• Post last modified:August 7, 2022
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There are over 700 strains of Cannabis today, and as a grower, you may find it challenging to keep up with the various strains and choose the one that suits your needs. But how did we get here from a few native cultivars spread across Asia, Africa, the Middle East, and Latin America?

Some commercial breeders have spent over twenty years crossbreeding and perfecting Cannabis varieties to produce unique strain that harbor desirable characteristics. However, if you are a grower and want to breed your own strain at home, it doesn’t have to take that long; it can be done in just a couple of grow cycles.

You can create new strains at home if you understand the basics of Cannabis breeding. Cannabis breeding is essential to develop new and unique cultivars with better traits, aroma, flavor, cannabinoids, and yields. Experts also crossbreed several strains to strengthen good characteristics such as disease and bug resistance, early maturation, etc.

So how do you create new strains of marijuana? You don’t need special training or a degree in plant production to be a good Cannabis breeder. However, you need to understand how the process takes place and the requirements for crossbreeding, purification, strengthening, and storage of new genetics.

How To Breed Cannabis Plants

For most growers, the most important marijuana plant is the female. However, males are equally essential to when it comes to breeding.

To breed a Cannabis plant, you need a male and a female plant. The male produces pollen that fertilizes the female flowers. A non-fertilized Cannabis plant produces sticky buds that we collect, dry and smoke. However, when you are growing for purpose of breeding, instead of smoking the flowers you pollinate them using the male plant and the buds then produce seeds.

These seeds are a hybrid of the male and female parent plant. Suppose you have discovered strain X of cannabis that produces particularly high yields but has low potency. At the same time, you have a strain Y with medium yields but high. Simply by using the pollen from one to pollinate the flower of the other you can create a new strain with the desirable qualities of both plants.

How do I decide which strain will be male and female during the breeding process?

The offspring carries more genetics from the female parent than the male parent. Looking back at our example, if your goal is to get a strain with higher yields or potency it is best to decide which of these is the most important characteristic to you and that would be the female parent you choose.

The Breeding Process

To start the breeding process, select your male and female strains appropriately. Grow the male and female plants in separate grow chambers for several weeks until they start flowering. This phase is known as the vegetative phase. Typically, most strains will take between 6 and 10 weeks to before they flower.

Once the plants are large enough you can trigger flowering by switching the light cycle to 12 hours of light and 12 hours of darkness. The male plant will start producing whitish and hairy stamens that produce pollen. On the other hand, the female will start producing pistols that will eventually develop into bud-sites.

You will notice a few weeks into the male flowering stage that it will begin to develop its pollen sacks. These typically begin to develop 1-2 weeks before the females begin flowering. Once you see the pollen sacks beginning to crack open, it means they are ripe and ready for harvesting.

How to harvest and collect male pollen

One male plant can pollinate up to 20 female plants. For best results, place the male plant at the center of the chamber and surround it with the females. There are three primary ways to pollinate your female cannabis plants:

  • Applying collected pollen on the female flower
  • Placing the male at the center of the chamber and shaking it to release pollen
  • Using brown paper bags
growers harvesting cannabis plants
Outdoor cannabis farmers harvesting plants

Applying collected pollen onto the female flower

This is common among home growers and commercial breeders, you collect the pollen using bottles, small bags, or jars, then use a soft toothbrush to pick the pollen and brush it against the pistil of the female plant.

  1. When the male plant is ripe collect its pollen by shaking it into your chosen container.
  2. Once you have collected enough pollen in a container, take it to the female plants you wish to pollinate and use a paintbrush to carefully apply pollen dust to the female flowers.
  3. Allow a few weeks and you should begin to notice that the female plant will begin producing seeds.

This method is the least messy and is great if you are growing other female plants within the vicinity that you do not want to pollinate.

Placing the Male Plant at the Center and Shaking It

A healthy male plant can pollinate several females. This method can be messy, but is effective at quickly pollinating multiple female plants at once.

  1. Put the male plant at the center of the grow chamber, surrounded by the female plants.
  2. You then find a way to shake the plant vigorously until the chamber is filled with pollen dust from the male plant. For instance, you can tie a string or rope around the male plant, pull the other end of the string away, then shake the plant from a distance. Pollen dust will fill the grow room and settle on the surrounding female flowers where fertilization will begin.
  3. Give the pollen up to an hour to settle around the female plants. When the pollen is well distributed among the females, take out the male or gather the females to grow in a separate chamber.

