cannabis breeding 101

Breeding And Preserving Cannabis Genetics At Home

If you’re interested in breeding your own cannabis strain but find scientific jargon confusing, and graphs and punnet squares put you to sleep, this is the blog for you. We break down all you need to know about breeding marijuana at home and how to preserve those precious fire clone-only genetics. Practical advice without the academic speak.



Breeding cannabis and continuing a lineage in seed is not the exclusive preserve of the experts. Home growers that have acquired high-level cultivation skills and mastered the essential techniques can easily transition from grower to breeder. Creating F1 seeds and hybrids is very doable. Most of the cannabis strains that have become legends were created by home growers. On occasion even by accident.

While it might not be possible to build your own seed bank from the grow tent in the spare bedroom. Small-scale breeding is a viable option. You don’t need a masters degree in botany. Just good old-fashioned dope growing experience will suffice.

Time in the grow op will have already given you a keen eye for pheno hunting. Plus you have developed the hands on cannabis tradecraft skill set to succeed.



Taking cuttings from cannabis plants is a great way to preserve a strain. Sometimes prized varieties are available in clone-only form, and the grower has little option other than continuing to take cuttings in order to preserve the genetics.

Cloning is a transferable skill and even more essential to cannabis breeders than growers. You need to have a consistently high success rate with cloning as a prerequisite to breeding.


F1 seeds can be produced with just a female marijuana clone. These seeds carry only the genetics of the mother. In order to accomplish this, the grower must reverse the sex of the female to induce self-pollination.

Most home breeders will purposefully stress the flowering female to produce a few seeds. Selfing is commonly applied to clone-only marijuana varieties to convert it to F1 seed form.



Ok, so if you are happy with a batch of regular cannabis seeds. Perhaps you want to make use of the males? Well, you can cross cannabis from the same batch. Assuming you are familiar with the strain and cropping from the same pack of seeds you can potentially select a breeding pair to cross.

This is an old school ganja farmer’s method mostly applied outdoors. Although, breeding from the same batch has potential indoors provided the original organic seeds are genuine. If so, not only will the resulting progeny be more or less stable but you will have saved cash on seeds for the next crop.

Before further breeding experiments, it’s no harm to practice collecting pollen and making seeds first. Breeding from a reliable batch is a good introduction to cannabis breeding.


A polyhybrid is simply a strain that results from crossbreeding two hybrid strains. When different landrace or inbred strains are crossed, this results in an F1 hybrid, a term used to label the first generation derived from the cross. F1 hybrids become F2, F3, and so on, as new generations are created via inbreeding.

However, if an F1 hybrid cultivar is bred with an F1 hybrid cultivar from a different genetic line, a polyhybrid is formed. F1 hybrids already possess varying genetic traits from both parent strains, meaning polyhybrids are even more diverse and unpredictable in the traits they possess. Creating polyhybrids is a great breeding method as it allows you to combine unique traits from a wide spectrum of cultivars. Although, as you can imagine, these strains are quite unstable and heterozygous. It takes some solid work to stabilise these varieties and ensure that their offspring are more uniform.


Breeding cannabis requires quite a lot of space. You need a nursery and propagation area and different rooms for male and female specimens to avoid unwanted cross-pollination. Even more space is needed if you intend to start breeding polyhybrids over multiple generations starting with four inbred cultivars. If you intend to begin this process, you’ll need to learn how to pollinate your flowers in the correct way.

Seeing as you’re considering breeding, you are probably already well aware of this fact, but it’s always worth reiterating: Keep your males away from your females! This is especially important when looking to breed a polyhybrid because of the increased chances of breeding the wrong varieties together.

First off, you’ll need to collect pollen from male plants when the time is right. Pollen is ultimately plant sperm, and is needed to fertilise female flowers to make them produce seeds. When the male pollen sacs have opened, place a sealable bag over the plant and give it a shake.

Female plants are ready for breeding during the early flowering phase when small, white pistils start forming. These “pre-bud” structures are basically little hairs that protrude from the calyx to catch pollen. Next, isolate the chosen female plant to further prevent any unwanted fertilisation. Consider setting up a specific fertilisation area to avoid any mishaps.

