F1 Cannabis Seeds

Some of the most unique cannabis strains available were created by home growers; in some cases, by complete accident. Successful crosses inherit the best traits from their parents. Let's discuss what F1, F2, F3 etc selections are.

Cannabis Breeding Basics: F1 Hybrids and Beyond

Breeding cannabis can be an extremely complicated and time consuming process. In order to identify and stabilize a sought after trait, it may take multiple generations and hundreds, if not thousands, of plants. This is why most breeding operations are left to the professionals who have sizable facilities dedicated to breeding. This is not to say that basic breeding cannot be done in a cannabis hobby garden. In fact, some of the most unique cannabis strains available were created by home growers; in some cases, by complete accident.

One aspect of cannabis breeding that is different than most vegetable breeding programs is that cannabis plants are dioecious, meaning they have separate female and male plants. Most vegetable plants are monoecious plants, meaning they have both male and female organs on a single plant. Dioecious plants are more complicated to breed because the breeder must pollinate a female plant with pollen from a male plant. Seeds generated from cross-pollination of two plants will produce more genetic variation than seeds created through a self-pollination (monoecious plants) technique and, therefore, requires more time and effort to find and stabilize a sought after trait. Before purchasing seeds or beginning a home breeding program, it is a good idea to have a basic understanding of cannabis breeding techniques and terminology.

Landrace Varieties

Chances are good, if you’ve researched cannabis breeding, you have come across the term “landrace”. A landrace variety is a type of cannabis that has established itself in a particular region and has grown there wild for a very long time. Essentially, landrace cannabis strains are strains that are native to a particular area, where they developed naturally and have grown wild for millennia. Because of their natural stabilization through natural selection, landrace strains are stable, robust genetics that produce homogeneous offspring. In other words, landrace strains from a particular area will display very similar growth patterns, appearance, and cannabinoid/terpene profiles.

There are many landrace strains from around the planet. Landrace varieties are the foundation for most cannabis breeding programs, as breeders can expect little variation between landrace species of the same variety. Because landrace strains (of the same variety) exhibit similar growth patterns, appearance, and cannabinoid/terpene profiles, they make a solid starting point or building block for breeders.

In-bred Line (IBL)

In-bred line, or IBL, refers to cannabis strains made from crossing two almost identical genotypes. Breeders use this technique to acquire desirable traits and stabilize the genetic line. There is usually a lot of work behind each IBL strain as a large population of pure specimens has to be used to select the correct parents for breeding. Breeders who make IBLs also must face the issue of inbreeding depression, a result of crossing plants with very similar genetics. In many cases, inbreeding produces less than desirable traits and breeders must sort through hundreds, if not thousands, of offspring to find the particular stabilized traits they desire. The end goal of IBL is usually to create a highly stable variety for seed production.

F1 Hybrids

An F1 hybrid is created when a breeder crosses two unique genotypes (from either two landrace strains or two IBLs) and creates a first generation hybrid; for example, crossing two completely different landrace strains from different geographical locations. This might be done to create a hybrid that exhibits a sought after trait from each of the different parent plants. If both parent plants are very stable, the result is generally a very uniform offspring. One of the main reasons F1 hybrids are sought after is that they will show the so-called “hybrid vigor”. Hybrid vigor refers to how F1 hybrids will often have special attributes, such as enhanced yields, a shorter time to harvest, and/or a heightened resistance to drought or diseases.


Many of the seeds sold in cannabis shops or the seeds created by hobby growers are considered poly-hybrids. Poly-hybrids are crosses between two different hybrid strains. In most cases, the offspring of poly-hybrids are quite unstable. In other words, the offspring of a poly-hybrid will not necessarily produce the specific traits of either parent, but, instead, may exhibit a wide variety of traits derived from its entire lineage. This is why a home grower should not expect his or her poly-hybrid to be as homogeneous as a true F1 hybrid. However, sometimes a grower gets lucky and produces a poly-hybrid that is stable and exhibits unique attributes.

