Growing cannabis can be rewarding for many reasons. Here we go over cannabis breeding 101: growing cannabis for seeds. Learn how cannabis breeders combine strains to enhance, strengthen, or combine traits & effects of cannabis to create the perfect experience. Use this technique to create your own cannabis strains and breed weed seeds to preserve genetics – or cross-breed some more!
Cannabis Breeding 101: Growing Cannabis for Seeds
Growing cannabis can be rewarding for many reasons. Whether it’s home growing or commercial cultivation, the monetary payoff can be great, not to mention the personal satisfaction and fun derived from this practice. Although some home growers use clones in their gardens, the majority use seed, and there is a brisk market for seeds from elite strains. Although some seeds can be very expensive, in the hands of competent growers, they will produce consistently potent and flavorful flower.
It takes experience and skill to create strain-specific seeds that produce a small number of phenotypes that produce fine examples of their strains. While stabilizing a strain in seed form takes considerable time and space, creating excellent crosses at home is much easier, and the results can be quite impressive. The result of crossing two strains will usually produce plants that have the qualities of one parent or the other, but some of them will capture some of the finest traits of both—and this is what home growers should strive for when creating their own crosses at home. For instance, crossing a diesel strain with a fruity indica or sativa can result in a unique, potent and tasty cross that has a fruity aroma with recognizable diesel fuel notes. The best examples of a cross like this are the ones to clone and enjoy in future grows by keeping the mother plant healthy and happy. With a good mother plant, you can share your creation with other growers and expand the genetics in their strain catalogs.
Creating high-quality seeds at home doesn’t have to mean committing the entire grow to seed production. It is very easy to produce outstanding sinsemilla (seedless) flowers, while simultaneously creating seed. Read further to learn more about how this is done, and how you, too, can become a cannabis breeder within the confines of your home grow.
Understanding the Basics
To produce seed, of course, you will need both a male and female plant(s). Crossing a male and female plant of the same strain will produce F2s (second filial generation) seeds of that strain that will be less consistent than the F1 seeds used to produce them. We won’t broach that topic here since it’s a separate topic all its own that deserves separate explanation and attention. Instead, we’ll detail the way to create strong crosses from two separate strains to produce something new and different.
To produce these crosses, you will have to grow seeds from at least two distinctly different strains. This type of cultivation project will require growing from normal seed rather than feminized seed since the objective is to produce both male and female plants. This is best accomplished in a grow space that can hold several plants.
When growing normal seed, the vast majority of the time the objective is to identify the females once you decrease the photoperiod. Once the females are identified, they are retained for flower production and the males are discarded. When growing for seed production, however, the males that are grown are just as important as the females, and both sexes are retained.
First, you will need to obtain seeds of the two strains you wish to cross. There are many seed banks and brokers from which to purchase your genetics. Decide whether you want your grow to produce indica seeds, nice balanced hybrid seeds, or sativa seeds, then buy two strains to accomplish that goal.
The strains you choose is a very subjective decision based entirely on your personal preferences. Do you like dank, skunky indica? Is a berry-flavored hybrid more to your liking? How about a piney and minty sativa? A large part of the fun of breeding cannabis is matching up strains. Sometimes crossing two very different strains results in something entirely new and different. It pays to put some thought into which two strains you will use for your breeding project.
Learn How To Grow Cannabis!
When you begin your grow for seed production, you will begin in the regular manner, growing your normal seeds rather than feminized. Once the lights are switched to a shorter photoperiod (12:12 light-to-darkness), the plants will typically reveal their sexes within approximately one week.
Once the plants show signs of being either male or female, you must separate them and grow each in different locations that are well apart from each other. Males must be isolated from females. Ideally, you want to grow at least a few plants of both sexes, eventually selecting the best of each for breeding. The male with the best plant structure, resin production on stems, and the strongest terpene odor is the one to choose. Males have less-pungent terpenes than females, but usually some odor can be detected, even if it takes rubbing the plant stem gently with your fingers and then smelling them. As well as good overall plant structure, you want to select a male with good leaf structure. Males with thinner leaves are desirable because if his female offspring have wide leaves like him, the leaves will shade developing flowers and thwart their growth and development.
If a male releases pollen when left in a grow room with females, it will ruin a good seedless crop. Even pollen on hands and clothes can fertilize and seed a good female. If a male is left in a grow room with females and releases pollen, it will result in literally thousands of seeds from heavily pollinated females, rendering the flowers useless for anything but seed production. Heed this warning. For this reason, when growing both female and male plants, the best practice is to visit and water the female plant room before attending to the males. Under ideal circumstances, both sexes will be grown under HID or LED lights. For the home grower with limited resources, however, there is another option. Place the male(s) in a room with a large window that receives good sunlight. The males will mature to the point that they release pollen for collection. Then, following collection, you can dispose of them.
