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About Cannabis Breeding

Seed-and-Smith-Flower- perfect cannabis flower

Cannabis has been around for thousands of years, documented back in prehistoric societies from Asia, Europe, and Africa. Hemp, a derivative of the cannabis plant, had many uses in the past including making rope, bags, clothing, and other mundane goods. Of course, back then, there were no insane THC percentages or scientific analysis during cultivation. The cannabis we have today is the result of careful breeding, and the progress we’ve made in understanding genetics. So how did we get here?

Cannabis Genetics

We first began to really understand the genetics and inheritance from the work of Gregor Mendel.[1] Mendel set out to explore out the principles of hereditary to find out why a specific set of traits would be passed down to a child, while others would not. He chose pisum sativum, or the common pea plant, to run his experiments on in the mid-1860s. Mendel ran a ton of experiments, ranging from crossing two pure-bred pea plants to breeding hybrids, offspring, and every combination in between. Before his work, many people assumed that breeding would produce offspring that exhibited a mixture of traits from the parents. However, Mendel’s study was instrumental in showing that genetics were much more intricate than this, leading to the discovery of dominant traits and recessive traits.[2]

The research Mendel did would shape the scientific and medical research greatly in the years that followed, including that of cross breeding in agriculture to create something new with specific traits. The cannabis industry was no exception.

Cannabis Breeding

Before the advent of purposeful breeding with the cannabis plant, there was already a huge variety in the genetic makeup between different cannabis strains. This was a result of environmental pressures and natural selection. As you can imagine, a strain of cannabis grown outdoors in the high mountain ranges of Asia might be hugely different from one grown close to sea level in California, with different characteristics including trichome volume, shape of the plant’s leaves, and the height of the plant to name a few. However, these were natural differences and could not be attributed to purposeful breeding. These are known as landrace strains.

As Mendel showed, breeding cannabis within the same family will produce the same type of plant; if you breed two sativa strains together, the resulting strain will also be a sativa. Now, this sativa may be a little different, especially if the parent strains have different lineages and genetics. If you want to learn a little bit more about the physiology and differences between the types of cannabis plants, you can start with understanding the differences between indica and sativa. Breeding has provided the cannabis industry with awesome strains such as Super Lemon Haze, Girl Scout Cookies, White Widow, and countless others.

The Cannabis Breeding Process

Traditionally, when breeding for a specific purpose, you need a male and a female, and this is no different with the cannabis plant. While both parents are necessary in cannabis breeding in order to create a successful hybrid, the female cannabis plant is the one who produces the actual buds of cannabis that we all know and love. 

Cannabis breeding is usually done with a purpose, whether it is to yield high THC percentages, cultivate CBD potent flower, create certain terpene profiles, or for specific psychoactive effects. This is done by pollinating a female cannabis plant with a male one. Within a few weeks of the flowering stage, the male cannabis plant will grow pollen sacs, which allows the pollen to gradually spread to the female plants. This is done in a closed environment where the pollen can contain itself from external factors in order to maximize the amount of pollen that reaches the female plants. In a suboptimal closed environment, pollen can also be applied directly to the female plants. Once this is completed, the female plants will start producing seeds in addition to the cannabis flower.

Hybrid Seeds

The seeds produced are hybrid seeds! Once you plant them and they flower, they will exhibit characteristics of both parent strains; however, the job isn’t done yet. These offspring are what are known as genotypes.[3] Just as siblings are similar but not identical in the vast majority of cases, no two plants are the exact same. This is why many times you may see a range of THC percentages on a particular strain or notice slightly different flower sizes when repeatedly buying a favorite strain. Many of the hybrids you see for purchase have been bred over and over and over again using the desired genotypes; this lowers the variation found in offspring and allows you to narrow down the specific characteristics you like about the hybrid so that they show up in offspring reliably.

In addition to genotypes, there are also phenotypes of each cannabis strain. These are the different variations in cannabis plants that result from the growing process and environment. Essentially, the phenotype is the physical representation of the genetic makeup of the strain (genotype). This can be seen by the equation below:

genotype + environment + the interaction of genotype and environment = phenotype

So, even if you use the same exact seeds as another breeder to grow cannabis, the resulting plant will have some variation due to the type of environment (indoor vs. outdoor) and the methods of the individual grow teams such as soil composition, nutrients, watering, and many other factors. Phenotypes may manifest themselves in color, shape, flower yield, and many more different ways.

Cloning a Cannabis Plant and Strain Stability

With all the talk regarding genetic diversity and phenotypic differences, how do you get the same exact genetic makeup once you’ve found a winner? The answer is cloning, or asexual reproduction. Cloning a cannabis plant involves taking a cutting, or tissue culture, from the female plant you wish to clone with scissors or a razor, then growing it as its own plant. This ensures the genetics of the new plant are the exact same as the mother. However, this is a delicate process, and any imperfections can lead to genetic mutations, so must be done carefully. 

Chemovars and Cultivars

At Seed & Smith marijuana dispensary we like to use the labels chemovars and cultivars. Chemovars are the different phenotypes of a single cannabis plant, as discussed above. These are the candidates for a rigorous testing process where we may test tens to hundreds of different chemovars to find the one that produces everything we are looking for. This winner must be appealing to the consumer, have vigorous growth traits, display pest resistant characteristics, and yield a high amount of flower. These chemovars undergo strict anecdotal and laboratory testing before entering the cultivar phase. This stage is sometimes known as a pheno-hunt.

Once a particular cannabis plant has been chosen, they are rotated into our cultivation program as a cultivar. This plant will be grown for a maximum amount of foliage as opposed to flowers. This extra plant tissue allows us to scale our cloning process. These tissue cultures are dipped in a rooting hormone, placed into a water rich medium, and eventually housed in an extremely humid microclimate. This creates a carbon copy from the chemovar we chose in the initial pheno-hunt, which is ready for commercial scale production.

This cannabis breeding technique assists in strain stability, where the variance between individual crops becomes less and less until we can reliably reproduce flowers and buds that are consistent every time. This method of plant culturing can be utilized in cannabis production in a number of ways including genetic preservation, pathogen identification, pathogen eradication, micropropagation, genome sequencing, and marker-assisted breeding.

Current State of Cannabis Breeding

You should now have a good understanding of the cannabis breeding process. This is a science that evolves daily, with new combinations being created, and offspring of those new strains being bred. Current strain trends show they are bred for higher THC percentages and flower yield from a commercial aspect; however, some newer strains are being grown for their specific terpene profile and yield. With the advent of medical marijuana and its plethora of uses for different ailments, there is a higher demand than ever for strains and terpene profiles that provide a specific medical purpose. Even though cannabis breeding has been around for quite a while now, it is exciting to think about all the possible combinations out there waiting to be discovered. At Seed & Smith, we pride ourselves on our grow team and the innovation they take when cultivating and breeding cannabis. Our passion for cannabis cultivation is fully on display for the world to see in our marijuana grow tour hosted at Seed & Smith’s state of the art dispensary in Denver, Colorado.

Learn more about our cannabis grow tour and book your experience today.


[1] Scitable – Gregor Mendel and the Principles of Inheritance

[2] Medicine Net – Medical Definition of Dominant

[3] Royal Queen Seeds – Basic Cannabis Knowledge: Genotype and Phenotype

May 27, 2020
Cannabis Education
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