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How Do Breeders Cross Strains? 

Created by
JoshuaHolt JoshuaHolt
Added 25 October 2021

Have you ever admired a particular cannabis strain and wondered where it might have come from? There are so many cannabis strains with multitudes of traits that it's natural to question how they inherited those genes. How do breeders create so many beautiful strains, and how does it all begin?

In this article, we will explore the intricacies of breeding cannabis and much more.

What Is Cannabis Breeding?

breeding cannabis

Breeding cannabis plants begin with crossing female and male strains to produce a new hybrid strain. But why do breeders create new strains in the first place? The primary reason is to enhance the positive qualities of two plants or create something better than the parent strain.

Every strain has specific characteristics that are better than the others. Similarly, it may have a few flaws or drawbacks. Like humans, no strain is perfect. However, the breeder can reduce its unfavorable characteristic by crossing with another strain.

For example, strain A may emit a fantastic aroma, but it may exhibit poor resistance to diseases and pests. On the other hand, Strain B may lack aroma, but it makes up for it with its resilient nature towards pests. As you can understand, both strains have a unique quality that can enhance the user’s experience. In such cases, the breeder may cross both strains to create an offspring that not only smells wonderful but is super resistant as well.

In a nutshell, cannabis breeding is a great way to improve the performance of a particular strain by crossing it with another. Unfortunately, although it sounds simple, it’s not so easy. It can take years for breeders to cross strains that produce consistent seeds. 

What Is The Importance Of Breeding?

Breeding is the pillar of modern cannabis strains. It's the reason why you still see seeds from the 70s.

Mr. OG, or OGD, as he’s fondly called in cannabis communities online, tells us about his years of experience as a breeder. As the founder and owner of Connoisseur Genetics, specializing in seeds collected and bred from different parts of the world, OG says he spent a good portion of his life breeding exotic strains to preserve their genetics. 

“I’m most known for my work with Haze and my SSSDH cut known as the OJD cut found in a Super Silver Sour Diesel Haze seed pack from a Reservoir seeds release around 15 years back.”

As you can see, breeders are proud of their work. It may even take more than a decade to breed several top-class strains; however, breeders don’t mind as long as the results are satisfactory. 

Some strains are so spectacular that you're probably growing them even today. If breeders didn’t bother to work on the strains, we wouldn't be able to experience the magic of landrace and other ancient strains that ruled the cannabis circles in the 70s and 80s.

Breeders that are serious about their work will also give you more information about the strains because of their detailed process. While buying seeds, you'd want to know everything about them. Where does the strain come from? What qualities does it possess? What strains make up this particular strain? 

You want all the details about its genetics, and you get it only from the breeder who has spent considerable time working on the strain. Without this information, you'd be clueless about the seeds. Fortunately, cannabis breeding helps breeders track the progress of a strain and make it available to others.

The Fundamentals Of Breeding Cannabis


Although cannabis enthusiasts are most interested in female plants due to the buds, male plants are equally important. So unless the breeders are trying a technique called "selfing,” they start with two male and female plants to create new phenotypes.

Take the example of a popular strain like Sour Diesel Haze, for instance. The breeders began the process by crossing Sour Diesel with a Haze cultivar because they probably admired a few attributes of both strains. In short, they were trying to create a better version of the parents, which ultimately resulted in Sour Diesel Haze.

To cross both strains, the breeders pollinate the female plants using the pollen from the male plant. Then, they collect the seeds from the female and grow them separately, creating several phenotypes in the process. Although the offspring come from the same parents, you will find differences. As you can see in the pic above, two strains can produce offspring that are different in many ways, including color, size, aroma, and many other factors. 

OGD asserts that the female traits are often more dominant in the offspring.

"A female's traits are dominant in the phenotypes, but it's equally important to choose strong males to get great results." 

Crossing one resilient strain with another won't get desired results immediately. So, how do they do it?

How Do Breeders Breed Cannabis Plants?


OGD explains how they breed plants. "First, we choose a male plant with strong attributes. Then, we choose numerous female plants and put them all in an enclosed space, so the plants outside are not affected by the pollen."

Technically speaking, you can even breed cannabis plants at home, provided you dedicate some space for them. Commercial breeders use huge facilities because they indulge in several projects simultaneously. However, if you want to cross only a few plants with each other to preserve the genetics, it's possible to do it even in small spaces.

While you can pollinate several female plants, you won't need more than one male plant because a bit of pollen goes a very, very long way. Male cannabis plants in the wild have no problem pollinating female plants that are miles away from them. 

In addition, it's easier to track the progress of the phenotypes with one male rather than using several males and females simultaneously. With one male, you're sure that the pollen comes only from that male, but if you have several male plants, the pollen could get mixed, and you might end up with phenotypes with undesirable genetics.

So, once the plants are placed in the breeding room, you can immediately switch the plants to the flowering stage to get pollen from the male. Once the male produces the pollen, it will pollinate all the female plants in the vicinity. Or, you can transfer it to the pistils manually with a brush. At this stage, it makes sense to store the pollen in the freezer, just in case you need it in the future.

When the female plants are mature, you can collect the seeds. Note that it takes at least 3-4 weeks more than the period required to harvest buds.

Once the seeds are harvested, home growers may stop since they have achieved their goal of crossing two strains. So now, you have a bunch of seeds you can grow, and while all of the seeds may not be similar to their parents, you will find some that are just as good.

However, for breeders, the process of breeding is a long journey. Unlike home growers, they need to cross the phenotypes repeatedly to get the hybrids they desire. In simple terms, they need to ensure that their seeds are resilient and consistent with being commercially viable.

Why is it a long process to breed strains? Well, one of the primary reasons is that the phenotypes all differ from each other. Some may be strong, some weak, some very aromatic, and others could be complete duds. Every seed will exhibit a unique characteristic, and it's up to the breeder to choose plants that suit his requirement. 

The offspring with differing attributes are called phenotypes. If these phenotypes are very different with various characteristics, they are known to be heterozygous; however, breeders desire seeds with a homozygous nature, which means that they want plants that are similar to a great extent concerning genetics. 

For example, when a cannabis grower purchases ten seeds from the breeder, he expects most seeds to show similar characteristics.

Coming back to phenotypes, the breeder will then choose some phenos that show unique qualities. For instance, imagine strain A is aromatic but lacking in trichome production. Conversely, strain B produces ample resin but is less aromatic. When crossed with each other, the resulting phenos may display both characteristics, making the breeder very happy. 

Some phenos may be different from the parents too, and the breeders will discard them. However, once the breeder selects the offspring he likes, they are grown and tested repeatedly to ensure that the resulting seeds are worth the customer's money. 


In addition, the breeder crosses his favorite phenotype with the original strain. Also called backcrossing, it's done to strengthen the genetics and make it homozygous.

Finally, the breeder will proceed to prepare the seeds of the phenotype he chose after many tests. Generally, they are stored in freezers in vacuum tubes to enhance their longevity.


There's a story behind every seed you purchase. The breeder puts in years of work by constantly strengthening the genetics of his favorite strains. Thanks to them, we also have landrace strains bred with many modern strains, offering us the best of both worlds.

While you can create your own strains at home, remember that it could be a wild-goose chase, and all your hard work can be for naught if everything doesn't work as planned. However, it may work for short-term purposes, and you also get the satisfaction of trying something new.