Pollen Collection and Pollination
Once your chosen male is releasing pollen for a few days, it’s time to collect it for use and storage. The easiest way to do this is to position sheets of aluminum foil under the male branches that are producing pollen. Shake the branches until pollen collects on the foil. The pollen should be yellow in color. Collect the pollen in a small container for immediate use and later storage.
There are a variety of ways to pollinate a female plant, but the information contained here is perfect for a home grow. It will allow you to produce a significant quantity of seeds and also produce seedless flowers for smoking or vaping. This pollination method will require the use of a small paintbrush.
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To pollinate the female plant(s) of your choosing, you want to utilize some of the lower buds that have been flowering for only three weeks or so. By pollinating the flowers on the lower branches, you will still be able to harvest the choice colas at the top of the plant. If pollinating the upper flowers, you also risk seeding the entire plant from pollen that drifts down to the lower branches.
There are a variety of ways to pollinate the selected flowers, including methods that include the use of plastic bags. One of the easiest and most effect methods, however, utilizes a small paintbrush. Simply dip the paintbrush into the pollen container and gather some of the yellow pollen. Then, brush the pistil hairs on the lower flowers of your choice. By pollinating just a few buds, you will soon have anywhere from dozens to hundred of viable seeds for later cultivation projects. Allow the pollinated flowers to mature for at least six weeks. If you wish to harvest the upper colas and unseeded buds before that time, by all means do so. Just retain the seeded buds so they can continue to mature. The quality of the seeded flowers will be very low and of little value for consumption purposes. After you harvest and dry the seeded buds, break them apart on a level surface and collect the seeds. Store the seeds and any remaining pollen in a cool, dark place, where they will remain viable for an extended period of time.
Creating your own cannabis crosses is a fun and worthwhile endeavor. If you combine quality genetics, you will come up with something new and different in which you can take pride. The potential for greatness exists in every unsprouted seed. Imagine the possibilities!
Cannabis Breeding: How Are New Strains Created?
While browsing Leafly’s strain database, you may wonder what a cross of this and that strain is, what a hybrid or a backcross is, or what a parent strain is. All of these have to do with plant breeding—essentially, breeding a male and female plant to combine or refine the genetics of two plants or strains. Breeding two different strains often results in a new strain, or hybrid.
Cannabis breeders typically breed to purify and strengthen strains, combine strain traits, or enhance specific characteristics.
Cannabis breeders typically breed to purify and strengthen strains, combine strain traits, or enhance specific characteristics like higher yields, specific aromas, potency, and many other things.
When growing and breeding, it’s important to know where your seeds come from and what kind of genetics they have. If the seed breeder can’t give you a detailed history of how a packet of seeds was bred or what they were crossed with, you never really know what you’re getting.
Plant breeding is a fundamental process of growing cannabis. Breeding is highly technical and typically done on a commercial scale, but with legalization increasing, breeding is becoming more popular. You can even do it yourself.
The Basics of Breeding
Cannabis plants can be either male or female. Cannabis consumers are mainly concerned with female plants, because only females produce the sticky buds that we all know and love. But male cannabis plants are important for the breeding process, as they are needed to pollinate the bud-producing females.
Take the strain Super Lemon Haze as an example. It’s a hybrid (or a “cross”) of Super Silver Haze and Lemon Skunk—these are the parent strains. At some point, the breeder decided that they liked some attributes of Super Silver Haze and some of Lemon Skunk and decided to combine the two.
To do this, you need a male of one strain to pollinate a female of the other. Once pollinated, the female will then produce seeds that express the genes of both the male and female plant. Those seeds will be harvested and grown separately, and voilà: You have created a hybrid.
So how do you know whether to pick a male or a female of each strain that you’re crossing?
“Often in cannabis, the traits of the female carry over to progeny (seeds) more than the male. That said, the traits of the male are often obvious to the discerning grower so one should definitely choose a male that will complement the traits of the female,” says Nat Pennington, founder and CEO of Humboldt Seed Company who’s been breeding cannabis for 20 years. “So much is possible with truly intentional breeding strategies.”
How to Breed Cannabis Plants
After two parent strains are selected for breeding, a male and several females are put into a breeding chamber to contain the pollen. A breeding chamber can be as simple as an enclosed environment with plastic sheeting on the sides, or a specially designed sterile environment for large-scale breeding.
“A healthy male can pollinate up to 20 females, and by pollinate, I mean absolutely cover the plant with seeds.”