F2, F3, F4, F5…

When a horticulturist crosses two F1 individuals (landrace, hybrids, or poly-hybrids) a second generation, or F2, is created. As more generations are bred, they are referred to as F3, F4, F5, and so on. An F2 generation often produces a more diverse offspring, where more varying traits of the parent plants are exhibited, than an F1. With an F2, growers should expect 25% of the offspring to resemble parent A, 25% to resemble parent B, and 50% to be a mixture of traits from both parents. Breeders looking to stabilize a particular trait will continue to create subsequent generations (F3, F4, F5, etc.) until a generation is developed that produces uniform offspring with the desired traits. Again, this is why some aspects of breeding are best left to professional growers with facilities large enough to house all the plants necessary to stabilize the sought after traits.

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Backcrosses or BX

Backcrossing, or BX, is a breeding technique generally used to correct a particular trait. Backcrossing is done by crossing one of the offspring (F1, F2…) with one of the original parents (the parent with the desirable trait). Breeders will also cross the backcrossed offspring with the parent again to further stabilize that parent’s desired trait. Backcrossing is also used to replicate a clone in seed form. For example, let’s say a grower has a female clone and wants to create seeds that produce offspring similar to that clone. This can be done by choosing a male plant to cross with the clone and then backcross the offspring (with the original clone) as many times as needed until the offspring exhibit traits similar to the original clone.

Selfing (S1) Feminized Cannabis Seeds

Feminized seeds are popular among hobby cannabis cultivators. Feminized seeds will produce female plants instead of both female and male plants. In breeding, S1 refers to the first generation produced as a result of crossing a female plant with herself. This can be achieved by utilizing techniques that reverse the sex of the desired female plant to get it to produce male pollen. The male pollen produced by the female plant is then used to pollinate that female plant and the resulting offspring are S1 feminized seeds. Techniques used to get a female plant to produce male pollen include the use of particular chemicals (such as colloidal silver) or rodelization. Rodelization takes advantage of the fact that a female plant will, toward the end of her life, try to pollinate herself as a last ditch effort to produce offspring. By stressing a female plant during her flowering cycle, breeders can manipulate the female plant to create a few pollen sacs. The pollen produced by the female can then be used to self-pollinate that female and create S1 feminized seeds. When S1 plants are backcrossed with the original female plant, they can create S2, S3, S4 generations and so on. This is often done by breeders to preserve a particular strain’s genetic traits.

Although cannabis breeding can be extremely complicated and time consuming, hobbyists shouldn’t shy away from experimenting with breeding. The poly-hybrid strains a hobbyist is most likely already growing may not produce the most stable offspring, but it could still be bred to create something unique. In theory, if a home grower does get lucky and creates a strain with unique attributes, he or she could use a backcrossing technique to produce seeds that would make plants like his or her masterpiece.

When shopping for cannabis seeds, a basic understanding of cannabis breeding terminology will not only help a grower make sense of what they are purchasing, but also what to expect from that particular genetic. Professional breeders who have the area and time to produce truly stabilized offspring are the best bet for purchasing unique, but stable, strains. Professional breeders also continue to create and develop cannabis strains for very specific purposes (such as high CBD strains for particular medical ailments). There is no doubt, as cannabis laws continue to change in favor of legalization, that more reputable breeders will be established and even more new, unique cannabis strains will be developed. This is not only great news for cannabis enthusiasts, but also for the medical community where sophisticated cannabis breeding programs could be the key to unlocking new, powerful treatments and cures.

Eric Hopper resides in Michigan’s beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability.

What are F1 Seeds? What about F2, F3, etc?

Breeders often devote their entire careers to creating that one perfect cross. They achieve this by enhancing the strongest properties through selection and crossbreeding. These crosses are indicated by generation.

Let’s discuss what F1, F2, F3, etc selections are.

