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With so many amazing cannabis strains on the market, you might wonder how breeders go about producing new killer strains and how to breed your own strain. Breeding cannabis revolves around the “pheno hunt”, this is the process of selecting the best phenotypes of a certain (new) strain. A phenotype is the term for all noticeable traits of an organism, in this case those of a cannabis plant. While two plants may have the same parents, they will be different in a number of ways simply because they are not twins, but sisters.

Breeding cannabis will give you surprises like this: one plant is overfed while the other is thriving!

These two cannabis plants have the same parents, but their nutrient tolerance is clearly different!

Pheno hunting projects are attempts to isolate the very best version of a strain of cannabis, usually to produce seeds with that plant later. In our recent article “cannabis plant phenotypes and pheno hunting explained” we discussed the basic principles behind pheno hunting. In this follow-up article we aim to expand on that by discussing the 7 most important traits to look for during any good pheno hunt. We ranked these traits in the order we like to use, but keep in mind that a good strain can’t be weak on any of these fronts! Different strains are also bred for different purposes, so if you’re creating a CBD-rich medicinal strain you’ll probably be looking at different traits than if your only goal is to yield 2 kilos per light.

Pheno Hunting Trait #1 – Effect

As growers we love virtually everything about our favourite plant, but in the end it will most likely come down to how much we enjoy smoking/vaping/dabbing/eating the fruits of our labour. The differences between cannabis strains can be incredible and can range from bedtime knockout strain like our Afghani Gold to the energizing euphoric “good morning” strains like Spliffs Strawberry. The recent rise of high-CBD strains has also made it even more clear that the medical applications of cannabis don’t necessarily have to be connected to the effects recreational users are after.

Breeding cannabis is more and more focused on CBD content.
Breeding cannabis is more and more focused on CBD content.

Back when we only tested for THC, this strain wouldn’t have drawn much attention. However since the recent rise in popularity of CBD, this CBD Spliff Berry is one of our most popular varieties!

Crossing different strains is often inspired by wanting to mix two different effects, or to reduce one of the effects of a strain. A good example is our Jack F1, which combines the best medicinal effects of Northern Lights and Mexican Haze while losing a lot of the drawbacks of those strains. The uplifting, energetic high Mexican Haze gives is often paired with a sense of restlessness or paranoia. By combining Mexican Haze with Northern Lights, a strain that does not have this problem, we get the best of both worlds. Vice versa we had the amazing painkilling and relaxing properties of Northern Lights, but managed to reduce the couch-locking indica stone by crossing her with a sativa dominant strain.

Pheno Hunting Trait #2 – Smell And Taste

Aromas and flavours can be as important as the exact effect of a strain. If you’ve ever had a joint that was so pungent you made the whole party turn around, you know a strong smell definitely makes an impression. A specific smell and taste can make it a lot easier to identify a strain, so you know what to expect from cannabis that you didn’t grow yourself. We’ve also reached a point where many cannabis-connoisseurs are more interested in terpene profiles than potency. In the world of cannabis “haute-cuisine”, taste and smell have become incredibly important.

Smells and tastes can be deciding when breeding cannabis

Besides its upbeat and energetic effect, Spliff’s Strawberry is especially well known for its sweet strawberry aroma.

The most famous strains in the world are often named after their smell and taste, rather than their effect. Classics like Super Skunk, Cheese and Strawberry are good examples of strains that are renowned for their pungent nature.

Pheno Hunting Trait #3 – Growth Rate And Production

The first two traits we mentioned aren’t necessarily “commercial” traits, but growth rate and production definitely are. In this case production is the amount of dry weight produced per unit of time. This major variable strongly depends on the yield per harvest, but also on the (flowering) time a cannabis strain requires.

Increasing the amount of grams of dry cannabis per grow is always important when breeding cannabis. While quality is usually number one and people will often be more impressed by effect, taste, smell and look than by yield, cannabis is usually still sold per weight. Most grow rooms are built to achieve certain yields and there need to be good reasons to reduce these numbers. In a commercial setting growers will wonder if a super tasty strain that yields 20% less than they’re used to can also sell for 20% more. For a home grower lower yields could mean running out of meds early, which might not be worth the difference in effect, aroma and taste.

10-Week Strain

This Sweet ‘N Sour Indoor has been flowering for 3 weeks and is just starting to develop buds. (Thank you @white_widow_ww on Instagram).

The same goes for flowering times, as the flowering time of a strain directly determines its possible yield per unit of time. While an old-school haze-head might not mind waiting an extra few weeks before harvesting, most growers want to start trimming before their cannabis seeds have even germinated. Faster is better, and if you can finish a cycle in a week or two less, you might run a whole extra cycle per year.

Good examples of how much of a difference breeding has made in flowering times can be found in modern sativa-dominant strains. Classic landrace sativa strains from around the world are usually nowhere near the 8-12 week flowering period that we’re used to now. Take our our Royal Thai for instance, which has a flowering period of 11-12 weeks. This is only possible through selective breeding: its landrace ancestor can take more than twice as long to finish!

Landrace Thai takes forever to flower and doesn’t look as nice as the average indoor strain, but is otherwise amazing!

Another reason growth rates and flowering periods are becoming increasingly important is the rising popularity of autoflowering cannabis strains. Breeders often brag about how fast their autoflowering varieties go from seed to harvest, and we have to admit this has been a game-changer. While 10 weeks used to be an absolute minimum amount of time per grow, some autoflowering strains can do this in less than 9! Because of these short life cycles, growth rates during veg have also become more important. Small differences in growth rates early on can make a huge difference once it’s harvest time.