Collecting pollen using Paper Bags

This method is more precise and if you are growing multiple strains, it is the least messy way to do things.

  1. First cover a male branch along with the pollen sacks with a bag.
  2. Shake the branch so that the pollen is collected in the bag.
  3. Next take the bag off the male plant and carefully place one of the flowers of the female plant into the bag.
  4. Secure the bag onto the plant, then shake the bag. Wait for the pollen to settle on the female plant for a few minutes. If you want to pollinate just one female using pollen from male plants, this method is the most suitable.
  5. Now just wait, you should notice soon that the flowers will begin to produce their own seeds.

Cloning Cannabis Strains To Preserve Genetics

Cloning is a process that creates a new plant from a branch of a healthy female Cannabis plant. You can clone a new plant from a plant that germinated from a seed or another clone. To do this you would cut the stem of a healthy marijuana plant and dip it into a growth medium with a rooting hormone.

After some time, the branch begins to produce roots. You can then transfer the new plant to a growth chamber, where it develops into a healthy marijuana plant.

Cloning preserves the genetics of a specific strain and is a form of breeding, however unlike breeding with pollen, cloning is simply preserving the genetics of one plant. The clone will contain the identical genetic make-up as the parent. The great thing about cloning is that you can keep cloning and multiplying your favorite Cannabis strains as long as the parent plant is healthy.

clones in a grow room
Cannabis grow room containing transplanted clones

How F1 Strains Are Created

FI stands for filial 1 hybrids, which refers to the first generation offspring of the parent strains. Suppose you crossbreed strain A and strain B. The offspring will be an AB strain with genetic straits from both parents. AB is the FI strain in this case.

These generations can go up to the 5th generation by inbreeding the offspring, something that strengthens and stabilizes the genetic and phenotypic traits of the daughter strains. This leads to heterozygosity, a phenomenon that describes the unpredictability and diversity of the phenotype of cannabis strains.

So how are F1 strains created?

F1 strains are created by crossbreeding two parent strains. Back to our example, you get an AB strain by crossing strain A with strain B. Crossing, in this case, represents a strain A male pollinating a strain B female. When the fertilization is successful, and strain B female produces seeds, these seeds will be an F1 strain composed of genetics from the father and the mother strain.

You can inbreed F1 strains from different combinations to create F2, F3, F4, F5, and inbred lines (IBLs). These new generations are known as poly hybrids and are heterozygous and are less stable.

Backcrossing Genetics

Remember how we’ve said crossing an F1 strain with another F1 strain creates heterozygosity and instability? That is a problem in Cannabis breeding. Polyhybrids tend to have unpredictable genetics, which is reflected in the plant’s phenotype. Inconsistent phenotypic traits are bad news for commercial growers, and I some home growers don’t want plants with diverse cannabinoids, aromas, or appearances.

That is where backcrossing genetics comes in. Backcrossing genetics is a process where you crossbreed the new strain with itself or its parent. In our example, backcrossing would entail crossing AB with another AB strain or crossing it with B. In the first scenario, you would use pollen from an AB male to pollinate a female AB plant.

In the second scenario, you would use pollen from a male strain A to pollinate the female plant of strain AB.

Backcrossing stabilizes the genetics of a strain and makes its phenotype more consistent. It leads to homozygosity which is essential to commercial breeders. Homozygous strains exhibit similar phenotypic traits. These phenotypes include leaf color, bud and plant size and structure, chemical composition, and resin production.

This type of breeding produces high-quality cultivars. However, both desirable and recessive genes are strengthened and stabilized. If your strain has an undesirable recessive gene, backcrossing perpetuates the negative trait, passing it down to subsequent generations. For this reason, carefully choose your parent strains during the backcrossing process so that you only pass down the most desirable genetics.

To sum up, cannabis breeding can be incredibly useful at keeping strains with the most desirable traits going by creating new strains. You create new strains by bringing together a male and a female marijuana plant. The male produces pollen that fertilizes the female plant. The female plant, in turn, produces seeds containing genetics from the male and female plants.

You can also preserve desirable strains through cloning, whereby you cut a branch from a healthy female plant and dip it into a growth medium to stimulate root growth.

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