This article is sponsored by General Hydroponics, the leading innovator in the field of hydroponics for more than 35 years.
Cannabis propagation is a lengthy and complicated process that can take years to understand and decades to master. However, it doesn’t have to be, at least not for the home grower looking to get into breeding on a small scale. For some, breeding can be as simple as fortifying a small seed stock for next year’s crop, or even taking your favorite strain and keeping its pollen to cross with other desirable female genotypes or phenotypes in the future.
In this guide, we’ll review the basics of small-scale cannabis breeding techniques and illustrate the benefits these techniques may provide to those who want to create their very own unique cannabis seeds and strains.
Want to learn more about growing marijuana? Check out Leafly’s Growing Guide to get tips and advice from expert growers.
Why Breed Cannabis at Home?
What’s the big deal about breeding cannabis at home, anyway? For starters, breeding cannabis affords a home grower access to new hybrid genetics while also acting as a conservation mechanism to preserve (and even strengthen) desired genetics for future use. If you have distinct strains and want to create hybrids, breeding on this scale is both easy and effective.
On the other hand, those who wish to carry seed stock through to the next season will find breeding to be a sustainable alternative to keep those genetics around. Not every grower can afford to go back to the nursery or seed company and purchase new genetics between every season. After all, in most states the cost of a single clone can exceed $20, while a dozen cannabis seeds could easily cost $100 or more. For many micro-budget home growers, breeding is the only way to keep genetics around.
What Are the Limitations of Breeding for Home Growers?
Breeding cannabis at home does not come without its own setbacks and limitations. Medical and recreational growers in legal states must first comply with all their local ordinances pertaining to home cultivation. These include everything from plant counts to canopy limits and more. Breeding on this scale becomes a matter of adapting to these spatial and quantifiable limitations.
For instance, a popular breeding practice involves propagating genotypes in large batches (sometimes hundreds of plants in number) to see the widest margin of genetic variation possible. This allows growers to select only the most desirable phenotypes to cultivate further. However, when you have a maximum household plant count of 12, this isn’t possible. Home breeders must work around these issues if they wish to both breed and propagate sinsemilla cannabis (without seed) as well.
A Simple Propagation Technique for Small-Batch Breeding
If, despite the potential roadblocks, you’re looking to tackle some small-batch breeding at home, here’s a simple propagation technique you can follow.
What You’ll Need:
- One mature male cannabis plant, between 2-3 weeks into bloom phase (or collected male pollen)
- One mature female cannabis plant, between 2-3 weeks into bloom phase
- Isolated propagation chamber (e.g. a sealed grow tent or equivalent)
- Small paint brush
- Plastic baggies and ties
First, you must work within a clean and sanitized environment. Begin by cleaning your isolation chamber in preparation of receiving the female plant. A clean space will both help to prevent cross-contamination and provide a safe and sanitary place for the plant to fully mature. Diluting a small concentration of bleach or isopropyl alcohol with water should do the trick. Don’t forget to sanitize any pollination tools, like your paint brush, as well.
Make sure that your isolation chamber does not contain any female plants that you do not wish to breed with. This will ensure the prevention of unwanted cross-pollination. However, if more than one female cannabis plant must mature within the same space, implementing the following selective pollination technique (which involves using plastic baggies and some ties to protect the pollinated colas) should still adequately protect your room.
2. Collect Pollen
Male cannabis plants will begin to show their pollen sacs within the first week or two into their bloom phase. Shortly after, these sacs will open and pollen will become abundantly available. Once a desirable male plant has been identified, remove it from any female plants and isolate it immediately. The goal is to collect the staminate pollen without accidentally open-pollinating any other female plant.
Keep the desired male plant in isolation throughout the pollen collection process, then terminate the male to be safe. By using a small paintbrush, you can carefully collect pollen into a plastic bag or glass jar.
Keep in mind that pollen is “alive” and that humidity can dramatically affect the viability of the pollen. For storage, keep male pollen sealed in an airtight container and store in a cold, dark space such as a freezer for long-term holding. If you plan to access your pollen more than a few times per year, it’s generally better to keep it in a refrigerator because the temperature swing from storage to room temperature is much lower. Properly stored pollen may last for over a year under ideal conditions.
3. Selectively Propagate
A female cannabis plant in bloom is mature enough to receive pollen once flowers begin to form hair-like stigma. Without complicating this process too much, the object of selective pollination is to place male pollen onto specific branches or colas from which the breeder wishes to produce seeds. Each cola can produce hundreds of seeds if pollinated properly.
Choosing which/how many branches to pollinate will come down to grower/breeder preference. A single cannabis bud that has been pollinated can easily yield 20-30 mature seeds.
To complete this process:
- Make sure there is negative pressure in the isolation chamber before continuing.
- Prepare by collecting the baggie containing your male pollen, a paintbrush, and gloves.
- Gently collect a small amount of pollen from the collection baggie with your brush (a little goes a very, very long way).
- Run the brush gently across desired female flowers, making sure to only run the bristles across the tops of each stigma.
- Once a cola has been pollinated, you may seal the cola by covering it with a clean plastic baggie and tying it off to form an airtight seal (this will prevent cross-contamination). Note: this step is not necessary if (a) you intend to pollinate the entire plant in isolation, or (b) you do not have any issues with potentially finding a few seeds throughout the rest of your pollinated plant. (Pollen spreads easily, making this is a possibility.)
- To prevent any further contamination, keep your isolation chamber sealed throughout the maturation process.
This application process should repeat 1-3 times over the course of a week or two. After the fourth week of bloom, you may suspend your process. Should you need to reintroduce your pollenated female back into a room with other maturing female plants, you can rinse the plant down with clean water immediately following pollination to remove any excess pollen. This isn’t one hundred percent fail-proof, but when done carefully and correctly it can encourage the plant to breathe a little better.
4. Harvest and Collect Seeds
Your seeds should be fully mature once the plant has completed senescence. For ripe plants containing seed stock, it’s best to let the life cycle exacerbate fully before harvesting to give seeds their maximum time to mature.
After you harvest and dry your plants, it’s then time to collect seeds. Fully mature seeds are darker and often contain striped patterns covering their encasing. If executed correctly, you should yield a healthy quantity of seeds no matter how may colas you choose to pollinate. Congratulations, you’re now a certified home breeder!