How to Crossbreed Cannabis

Cannabis is an amazingly diverse plant, with thousands of officially recognized strains and thousands more that aren’t well known. Different strains grow better in different environments, look different, and have different effects. Crossbreeding cannabis has given us an incredible amount of choice in the specifics of the plant we consume, and breeders are constantly working to create even more strains and variations.

If you’re a grower, you may have considered trying out crossbreeding – after all, how cool would it be if you could take your favorite strain, cross it with another strain you love, and end up with something even better? The basics of crossbreeding sound simple, but the specifics can get extremely complicated. It’s a tough task that is most easily accomplished by a whole team of growers in a large space, but it can also be done at home.

What is Crossbreeding?

Crossbreeding means taking a male plant from one strain and a female plant from another strain and allowing the male plant to fertilize the female. When the female plant later produces seeds, those seeds will express genes from both parent strains.
Typically, the mother’s genetic traits will carry over to the new hybrid more completely than the father’s. For that reason, many breeders recommend that you start with a female plant’s traits in mind as the “primary” traits you want to develop, and then pick a male plant with traits that should be complementary.

How to Pollinate Cannabis

A few weeks after female plants start growing white pistils, they’re ready to pollinate, and there are two ways to pollinate them. The first way – the simple way – is just to leave all your plants in a room together. The male plant will grow pollen sacs early on in its flowering phase. When it releases pollen, it can absolutely cover 20 female plants.
Just make sure you keep all your plants in an airtight environment to make sure that the pollen does its job fertilizing the other plants, and doesn’t create an allergy-inducing mess all over your house. If you have a grow space in your room and don’t want to fertilize every plant, you’ll need a separate breeding chamber.

The second way of fertilizing is more hands-on. You’ll want to take a seal-able plastic bag and collect the male plant’s pollen in it. Then, you’ll want to separate the female plant you want to fertilize from the others, and make sure the air in the room is still. Then, take the plastic bag and seal it over one of the female plant’s stems. Shake the bag to cover the bud with pollen, wait a few hours, and then remove it.

The Hard Part About Crossbreeding Cannabis

Unfortunately, this is just the beginning of the process of creating a new strain. The seeds you harvest from your fertilized female plants are now a hybrid of both parents, but they aren’t all identical.
Think about how human genetics work: If two parents have six children, each of those children will look different (assuming there are no identical twins, a rare occurrence). This is how it works with cannabis, too – each of your new seeds has a somewhat different blend of the genes that the parents provided.

These different genetic blends are called phenotypes. A plant with multiple phenotypes is heterozygous. As a cannabis consumer, that isn’t what you want. If you walked into a dispensary and bought what you thought was your favorite strain only for it to smell, taste, and feel totally different, you’d be disappointed. What you want is a strain that is homozygous, meaning that all the children are the same. To do that, you’ll want to select your favorite phenotype out of a batch of child seeds and then start backcrossing it.

Backcrossing Cannabis

Backcrossing is essentially inbreeding. The goal is to remove unwanted genes from a plant’s lineage by breeding your new hybrid either with itself or with one of the parent strains, over and over, until you get a strain that is stabilized, meaning that each plant is either genetically identical or nearly identical. This can take generations, but it’s worth it.

Finally, remember to take notes and label all of your plants and seeds. Cannabis breeding is a difficult and lengthy process – you’ll thank yourself if you can keep if from being confusing, too. Happy breeding!