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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.

Contents:

WHY DABBLE WITH CANNABIS BREEDING AND GENETICS?

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.

HOW TO PRESERVE PRECIOUS MARIJUANA GENETICS

CLONING

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.

SELFING

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.

SMALL SCALE BREEDING OPTIONS

BREEDING FROM THE SAME BATCH

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.

POLYHYBRIDS

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 POLYHYBRIDS AT HOME

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

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.

BACKCROSSING

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 Genetics 101: Stabilising a strain

Procedures to stabilise cannabis strains are poorly understood, even by breeders producing commercial strains. Stability refers to the variability and predictability found in the offspring of a parent generation: when a strain is unstable, variability will be high and predictability low; with a stable strain, the reverse is true.

Variability & predictability

Variability in this case refers to the range of different phenotypes that will express when hybridising two different strains; predictability refers to the expected distribution ratio of the different phenotypes. When crossing stable parents, Mendelian inheritance dictates that: 50% of the offspring will resemble both parents equally, 25% will express traits closer to the mother and 25% closer to the father.

Usually, breeders will stabilise a strain over several generations. First, a healthy mother and father are selected, and bred to produce hybrid offspring that will be of varying predictability depending on parent stability. Hence, if the mother and father are both considered stable, their offspring would be expected to express three phenotypes as outlined above.

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Stable vs. true-breeding

It is important to note that ‘stable’ does not equate to ‘true-breeding’. A true-breeding strain is one that will produce consistent offspring of one dominant phenotype (with few to no specimens unlike their siblings); in cannabis, these are usually found among the landraces and traditional cultivars. Further, breeders may use the term true-breeding to refer to single traits that will always recur (such as purpling or webbed leaves), rather than for overall phenotypic expression.

Stable parents usually produce predictable, homozygous offspring, although with a greater degree of variation than found in true-breeding strains. However, if one or more parents is unstable, crossing them together results in a range of heterozygous offspring that can express any number of unpredictable traits, and which will not correspond to predictable Mendelian ratios.

The traits that are dominant in each parent are recombined to provide the genetic basis for the next generation. The initial crossing of two unrelated parents is known as the filial-1 (f1) hybrid. Usually, the best examples of the f1 hybrids will be crossed to produce the f2 generation, which is usually even more unstable than the f1.

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Crossing & back-crossing

With several generations of crossing together brothers and sisters from the same parents—selecting on the basis of desirable traits—a greater degree of consistency and therefore predictability can be achieved. Desired traits become dominant and will always appear, while undesirable traits are gradually eliminated from the gene pool and are no longer expressed.

For some traits, back-crossing plants to previous generations allows traits to become stabilised more quickly. Many breeders erroneously believe that some degree of back-crossing is necessary to stabilise any strain, but in reality this technique is only required for certain characteristics.

Inbreeding depression

After crossing and possibly back-crossing for several generations, the desired traits should begin to express in all individuals. However, after many generations of essentially limiting and reducing the gene pool so that only desired traits express, the resulting paucity of genetic material can lead to a level of inbreeding that is detrimental to the overall health and sustainability of the strain.

Put simply, if two related parents both carry the same recessive allele, which happens to be defective or otherwise deleterious, the chances of two identical copies passing to the offspring are far higher than with unrelated parents. If two individuals carrying these faulty alleles then breed with each other, the undesirable trait will be dominant and breed true in all subsequent generations of the lineage.

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Outbreeding for improved diversity

For this reason, when strains begin to experience such severe inbreeding (known as inbreeding depression), it is common to introduce a new, unrelated father in a process known as outbreeding.

Inbreeding depression will occur more slowly if there is an abundance of genetic material from which to form new offspring. Therefore, with smaller population sizes, inbreeding depression can occur rapidly. This is especially common in countries with a strong cannabis-using culture that have not decriminalised the means of production, such as the Netherlands where small libraries are maintained due to risk of discovery.

Comments

41 thoughts on “Cannabis Genetics 101: Stabilising a strain”

Really fantastic information can be found on site.

I’m commenting to let you be aware of what a amazing experience my friend’s child experienced checking your blog. She learned such a lot of things, including what it is like to have an amazing helping nature to let other individuals very easily know precisely some hard to do topics. You truly exceeded people’s expectations. Many thanks for supplying these warm and friendly, trusted, informative as well as unique tips on that topic to Tanya.

Well sounds like true grit.im going with mother nature and jamaica

99% of everything written here is crap. Get your facts straight.

Well said! Kudos

Wouldn’t feminized seed production count as back-crossing? Of course it would. How many generations before inbreeding depression sets in? 3? 5? Some growers are headed toward a brick wall.

