Cannabis Genetics 101: The Birth of a Bud

Perhaps you’ve acquired a favorite strain of cannabis over the years, or perhaps you’re overwhelmed with the immense array of options on the market. Indeed, there is a growing variety of cannabis, with current estimates suggesting there are over 3,000 different strains! How are these strains different from one another, and what are the secrets to cultivating a delicious and powerful strain? To answer these questions, we must explore the art and science of breeding cannabis plants.
Breeding cannabis is much different than breeding common garden herbs or vegetables. Most garden vegetables are monoecious, which simply means they have both “male” and “female” organs in a single plant. Cannabis, however, is dioecious, meaning a single cannabis seed will grow into either a “male” plant, or a “female” plant (or on occasion, an intersex plant). Interestingly enough, the sought-after resin coated buds of the cannabis plant are actually its reproductive organs. With male cannabis plants, sacks of pollen grow where buds are expected, and once the plant reaches full maturity, the sacks of pollen explode and fertilize any surrounding cannabis buds. If you’ve ever gotten a bag of weed with seeds in it, it’s because a male cannabis plant was close enough in proximity to pollinate the female plant.

Seeds from two cross-pollinated plants present more genetic variation than seeds generated through self-pollination, hence the wide array of cannabis strains. Those who attempt to create new strains from cross-pollination can spend months caring for seedlings before finding the cannabis plant with the ideal, and most highly sought-after qualities. For this reason, most cannabis growers will use cuttings of female plants that are known to produce high-quality buds. A cutting of a young branch from a cannabis plant can be rooted and re-planted, effectively creating a replication, or “clone,” of the original plant. This method is much easier than sprouting from seed, and is less costly and time consuming.

Part of the complexity of breeding dioecious plants from seed comes from the prevalence of certain dominant genes, and the infrequency of recessive genes (if you happen to remember Punnett Squares from high school biology class). This means that cannabis plants with certain qualities, say, for instance, a short bushy purple plant, can still have the genetic information for a tall, green, stocky plant, but if the genes for those qualities are recessive, the plant will most likely be short, bushy, and purple. The ugly surprise comes from breeding two short, bushy, purple plants, and surprisingly growing a tall, green, stocky plant- many people are surprised by this, but cannabis plants still carry the genetic information for recessive genes, even if they aren’t present characteristics. This is exactly the same as two blue eyed parents giving birth to a brown eyed baby- both parents can still carry the gene for brown eyes even though they have blue eyes. Biology is fascinating!

What this means for breeders is taking into consideration the lineage of a cannabis strain intended for breeding, and the variety of possible characteristics one can grow. Many cannabis breeders will have to grow hundreds of offspring, only to select one or two plants with the most desirable qualities. Thanks to the patience of cannabis breeders, the tricky work is done for us and we have the luxury of buying the most potent cannabis available without having to sacrifice months or years to curate those highly desirable qualities.