To pollinate female plants, place the pollen bag over branches that show bud formation. Seal the bag over individual branches and shake again. Leave it there for around 1 hour and repeat the process with each branch that bears buds.

It’s vital to document everything you do when breeding cannabis, especially during the more complex process of creating polyhybrid strains. It’s easy to mix up genetics and lose track of which male you bred with which female, and what strain each of them is. It’s best to label every plant individually so they can be easily identified. It’s also a good idea to create a spreadsheet or draw out a flowchart on a whiteboard to keep track of every cross you’ve made with each individual plant. Add dates beside every documented task to help you estimate waiting periods accurately.


Genuine F1 Hybrids are the jewels in the crown of the Royal Queen Seeds catalogue. The cold truth is creating fantastically potent, productive and vigorous growing F1 hybrids is a long term process. Professional breeders invest years of their lives into breeding projects and select cultivars from hundreds if not thousands of cannabis plants.

Genuine F1 hybrids can only be derived from crossing pedigree stabilised or landrace strains. They express genuine hybrid vigour. Unless you’re planning a strain hunting expedition, tracking down heirloom landrace seeds is hard graft. It’s probably more convenient to stick with the RQS catalogue for awesome hybrids.

Similarly, filial breeding can be complicated. Honestly, it’s far too demanding for the first time home breeder. By crossing a pair of F1s (first generation) the resulting progeny is the F2 (second generation). Unfortunately, these seeds will be far less stable and far more difficult to work with than the previous F1 generation.

Careful selective breeding in large numbers is required to succeed with this approach. Often it takes multiple generations of breeding perhaps until F5 (fifth generation) or even F6 (sixth generation) before the line can be stabilised.


Have you ever purchased the same cannabis strain multiple times and noticed that it looked completely different each time? Maybe it even tasted slightly more sweet or sour than before. Or maybe you’ve grown the same strain repeatedly and realised how different one plant looked from the next? These differences within the same strain are referred to as genetic variability. Even though plants share the same lineage, their unique genetic expression, or phenotype, is a result of how their genetics respond to the environment.

Differences in phenotypes can manifest as variability in size, resin production, colour, and so on. Strains can also vary in their chemotype. This refers to the chemical constituents that they manufacture. One plant might have higher levels of a specific terpene, whereas another may have slightly higher levels of CBD. If you germinated a bag of seeds that all shared the same lineage and noticed a large difference between the phenotype of each plant, this would mean that the strain is unstable, and that the seeds are heterozygous. Although this isn’t necessarily an issue for hobby growers, it can become problematic for commercial growers looking for strict consistency among their crop.

This consistency is possible, and can be achieved by stabilising the genetics of a strain. This will then produce seeds that are more homozygous, featuring significantly less variability between phenotypes. But how can breeders go about stabilising a strain?

One way to achieve this is called backcrossing, also known as “BX” within the cannabis breeding lexicon. When breeders are aiming to create a new strain, they select two parent strains with desirable traits. Upon crossing them, the first generation is created. Backcrossing essentially refers to taking a member of this generation back up the family tree to breed it with one of its parent strains. This type of inbreeding helps solidify the presence of one of the parent’s genes as they are bred together repeatedly.

For example, if the female parent strain was particularly high in CBD and myrcene, thus producing a calming effect, by breeding her with one of her male offspring that also shares some of these traits, the plants of the next generation would be even stronger in those traits. This is because they will contain more of her genetic material than the original generation that was also influenced by the male parent.

Although backcrossing is a tried and tested way to stabilise cannabis genetics, excessive backcrossing can cause some issues. By inbreeding plants to such a degree, any recessive genes that produce undesirable traits will also be strengthened and passed down to all plants of subsequent generations.

As you can see, there are quite a few ways to preserve your favourite strains, and turn them into new strains of their own. This guide is meant to give you a good general overview to get you started, before delving into the more complicated aspects of it.

If you have an amazing strain you want to preserve you need to read this blog. Lets talk about breeding your own weed strain.

Cannabis breeding 101

Ever wonder how grower’s are able to tweak and create new strains of Cannabis? The goal is to concentrate the attributes of each strain you like to it’s maximum potential. Cannabis breeding consists of refining the genetic makeup of 2 plants or strains. Crossing these 2 different strains result in a new strain or hybrid. It’s important to know the genetic makeup of the seed you choose as this will directly affect the outcome you’re looking for. Cannabis breeders are breeding to strengthen and purify strains as well as enhance certain characteristics like yield, potency, aromas and taste as well as many other factors.