A single male plant can pollinate tens of females. “It’s always a good idea to have only one male, genetically speaking, per pollination effort,” says Pennington. “A healthy male can pollinate up to 20 females, and by pollinate, I mean absolutely cover the plant with seeds.”
This is intentional breeding—any grower who’s accidentally grown a male and pollinated a crop will know that one male can easy pollinate hundreds of females, filling your whole crop with seeds.
Once in the breeding chamber, you can grow the plants vegetatively for a few weeks to let them get bigger, but it’s not necessary. Put them on a flowering light cycle: 12 hours of light, 12 hours of dark.
The mature male will grow pollen sacs within the first couple weeks of its flowering phase. Pollen will release from the sacs, move through the air, and land on the female plants, pollinating them. Having an enclosed breeding chamber is important to contain the pollen and also to prevent outside pollen from getting in.
You can also help along the pollination effort by shaking pollen from the male onto the females, or by collecting pollen from the male and directly applying it to the females. These female plants will continue to grow and flower, during which they’ll grow seeds (as well as buds). These seeds will express the genetics of both the male and female plant.
When the seeds are mature, they are harvested and stratified (or dried). “The secondary process of maturation happens after the plant is dead, and the seed needs to be stratified before it will germinate,” says Pennington. “In general, harvest for flower takes place three to four weeks before harvest for seed.”
These seeds—now a hybrid of the two parent strains—will be grown on their own, outside of the breeding environment.
But the process doesn’t end there. The hybrid strain that you buy at the dispensary has likely gone through many rounds—or generations—of breeding to strengthen its genes and to ensure that its descendants are healthy and consistent.
Just as you and your sibling might have different physical attributes from your parents, each seed created from a round of cross-pollination will have different attributes from its parent strains. Maybe you have your father’s eyes and your mother’s hair, but your sister has your mother’s eyes and hair. Each cannabis seed is unique and will express different traits, and different combinations of traits, from one or both of the parent strains. These seeds with various expressions are called phenotypes.
Homozygosity ensures that a plant will consistently produce the same seeds with the same genetic makeup over and over again.
A plant that produces a set of phenotypes that have a lot of variety are said to be heterozygous. With cannabis, you typically want seeds that are homozygous—ones that have the same set of genes. Homozygosity ensures that a plant will consistently produce the same seeds with the same genetic makeup over and over again, ensuring that buyers and consumers will get the same plant or seed time and again.
After a strain is crossed, a breeder will then have to select which phenotype of the new strain they like best. For large-scale growers, they want to choose the best phenotype for mass production.
Back to the Super Lemon Haze example: This strain takes a lot of its bud structure, trichome and resin production, and overall appearance from Super Silver Haze. But it takes its flavors and aromas from Lemon Skunk.
Lemon Skunk also tends to grow extremely tall and has loose buds, whereas Super Silver Haze grows smaller and has denser buds. Through selecting specific phenotypes, a breeder can pick one that has the attributes they want to keep. In this case, a phenotype that has the structure and bud density of Super Silver Haze and the flavors and aromas of Lemon Skunk.
Most likely, there were early phenotypes of Super Lemon Haze that grew tall and loose like Lemon Skunk, or tasted more like Super Silver Haze. But the breeder discarded those phenotypes and keep growing the ones that have the attributes of what we now know is Super Lemon Haze.
High-quality breeding still doesn’t stop there. Once a breeder has crossed a strain and narrowed down a phenotype and finally has the one, they will usually backcross that strain to strengthen its genetics.
Backcrossing is a practice where a breeder will cross-pollinate the new strain with itself or a parent—essentially, inbreeding the strain. This makes the strain more homozygous, and strengthens its genetics and desirable characteristics, and also ensures that those genes continue to pass down from generation to generation.
The hybrid that you bought from the dispensary has gone through months and even years of growing, crossing, and backcrossing, as well as a selection process to pick the best phenotype of that strain.
Breeding is about time and patience. Says Pennington: “To be a breeder, you have to be willing to accept the fact that you won’t have uniformity in the offspring, [you’ll get] lots of ugly ducklings in the hunt for your golden goose. To make seeds that will actually reflect the golden goose takes time, and it takes more than just a one-off cross. Even after you found your golden goose, expect to have to do a whole number of stabilizing backcrosses to reproduce your golden goose in seed form.”
How To Easily Breed Seeds And Create New Cannabis Strains
Maybe it’s not every growers ambition to start their own seed company – and nobody’s saying you should. Though it can be pretty cool to create your own cannabis strain. Just imagine you’d be the one creating the next Tangerine G13 or Amnesia Haze – or another legendary, award-winning weed variety.
Imagine you’d be the one creating the next Tangerine G13!