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  • What are hybrid cannabis strains?
  • What are f1, f2, f3, etc. selections?
  • Creating new cannabis strains
  • Pure breeding line or strain
  • Creating a stable f1 strain
  • Let’s recap.

What are hybrid cannabis strains?

The demand for new cannabis species is increasing with the natural consequence that there is plenty of experimentation by breeders.

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As a result of this (cross) breeding and experimenting, most of the species on the current commercial market are hybrids. These are plants that are a result of crossbreeding several cannabis varieties to amplify certain effects or characteristics.

As this crossing process evolves, the plants will eventually form seeds from different cannabis strains or generations.

Cannabis, like any other plant, exists as a pure variety or as a hybrid mix of strains.

Hybrids are the result of attempts to shape plants with specific characteristics, which are common in ruderalis, Sativa, and Indica strains. Successful crosses inherit the best traits of both parents.

When the industry started to commercialize, both pure varieties and existing hybrids were constantly mixed and recombined. These efforts have produced some of the best-known species today.

What are F1, F2, F3, etc. selections?

As you further specialize in cannabis cultivation, you will undoubtedly encounter more and more impressive terminology.

When I first saw the term “F1 strain”, I seriously wondered what car racing and cannabis have to do with each other (and if it was wise to combine the two).

Needless to say, the guys got a good laugh out of that one. It turns out it has nothing to do with the automotive sports industry, nor should we fear for Hamilton’s safety.

In this case, F1 means something totally different and very fascinating!

In a nutshell, an F1 variety is the first hybrid plant from a specific pair of parents and a new phenotype that is
independent, yet still closely related to the two parents.

But that just sounds confusing and doesn’t cover the load. Let’s go further back first before we take a leap into the unknown.

Creating new cannabis strains

The basics of growing plants are always the same. This also applies to cannabis. Male pollen pollinates the female plant. Nature has ensured this happens naturally.

But when creating a hybrid, the growers use selective breeding in a controlled environment. This entails that the breeder personally selects the female plant and the male pollen in order to get one or more specific characteristics in the offspring.

A few of the properties that can be improved through selection are rooting, growth potential, flowering period, color, bud structure, and yield.

The seeds germinated after this process are the first generation of hybrids from male and female parents. The plants with the desired characteristics undergo this selective process again.

Once the desired traits are achieved, the breeder stabilizes the species.

The next step is crossing the young hybrid with the parent species to enhance the characteristics.

This process requires a lot of patience and perseverance from the breeder since stabilizing the properties of a species usually requires three or more generations.

We distinguish the following generations:

To make a well-informed decision when deciding on what the ideal seeds for you, it is helpful to understand the differences between these different generations.

Pure-breeding line or strain

A group of identical individual plants that always produce offspring of the same phenotype when intercrossed.

Pure-breeds are unadulterated traditional landraces that have only interbred with similar strains and so have almost identical genes.

F1 – The first grow

F1 stands for “first-generation hybrid”. The F derives from Filius, which is the Latin word for “son”. Yes, botanists sure love their Latin 😉

You create an F1 strain by crossing two pure strains with completely different phenotypes. To achieve this, the grower will, for example, take 100 of their best plants and select only the very best mother plants based on a specific trait from one strain.

He will do the same with another (pure) species.

Let’s take a large plant (represented by two dominant genes, AA)
and cross it with a small but bushy plant (represented by the two
small recessive genes, aa). Since the resulting plants each receive
one gene from each parent, this will result in offspring with the following genetic makeup: Aa. All four offspring have the same makeup and will each be tall bushy plants.

The difference from the parent generation, in this case, is that these will not be pure strains due to the presence of the recessive gene.

F2 – Keep on crossing

To create an F2 strain, the breeder will cross two members of the F1 family together.

The offspring that comes from this crossing has
the genetic makeup of AA, Aa, AA, and aa.

That means that the F2 seed variety will have three tall plants and one short plant. So, the main difference between the F1 and F2 varieties is the amount of genetic variation and purity of the seed strain.

