display a relatively wide range of traits. Because they don’t descend from IBLs, they also lack hybrid vigour. Check out the key differences between F1 hybrid cannabis seeds and traditional strains below.

1. Performance

F1 hybrid cannabis seeds guarantee superior performance. Unparalleled uniformity means you can rest easy knowing that every seed you pop will develop into almost identical phenotypes that share the same size, structure, quality, resistance, and phytochemical profile.

Traditional strains, in contrast, are more of a genetic roulette. Sure, you’ll have a common genetic thread that runs through each plant, but each individual phenotype will differ—even if they come directly from the same parents. Additionally, strains are more prone to diseases and don’t produce consistently large yields.

2. Breeding Process

The breeding process that underpins traditional cannabis strains varies depending on the breeder. Some start with relatively stable heirloom genetics, whereas others kick things off with highly genetically unstable strains. Some breeders make the effort to “pheno hunt” and backcross in order to stabilise their genetics as much as possible. However, no strains on the market match the stability of true F1 hybrids. The latter possess this trait because of the intensive inbreeding required to create them.

Genetic Purity F1

F1 Hybrids in Traditional Horticulture

Professional horticulturalists, farmers, and hobby vegetable growers have had access to F1 hybrid crops for decades. Next time you step into a supermarket, take a second to notice how uniform all of the tomatoes, carrots, watermelons, and squashes look; they’re all F1 hybrids! Why? Because it makes financial sense for growers to cultivate the most uniform, resistant, and productive plants possible. Before the advent of F1 crops, growers had to settle for unstable and unproductive cultivars, or genetically stable heirloom varieties that didn’t present valuable traits for growers.

✅ The Benefits of F1 Hybrid Crops

For most farmers and gardeners, opting for F1 hybrid genetics is a no-brainer. They’re less likely to fall prey to diseases and pests, produce more biomass, and their excellent uniformity prevents the occurrence of poorly performing individual plants from impacting overall yield.

❎ The Downsides of F1 Hybrid Crops

Commercially, F1 hybrid crops reign supreme. However, they do have a downside. Many home gardeners, and even niche market farmers, prefer to sow and grow heirloom varieties, as it allows them to save seeds from their crop and sow them again the next year. These seeds grow true to type, and eventually adapt to the local climate. In contrast, growers can’t save seeds from F1 hybrid crops; they simply don’t grow true to type and will start to express high genetic variability in the F2 generation.

The appearance of F1 Hybrid Seeds

The physical appearance of F1 hybrid seeds can be affected due to the inbreeding depression of the inbred lines. Some F1 Hybrid seeds may exhibit small, open or cracked seeds. However, it is important to note that this issue will not affect the germination and proper development of the plant.

F1 Hybrid Cannabis Seeds: The Final Frontier

Farmers and gardeners have used F1 hybrid genetics to obtain better harvests for years. The introduction of these genetics into the world of weed means growers now have a whole new set of varieties to choose from, including photoperiod and auto F1 hybrid varieties. Add these seeds to your arsenal, grow them out, and see for yourself just how F1 hybrids compare to traditional strains.

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