Pheno Hunting Trait #4 – Bud Density And Shape

Bud shape and bud density are enormously important features when it comes to growing cannabis and will largely determine the “bag appeal” of a strain. Dense, chunky nugs look better, are less likely to fall apart and will usually have a much better stem-to-calyx ratio than looser buds.

The structure of this Jack F1 bud is a great goal for any cannabis breeding project!

This Jack F1 bud is tight and dense, just the way we like it!

From a grower’s perspective denser buds greatly increase the potential grams per square meter of a grow and save a lot of time trimming. The shape of buds can also determine how well a strain of cannabis does in certain grow setups. Strains with long, candle-shaped buds for example are better in a SoG setup than if you were to scrog them. Bud density and shape also determine how easy a strain can be trimmed at harvest, which can be the most important cannabis trait for some growers!

The downside of dense buds is that they can become limited in their airflow, leaving them susceptible to mildew and bud rot. This is also the reason some of our outdoor strains are slightly “fluffier” than their indoor versions.

Pheno Hunting Trait #5 – Plant Shape

The growth form of a strain of cannabis seeds is usually mentioned in the description a breeder provides and can determine which strain to pick for your setup. Descriptions like “bushy, christmas-tree like cannabis plant” or “tall lanky sativa strain” describe the growth form. Sativa dominant strains will usually have thin, widely spaced leaves, a relatively large internode distance and become very tall. Indica dominant strains are known for their wide leaves, short internode distance and bushy nature.

Internode distance is very important in terms of how practical a strain can be grown, and how efficient lighting can be in an indoor grow. When the distance between nodes becomes too long stems are more likely to snap under the weight of the buds once they start reaching maturity. It also becomes much harder to use light efficiently as this increases the distance between the canopy and lower buds. The internode distance is a trait in and of itself, but also depends strongly on how much a cannabis plant stretches during early flowering. Shorter internodes and as little stretching as possible are generally preferred traits when breeding cannabis.

Purple Berry Kush pre-stretch

Purple Berry Kush pre-stretch

This beautiful Purple Berry Kush hasn’t started its flowering “stretch” just yet. Picture and plant by @Greendiamonds_est15 (instagram).

Purple Berry Kush post-stretch

Purple Berry Kush post-stretch

Purple Berry Kush can stretch quite a bit in the first two weeks of flowering. This picture was taken less than two weeks after the previous, un-stretched picture. Thanks again @greendiamonds_est2015!

When looking at the shape of a certain strain cannabis plants are often grown out without any training, topping or defoliation to see what their “natural look” is. This way we get a clear image of how many side branches are formed and how well these compete with the main cola. This way strains can be bred to grow in a certain shape. Breeding cannabis will often be geared towards making plants bushier as this makes them more suitable for low stress training and scrogging. Conversely outdoor strains need enough internode distance to allow for proper airflow.

Pheno Hunting Trait #6 – Resistance

The last but certainly not least category of traits in this list is resistance to hermaphroditism, infestations and swings in environmental conditions. While some argue that swings in environmental conditions should not be an issue, we feel that life is not always perfect. At Spliff Seeds we like to make sure that a few days of lousy weather or a day without a dehumidifier won’t ruin your entire crop.

Big Gold Rush Outdoor

This Gold Rush Outdoor has a massive yield and grows vigourously, but without disease and pest resistance this wouldn’t be much of an outdoor strain at all!

Many top-selling strains are very difficult to grow as they can be affected strongly by changes in the environment. Heat and humidity can cause a cannabis plant to produce less potent, fluffy buds. Nutrient solutions with an incorrect EC and pH can even kill off a cannabis plant in a matter of days and have ruined the ambitions of many beginning hydroponic cannabis growers. Every cannabis strain has its nutrient “sweet spot”, but there is a large difference in how a cannabis plant reacts when EC and pH values aren’t perfect. Because of all this variability, we will keep breeding cannabis strains that can withstand a changing environment and still provide a quality harvest.

Some strains of cannabis are also very likely to become hermaphrodites and can make it very difficult to keep your buds from being filled with seeds. Hermaphrodite-prone cannabis strains can easily be missed during while breeding cannabis if this is done in a hurry because feminized cannabis seeds are produced from hermaphrodite cannabis plants anyway.

Finally every grower will agree that finding bugs, mildew or bud rot on your flowering cannabis plant is a terrible experience. People tend to forget that these threats are constantly developing to become even better at colonizing your cannabis plant. Just like with the virus scanner on your computer, cannabis plant resistance genes need to be “updated” regularly to stay ahead in this biological arms race.

frosty AK cannabis bud

Thanks to her very diverse genetic background, our AK is one of the most mold/pest resistant and durable strains available! This ensures that beautiful frosty buds like this one are within reach with any level of experience!

Good Luck Breeding Cannabis

With this overview of the different cannabis traits we like to look at for breeding cannabis strains, we hope to have given you some insight in what a breeder looks for in a cannabis plant. Once you figure out which traits you’re looking for the process of breeding cannabis isn’t that complicated, it just takes a lot of time and work. Keep in mind that some of the most popular strains in the world were discovered by accident, so you might stumble upon the next big cannabis strain yet! If you ever do find that magic pheno make sure to take clones! And if you’d rather stick to growing and avoid breeding cannabis all together, we’d like to remind you that our seed catalogue is full of strains that we have already put through this process! Either way, Spliff Seeds wishes you the best of luck growing and breeding cannabis!