Beginner's guide to cannabis varieties, genetics and breeding

Cannabis varieties breeding is the sexual propagation of cannabis plants by crossing two plants with each other. This can be done either with pure cannabis varieties or by crossing two hybrids. Cannabis breeding is usually done by experienced growers who want to create their own varieties.

If you have become a fan of a particular variety and have sourced it from different sources over a period of time, you have probably noticed a distinct lack of consistency. You may even find that a particular sample bears little or no resemblance to the cannabis variety you know and love. Of course, differences in growing techniques, environment and light conditions play an important role in flower development. But with exactly the same genetics, most experienced growers are able to produce results that are at least recognisable. Why then is it so difficult to find a match in different samples of the same variety? To answer this question, one has to dive into the murky waters of cannabis genetics and breeding.

Why is there so much variability between cannabis varieties?

Every spring, hopeful gardeners head to the hardware store to buy tomato seeds with names like Early Girl and Cherokee Purple, while visions of rich harvests of juicy purple fruit dance in their rain-soaked brains. While the outcome is hardly guaranteed, one thing is certain: all plants grown from a packet of seeds will produce fruit of the same size and taste. In the cannabis world, this is not the case. Tomatoes and most other garden vegetables are monoecious plants, meaning they have both male and female organs on a single plant. The cannabis plant is dioecious; it has separate male and female plants, the female being the one bred for its THC-containing flowers. Dioecious plants are more complicated to grow because you have to pollinate a female plant with a male plant. Seeds produced by cross-pollination of two plants have greater genetic diversity than seeds produced by self-pollination. In the case of the tomato, a staple food, breeders have devoted considerable resources since 1940 to breeding the fruit for commercial and home cultivation. Teams of scientists have spent years developing individual varieties and selecting for traits such as size, taste, pest resistance and drought tolerance. Almost without exception, they have also bred for uniformity.

Stabilizing cannabis genetics

Some cannabis breeders have also spent years breeding and crossing plants, often starting from a popular pure clone variety, to produce a seed-based variety that expresses the characteristics of one of the parents. Even in these efforts, however, there is some variation between specimens. You could germinate ten seeds and each would produce a plant that is slightly different in some way. The best of these seed varieties are quite expensive and highly sought after by commercial breeders, who often germinate 100 or more seeds of a single variety in order to select a plant that really matches what the breeder intended.

The vast majority of seed breeders do not even try to breed a uniform variety. Instead, they are simply looking for a stable genetic line, a so-called hybrid. These make up a large proportion of the cannabis varieties grown today, and it can take hundreds or even thousands of seeds to find one that has all the desired characteristics. Unless a breeder can find a true cutting of an original variety, it is difficult and time-consuming to produce the right genetics.

Truly great cannabis varieties gain their reputation among growers and consumers through reviews and word of mouth, with the best of the best gaining regional, national and even international notoriety.