Creating own cannabis varieties is pretty easy too and could potentially be a green goldmine. Even if you don’t create the next Super Silver Haze on your first try, it is still worth trying. Cross-breeding your own weed strains is very educative and results in a huge collection of cannabis genetics. Meaning you might hold seeds to strains that are no longer being produced – to cultivate or cross-breed with.
Crossing Weed Strains
There is one thing you definitely need if you’re planning to breed your own weed strains: male cannabis plants. Unless your plan is to make feminized cannabis seeds, which is a different story we’ll dive into another time. To recognize and distinct male from female (and hermaphrodite) weed plants, have a look here.
Because although you can grow male cannabis plants in the same room as female cannabis plants. It’s important to separate the males before their flowers open, releasing their pollen into the room, to avoid uncontrolled fertilization.
Rest assured, there is no need for a separate grow room for the male plants to develop from there. As a flowering male can be held under a simple lightbulb or simply in the windowsill. Furthermore, you can even cut off a few branches and put them in a vase to collect the pollen a week later. Regular Cannabis seeds create male and/or female plants.
Selecting Parents For Your Strain
The trick to select the perfect male weed plant is to have good and above all trained senses. Because it’s up to you to see which male has the best growth and the most attractive (or present) aroma.
Hollow stems on male cannabis plants may indicate high THC-production in its offspring
Obviously, only select male cannabis plants with a nice structure and a healthy root system. If possible, cut off a few branches in search of hollow stems. As a hollow stem in weed plants is often an indicator for high THC-production in the plants.
Male plants that are quick to flower are often dominant in passing on their genes – so it’s best to leave those be. Late-bloomers however, carry recessive genes.
Crossing your female plant with late-blooming males will therefore retain the desired characteristics from your fem – instead of your cross turning into a copy of your male parent. If you’re serious about selecting the right male, make sure you have a separate room for them. As there you can leave them to flower longer, to discover more about their grow characteristics.
How To Collect Cannabis Pollen
Now you’ve selected the right male, it’s time to collect its pollen. A pretty easy job considering the plant is eager to release its pollen to fertilize female plants. Simply shake a branch with open male flowers above a sheet of (black) paper or a plastic container. And the pollen will fall down from the flower onto the desired surface.
Make sure there are no vents on and windows are closed though. As the male cannabis pollen is designed to travel with wind – and in this case we’re trying to contain it to not fertilize the wrong (or too many) female plants. Also avoid working with your female plants right after this job, as pollen easily sticks to your clothing and hair.
Fertilizing Female Weed Plants
Selecting the ideal female cannabis plant is easier than selecting males. As you can truly judge the fruits before you put in the labor. To guarantee a stable plant, try growing her out of seeds and cultivate it from clone too. Thereafter, you can choose the characteristics you like to see in your own creation(s). Be sure to take aroma, structure, flowering time, esthetics, taste and effect into account – as those are the most important elements to look for in a good cannabis plant. Logically, only select the best of the best females to create your own weed seeds with.
Simply use a paint brush to pollinate your female cannabis plant, with the collected male pollen. [Image: Gracie Malley / Cannabis Now]
Pollinating your female cannabis plants is as easy as collecting male pollen. Preferably wait until the plant(s) you want to fertilize are three to five weeks into their flowering period. Then take the selected female out of the grow room, again, to avoid uncontrolled pollination of the rest of the plants. Label one or more branches to fertilize, to know which plant was crossed with which and when. And use a clean (paint) brush to apply the pollen on one or more branches for seed production – leaving the rest of the flowers to produce seedless weed: sinsemilla.
Deactivating Cannabis Pollen
About three hours after fertilization, it is time to deactivate the leftover pollen on the plant. You can do that by simply spraying your plant with water. Be sure to change your clothes and have a shower after this, before you place the fertilized female back in the room.
After fertilization, you can let your cannabis plants fulfill their flowering period until they are ready to harvest. The seeds are fully grown after two to six weeks, but can stay in the bud and hung to dry after harvest. Your home grown cannabis seeds then require another month before they’re ready to be germinated – preferably with our favorite germination method.
Be sure to keep an eye on them once they start flowering, as you’ve now produced ‘regular cannabis seeds’. This means your plants can turn both male or female when they enter the flowering stage. Providing you with what you need to further stabilize your creation into the perfect weed strain.
What strain would you choose to cross your own variety with?
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The germination of cannabis seeds is illegal in most countries. Amsterdam Genetics cannabis seeds are exclusively sold as collectable souvenirs to customers living in countries where the cultivation of cannabis is illegal. All information on this website is intended for educational purposes only and is not meant to incentivize people to engage in illegal activities.