cannabis breeding techniques

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.

SMART Breeding: Growing the Next Elite Strain

Legalization and new techniques in cannabinoid science usher in a new age of marijuana. Photo by Gracie Malley

Being a buyer at Harborside Health Center, a bustling medical cannabis dispensary in Oakland California, offers me the unique and unprecedented opportunity to view a diverse spectrum of cannabis of all varieties grown with countless different indoor and sungrown methodologies. But with more choices available than ever before, growing a strain that appeals to a wide range of cannabis consumers occurs only with the melding of art and science.

In an era where it has become easier both legally and technologically for gardeners to cultivate cannabis, the amount of product available in markets like ours is immense but repetitious. Photo by Gracie Malley

Having access to excellent genetics is as easy as strolling into the local dispensary to choose a strain either from racks overflowing with verdant clones or seed catalogs that are large as the ones in the Netherlands. Although their choices are myriad, growers gravitate toward the most well-known or popular strains and mostly ignore the rest. The result is that both large commercial cultivators striving for dependable and bulletproof plants and newbie growers who only grew a few clones are likely to have similar strains.

Access to desirable genetics for both high-level cultivators and novice growers has become more and more equal. For example, the variety Gorilla Glue #4 went from being exclusive and highly desired to market saturation in a period of less than two years. Compare that to the previous crazes like Girl Scout Cookies, which took several years to reach a wide availability for the Chem/OG/Sour family, which remained tightly controlled for a decade becoming widely cultivated. The days of $1,000 OG Kush clones are not yet a distant memory. It is fairly easy to correlate this access with both the legal tolerance of dispensaries as well as the cannabis community’s vigorous networking on online forums, and we can only expect the rate of cycling from “rare” to “available” to increase rather than decrease.

Cultivators frequently ask me what they should grow to guarantee a niche on our shelves, and my answer frequently disappoints: “Something we don’t see all the time.” It should be no surprise that growing from seed is the best way to do this, allowing the grower to pick a phenotype that is both unique and all their own, at least until the grower gives someone else the cutting. Wide retail access to reliable clones in legal states has done much to dampen cultivators’ interest in sprouting seeds — let alone saving a male to make their own hybrids — and that has much to do with this slump of diversity in the current marketplace as well.

It would not be surprising to see future combinations of modern pre-potent varieties and older, unexplored landraces as breeders search for the promise of new offerings. Photo by Gracie Malley.

The monotonies are easing up a bit. At Harborside the Chems, Cookies and purple Indicas remain the best sellers but hybrids of older African landrace varieties such as Red Congolese and Nigerian Silk have gained popularity and have both modern THC potency levels as well as unique terpene sets. The return to older gene pools is where the search for newness often takes us.

The most interesting development: the hyper evolution of cannabis concentrates. This brought about a “second coming” of hashish culture albeit in a new and modern form. Cannabis concentrates are more popular than ever, and the diversity of type continues to multiply. The potency and purity of these concentrates is greater than previously available because extractors have better access to both high-quality input product and cutting-edge technology.

The future promises many surprises for cannabis users. Photo by Nadim Sabella Photography.

A new development phenomena is seed breeders and concentrate makers working symbiotically. The resin covered shattered bracts left over from seed collection are perfect for extractions and collected when green. Some seed producers have created brands for their own extracts to take advantage of their labor. What is most interesting about seed breeders extracting is the potential influence of extract making on breeding. Middle Eastern farmers once bred for traits such as gland size or for the gland to break off from its stalk, this is essential for plants intended for hashish production. Modern breeders growing specifically for concentrate production have the same thoughts, as whole crops of cannabis plants are extracted. These breeders may also tinker with traits such as toughness of the resin gland’s cuticle or thickness of its wall. This would be a major advantage to extract makers.

Photo by Nadim Sabella Photography

Terpenes are another component of the resin that is being actively explored and bred for. Ed Rosenthal’s seminal article in Big Book of Buds vol. 3 published in 1998 followed by Dr. Ethan Russo’s 2011 paper on “the entourage effect” cast the cannabis plant’s naturally occurring aromatic compounds in a new light. Rosenthal, then Russo, effectively outlined the interaction and synergy of terpenes with THC and cannabinoids, which basically illustrates that each strain’s unique “high” is mostly based on how those aromatic compounds alter THC’s effect on us.

High Pressure Liquid Chromatography testing for terpenes is utilized throughout the cannabis industry and is accessible to almost any cultivator in legal states. Buyers may finally be moving away from overall THC potency being a dominant market force with this new awareness and interest in terpenes. The typical cannabis flower tends to have about 1% terpene content, although there have been reports of some with 3%+. These levels will be increased by breeders.

With legal cultivation it will become easier for farmers to utilize classical breeding methods. For the best results a very large number of plants are cultivated from seed only a few are chosen, this process was very difficult to follow during prohibition. Even in the modern era many cannabis seed breeders still work in batches of selections of far fewer than 100. It’s easy to imagine the potential if that number increased to a thousand or more!

The other perhaps more potent element at play is the cannabis genome. Researchers already have a good working knowledge of the genomes various triggers for growth structure, phytochemical output (i.e. cannabinoids and terpenes) and many other traits. The threat of GMO cannabis seems to spook many from supporting these genome studies but in truth what we stand to gain is worth setting those fears aside. One of the more exciting prospects is the use of the principles of SMART (Selection with Markers Advanced Reproductive Technologies) breeding — using the knowledge of the genome to achieve the full potential of the plant, but breeding with traditional methods. It offers us our best hope in dealing with one of the most challenging issues that we face as the scale of cannabis cultivation grows larger; mold and insects or more specifically the pesticides used to fight them. By following the plant’s genomic map and breeding towards increased resistance, we would be able to step closer to fighting infections with out the use of chemicals.

Pest resistance is not the only benefit that SMART breeding offers, future strains will be intricately and immaculately crafted works of scientific art. Imagine the ability to choose preferred cannabinoid content, terpene set and growth style like a chef in a kitchen with any ingredient at your disposal. By utilizing landrace, older strains, and feral strains the SMART breeder will be able to adeptly reach into nature’s toolbox for the right genes.

I hope that the cultivator who is wondering what he/she should grow next can sense the pulsing current that carries cannabis persistently onward: newness. Finding it yourself is as easy as this: grow seeds and pick your favorites, retain males, check them for potency, yield, etc. and collect their pollen to make your own hybrids.

Finally, use quality lab testing to identify your most unique plants. The recipe for the next “elite strain” in your local marketplace — if not the entire world — is truly that easy.

Legalization and new techniques in cannabinoid science usher in a new age of elite marijuana strains.