F3 – Reducing variation

As the cycle continues, we keep combining plants with the desired traits. We call this generation: F3. For example, if the grower was looking for short plants, he would select parents with the composition of Aa and aa.

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The result of this combination is two tall plants, each with the genetic markers of Aa, and two short plants (both aa). This breeding has actually reduced the variation towards a more stable variety. We call this process stabilizing.

Since F3 varieties usually start of rather unable we advise to cross it back with the selected F2 mother plant.

F4 – Narrowing the number of phenotypes

Once you’ve achieved a level of stability in your F3 variety, it is time to take your game to the next level. By continuing the selection process and using only the most stable plants from the previous generation, we’ve now reached the F4 variety.

F4 varieties contain even fewer phenotypes, which means that the plants should be nearly identical, with only slight variations in, for example, scent or yield.

F5 – Perfecting the process

By continuing on this path of crossing the strongest plants back within their own generation, the stability grows and a strong new species has emerged.

IBL Strains

After F5, the plants are IBL.

IBL stands for “inbred line”, AKA the holy grail of cannabis cultivation.

An IBL is a breed that produces offspring with stable and consistent genetics usually from a single dominant phenotype of the strain.

These strains will produce balanced and homogenous offspring with the desired specific characteristics time and time again for many generations.

Creating a stable F1 strain

When you pollinate a feminized female plant with pollen of the male-cannabis plant, you will get seeds, but not automatically a stable strain.

Breeders create stabilized hybrids and then continually interbreed, stabilizing their characteristics from generation to generation.

There are very few strains of stabilized hybrids as the process takes a number of generations, over several years, to achieve.

It is important to note that ‘stable’ is not the same as ‘true-breeding’. A true-breeding strain will produce consistent offspring of one dominant phenotype. In marijuana strains, you can mainly find this in landraces.

If you want to create a stable strain that shows the generation of the same characteristic after generation, you will have to stabilize it by crossing it back various times. By always selecting and crossing plants with the desired characteristics, you stabilize a species.

Since this is a time-consuming technical process that demands a lot from the breeder, it’s now clear where the -sometimes- massive price difference for different types of seeds comes from.

Let’s recap.

F1 is the result of crossing 2 separate varieties. The resulting seeds are F1 and they will be stable, meaning the plant qualities should be pretty consistent.

All the plants from these seeds will be very similar. This is great if you prefer a crop of identical plants.

F2 is a cross of 2 of your F1 plants from the seeds you bred. F2 is what true breeders are looking for.

The F2 seeds are unstable meaning the plants grown can show very different qualities, some may be good while others are bad. The F2 seeds can contain all the possibilities of phenotypes from all of the previous lineages of both parents.

F2’s are where you will find the next great strains which is what true breeders are consistently trying to do along with producing stable seeds for its consumers.

Once you find that special F2 plant, you need to cross it with another F2 from the same seed batch. Next, cross this plant back with your special F2. The seeds from this, called F3 will be unstable and may not produce your special F2 consistently.

To stabilize your new strain (The special F2 plant you selected) you now grow F3 seeds and pick one of these to back cross with your F2 mother.

The resulting seeds from this will be an F4 and more stable than F3 seeds. You continue this process to about an F5. By this time the F5 seeds should be stable and look like the new breed F2 that you found. You have now created your very own new strain!

So the main difference between F1, F2, and F3, etc. is simply the generation and level of stability that comes with them.

With each successive selection, the grower selectively takes the plants that are the best representation of the properties he desires and uses them for crossings.

I hope this has given you some insight and clarity and brought you are one step closer to being a full-fledged Marijuana high school graduate. Happy growing


Educated by one of the best breeders in the Netherlands, I chose to combine my passion for writing with the fascinating world of cannabis cultivation. What are the best strains for which occasion, what are the effects, and how to use responsibly? Let me take you on a journey.