When growing cannabis, it’s important to ask the breeder for the history of the seeds and which strains were used. Should the breeder not have the information readily available, you really can’t be sure what you’re getting. With legalization, breeding is understandably increasing in popularity but can be very technical. With a little research, and likely some trial and error, you can even try it on your own.

Cannabis Breeding Basics

Cannabis plants can be either male or female. Consumers are most concerned with the female plants as they produce the floral, dank buds we’re looking for. The male plant however plays a crucial role in the breeding and pollination process which enables the females to produce those buds. A match made in heaven.

In order to cross- breed, you need a male plant from one strain to pollinate a female of another. Once this happens, the female will produce seeds that contain genes from both the male and female plants used. Seeds are then harvested and grown. This is how you create a hybrid.

So how to know if you should choose a male or female of each strain? The traits of the female tend to carry over to the seeds more often than the male. Grower’s typically know the traits of the males they’re working with and will choose a male to best compliment the traits of the female. If you’re knowledgeable about strains the possibilities are endless if you have an intentional breeding approach.

How to Guide to Breeding

Once you’ve selected your two parent strains, a male and multiple female plants are contained in a breeding chamber to enable pollination. These chambers can be as fancy or as simple as your budget allows. It consists of a simple enclosed space using plastic sheeting to control the environment during pollination. A male plant is capable of upwards of 20 plants at once, not with just a few seed pods, covered with seeds.

Best practice is to use one strain of male per pollinating attempt. If you like, you can also grow the plants vegetative for a few weeks, but it’s not required. At this stage you’ll need to put them on a flowering light cycle : 12 hours of light, 12 hours of dark.

During the first weeks the flowering stage, the male will grow pollen sacs. This pollen will be released from the sacs into the air, land on the females and pollinate them. It’s crucial to have an enclosed, controlled breeding chamber to one contain the pollen and to prevent outside pollen from getting in.

You can assist in the process of collecting the pollen from the pods and applying them directly to the female plant or by shaking pollen from the male directly onto the females. The females continue to grow and will produce both seeds and buds. These seeds will contain the genetics of both male and female.

Seeds are harvested and dried once they’ve become mature. The next step is to dry the seeds. This needs to take place in order for germination to happen. Typically flowers are harvested 3 to 4 weeks prior to the harvest of seeds.

You’ve now created seeds- a hybrid of 2 parent strains – which can be grown on their own.


In the same way that you and your siblings carry different physical attributes from each of your parents, this also translates to cross pollination as well from each parent strain. You have your moms nose and your dads eyes, but your sibling has your mom’s eyes and your dads nose. Each seed is also unique in its composition and carries different traits, and combinations of traits from each of the parent strains. Seeds expressing and carrying various traits are called phenotypes.

With cannabis, you usually want seeds that have the same set of genes, these are homozygous. Plants that produce phenotypes with a lot of variety are called heterozygous.

Homozygosity is what ensures the plant will be consistent in producing the same genetic makeup of seeds, promoting uniformity of stock and that buyers and consumers alike will continue to get the same seeds and plants time and time again.

Backcrossing debunked :

If you’re a connoisseur, and are geared towards quality. You’ll understand that high-quality breeding doesn’t end there. Once the breeder is satisfied with the cross-strain they’ve created, next steps are typically to backcross the new strain with the parent , essentially inbreeding the strain. This in turn will render the strain to be more homozygous, ensure the genes continue to pass down through generations and strengthen its genetic makeup for congruency.

It’s important to understand that becoming a breeder requires a lot of time, patience, and most of all, passion. It’s a process like any other. There will be trial and error, crossing and backcrossing before you achieve the end result you’re after. But once you do, you can still expect to do a good chunk of backcrosses to replicate it in seed form. “Nothing good comes easy” they say. Effort usually equivocates reward. Good luck!

Cannabis breeding consists of refining the genetic makeup of 2 plants or strains. Crossing these 2 results in a new strain or hybrid. Learn More.