Thanks for sharing this knowledge. Just getting a grasp on breeding. Lots to consider, track and log and “TIME”
Cant help but hear @MotherNatures points about Sun Rain wind Organic outdoor altruism but science doesn’t stop.

thanks for a great article

as far as breeding goes,can feminized plants pollen if there sprayed with the silver collidal spray and collected and then used to pollinate another feminized plant create only female seeds?in theory ..

Imagine that the plants are people.
First, you have sex with a sibling. F1.
Then, your inbred offspring do the same. F2.
And then those even more inbred offspring do the same again. F3.
Imagine how genetically superior we could all be, completely severed from Nature.
How beautiful. How potent. Really ??
Stabilized hybrid horticulture is a good example of how myopic, greedy and sick humans have become.
And yes, stabilized hybrid cannabis culture started here at Sensi Seed Bank. Yes, you are the experts.
I have been growing organic, open pollinated cannabis outdoors for 40 years, growing with Nature, not against it.
My weed is sweeter, higher and genetically stronger than any inbred mutant will ever be.
When you take away the Sun, take away the earth and the wind and the rain and abuse the sexual integrity of the medicine, all you have left is a drug that makes you even more stupid than you already are.
Nature knows best, You can work with it, selective breeding is natural, progressive. Engineering a genetic cul-de-sac is not.

So true. Nature took care, is taking care, and will always take care. Humans only pollute.

you are a toxic person

you are too…..if you think your not, think again.

Well said! Kudos

Working outdoors with landraces, with nature, is my preference – predictability, surprise, variation, observation, selection all satisfy and reward. Explore the flow.

this article helped a lot towards my knowledge of breeding and creating a reliable strain with only the best genetics, I had a general idea but wasn’t sure. I’m going to be crossing some really bomb strains, like cup material

Talking of genetics becomes very complex. Although the mendelian square is a good ground to start, we are truly opening up a diverse selection of many different allele that are either closely related or situated upon differing loci upon the DNA strand. The combinations of these allele in pairing can either be expressed or switched off depending upon the allele itself. The back crossing becomes the stabilizing element, and even introducing a completely different strain can produce a hybrid of stronger growth and bigger yield. Creating a phenotype that breeds true having characteristics that are desired is a very lengthy process and careful thought along with detailed notes to review so as to deeper understand the process involved which is hidden in the genetic coding. Letting natural selection to take place without any human intervention then the phenotypes revert back to their original strains. I learn this from breeding show guppies.

I dont think ANY of you know what youre talking about. Great speculation though!!

send me your email bro, if you really do this and you’re good at it and you know about it we can help each other out. I breed the best strains and select only the best phenomes, mostly the afghan indica dominant phenomtypes of all my strains

Tony I have some landraces Afghani s there beautys,,also got an indica dominate strain thats insane Blueberry headband x Green Poison indica dominate..I m still learning the whole breeding thing but always looking to talk to good people..

Successive selfing and selection of desirable phenotypes that are as identical to the founding mother as possible works toward stabilizing a strain.

Each generation will carry less and less undesirable genetic characteristics as those that do show up are removed from the breeding project.

Once the strain is reduced to as near a true breeding line as one desires the project can be called complete.

If the breeder desires the near true breeding phenotype can be then back crossed to the original mother plant and the process completed again as many times as desired.

It should be noted that any out breeding or back cross to the original and desired phenotype will result in an increase in genetic diversity requiring additional breeder selection and removal of undesirable traits.

While this process involves much inbreeding, any negative results are likely to be easily identified and removed from future use. Once bad genetics are found and removed they are gone, this is ultimately a good thing.

hi Dear . i have question
if we have 2 Clones from 1 Single (superStrain)
and Trying to polinate one of them with using collodial silver for sexing with other one ? what is future results ? can this seeds apear Exactly as mother-father plants?
can seeds have genetics problems?

Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

With best wishes

I have been growing cannabis for 15 years, received
about 30 seeds from a breeder friend o mine, most crap
seeds or died, 1 damped off small runt to darn, but the
3 seedlings I did grow are as follows. Plant#1 I broke the tap
root unfortunately, but has been fed organic liquid karma
i think has built a new tap root now, she is the best cannabis
strain i have ever seen in 15 years now, but is secret will not tell,
But i did name the strain CLEOPATRA is a pure indica though,with long fuzzy white hairs, at only 7 inches tall and
STINKS, will post up some photos
on the forums sometime, I AM THE ONLY PERSON WITH THIS INDICA
STRAIN OR TYPE OF CANNABIS, WHICH I BELIEVE IS EXTINCT, MOST
LIKELY EVEN THE NATIVE COUNTRY IT IS FROM DUE TO WARS ETC. Plant #2 She is a BERRY cocktail odor.they have been growin in 50% perlite,
and a 50% vermiculite mix I make myself, for ex. drainage,
Plant number #3 is a burnt rubber ORANGE, and is a MALE PLANT
BUT REALLY STINKS, AND ALL 3 STRAINS ARE SO CHRONIC.
AND ARE F-2 OR F-3, OR HIGHER? THEY ARE MY OLDEST SEEDS
FROM 4-5 YEARS SAVED FROM MEDICAL COLLECTIVES, THE
CROSSED BREED BY MY FRIEND, I PLAN ON STABLIZING,
ALL 3 PLANTS, THEY HAVE MISSING PARTS ON SOME LEAVES.
I TRIM THESE WITH MY CLIPPERS, and they seedlings
start growing some what more normal for themselves.
I will take cuts of all 3 strains, Cleopatra is my favorite,
because of the plants odor which as i said is a secret,
and is the strain i have been searching for 15 years now,
i have never seen so much resin in a cannabis plant like
these 3 strains just really old clone INDICA STRAINS,
JUST UNBELIVABLE QUALITY, I HAVE CROSSED A PURE
SATIVA MALE. WHICH WAS VERY TALL BUT SPICE ODOR
AND THE FEMALE DONOR PLANT WAS A PINEAPPLE, MOSTLY
SATIVA. ALL HAND POLLANTED BY ME, ON 1 BRANCH,
1 1/2 2 WEEKS INTO 12/12 -JUST SPRINKLED MALE POLLEN
AND MARKED W/PLASTIC BAG, AND
GARDEN TIE, TURNED ON MY FAN AT PLANT, 3 WEEKS
LATER SEEDS WHERE DONE, AND FLOWERS DONE AND NO MALE PLANTS LATER
ALL FEMALE AND DONE IN 2001-0R 2002 BEFORE PEOPLE
IN HOLLAND LEARNED-HOW TO FEMINIZE THEIR SEEDS?
I DO HAND POLLANTE THEM THROUGH, GREENHOUSE
SEED CO. LET THE MALE POLLANATE IN THE SAME ROOM,

MY MALE PLANTS WHERE OUTDOORS AND MY FEMALE DONOR INDOORS, UNDER MY
400 HIGH PRESSURE SODIUM VAPOR BULB.

I couldn’t get through the first few sentences before realizing this dude is delusional. Lol.

I think it was one long run on sentence, i didnt see any periods.

I sure hope that,” secret strain ” didn’t cause the psychosis

lol i started laughing when he SEAMLESSLY TRANSFERRED TO CAPS AND KEPT ON RANTIN’

Reading that tells me why my Cali connection GSC seeds are all so different. 6 seeds. 1 never cracked. 1 damped off (my fault), the other 4 are all totally different. CCs GSC seeds are crap! Beware!

I had a similar experience with Cali connection green crack. Phenos were all over the place. Most breeders don’t bother stabilizing their work and expect you to do the pheno hunting and cloning. I have only really had good luck with OG18 reserva privada. I’ve grown dozens of strains from seed and practically all of them have had multiple phenos.

It is so funny you guys actually arguing about stability, assuming the heredity mechanism is Mendelian.

99% of the desired traits are quantitative, breeding and stabilizing is relevant in terms of populations, GWA, and is usually acquired by mass selection.

I am a grower out of oregon.Been growing for 20 years. Study cannabis botany for 5 years or more.I understood ur breeding medellain scale and it was thefirst time i saw that scale.u guys explained things well! Thank you!

Also this for ‘Why’. F2 is highly unpredictable n varied because it shows phenos of parents, grandparents plus great grandparents. F3-F5 wil also show recessive genes, once 7th generation is reached it should be fairly true-breeding providing good practice and selection is involved. If trying to create an IBL note taking and photos are a huge help.

Hey there, awesome read for those starting on a breeding project. Myself; i already understand most of that as am in the feild of horticulture, already have the basics of crossing and inbreeding and have successfuly done both producing both an F1 and linebreeding from stable IBL. Would like to see bit more on the outcrossing (namely using hybrids or ‘double-crossing’) and also on top crossing or ‘3-ways’.

How is an f2 that you choose a selected mother that will pass on desired traits become more unstable…..I’m sorry you choose a male that has similar traits then you would have a much more stable strain. “F2″&”F3” …..etc. Along with natural selection is how mother nature stabilizes strains…..wake up ppl and just observe nature

F2 and even subsequent offspring can easily be more unstable because that’s when recessive genes will appear. The first offspring of an unrelated pairing are F1 and if only one side carries a recessive gene it will carry on to a small percentage of the F2 generation. If both original patents carry a recessive gene it will show in a F2 generation but if only oneof the originals carries the recessive gene it won’t show in the F2 generation. So you’d have what you think to be a more stable strain until F3 and subsequent generations with low percentage of plants with wild genetic variants. It’s also a good way to find “hidden” recessive traits that you may desire in your strain but there is a give and take in every breeding between becoming more stable and inbreeding more recessive unwanted traits.

Stabilising a strain: Procedures to stabilise cannabis strains are poorly understood, even by breeders producing commercial strains. Read more.