Breeding Cannabis and What To Know

01 Nov 2021

We are living in a time now where there are more seed banks than ever before, with each offering their own stable lines, or are doing their best to keep up with the latest trend. All breeders have to start somewhere and there is no better place than the comfort of your own home. In this article we break down all you need to know about breeding Cannabis plants , what to look for during the selection process, desired traits, sexing plants, and much more.

Set Your Goal

The very best way to ensure a successful breeding project is to plan ahead. This means that before you have even purchased the seeds in mind, you already have a solid plan on paper at least that will validate the upcoming work. Most overzealous breeders will already be choosing a name before having a goal. Below are some examples of what traits you may want to consider before you germinate a seed.

  • The flowering time
  • Production / yield
  • Structure of the buds
  • Height
  • Growth structure
  • Trichome production
  • Resistance to stress
  • Resistance to pathogens
  • Cloning ability
  • Potency
  • Flavour

You will need to start with regular seeds which means the Cannabis plants that will grow, shall be either male or female plants. Next you will need a designated space where the male and females will be kept until the pollination has been successful and you can ensure there will be no risk of cross contaminating any other plants you may have through the air vents.


Male flowers are now mature and ready to pollinate the female.
Male flowers are now mature and ready to pollinate the female.

A Good Starting Point

It is a good idea to start with 10 regular seeds of one strain and 10 regular seeds of another. The pot size you use can be between 6.5 litre to 10 litre. Even though you will start with 20 potential candidates, once flowering begins the final count of keeper males and females will be minimal. 

Label Everything!

One great habit to form if you are an aspiring breeder is to label everything you work with. The details of the label at first will be very basic for example ‘ Rainbow Belts 1-10 ‘ and ‘ Neville’s Haze 1-10’. Over time as you learn more about the plant's height, aroma and esters from stem rubbing, structure, leaf pattern, and how well they root, you can begin to write notes on the labels or a separate note pad which can be referred to at a later date as a way of capturing all the data. Labeling does not take much time or expense and is one way to remain organized and focused, especially when taking cuttings later on.

An example of how a label on the pots may read is ‘ Neville’s Haze #4 - Fast root, musky smell, tall pheno ‘. All of these small notes will play a massive role when working back through the Cannabis plants and narrowing down which desired traits and phenotypes you want to move forward with. 

Identifying Male and Female Plants

This is the part that some growers can find overwhelming and one reason why they always work with feminized seeds, or reputable clones. The reality is male plants will reveal themselves sooner than females, as naturally they require a head start to ensure synchronicity with the female plants when flowering. 

By this point, you will most likely have your eye on a few plants that stand out, and these are the ones you will be praying are either male or female. Female Cannabis plants will only produce small white fuzzy hairs between the internodes and axillary shoots. 

  • Male flowers will be round shaped and look like small green pods.
  • Female pre-flowers are small and thin white hairs around 1cm in height.
  • Male Cannabis plants can typically show their pre-flowers earlier than females.
  • Pre-flowers will emerge after the first two weeks of 12/12.
  • Male pollen will take 3-4 weeks before releasing itself so there is plenty of time. 

How To Pick The Best Male

There is no set formula on how to pick the best males, however there are a few different things you may be able to pair the plants up together. Generally a male Cannabis plant that has the same structure, growth pattern and height as a female will typically pair up much better and produce more stable and uniform progeny. 

On the other hand, some males are what is called non-dominant and will not express themselves too much when working with the first-generation cross. This is where the art of selection and having a long term goal come in handy, as over time you will learn which of the Cannabis plants in your garden share similar traits and pair off better. 


A seeded female plant that is now 4 weeks into 12/12.
A seeded female plant that is now 4 weeks into 12/12.

The Pollination Window

Once you have passed the first 14 days of flowering, your Cannabis plants should have revealed which sex they are, and hopefully the ones that you had your eye on from the beginning are in fact male or female. It is advised to work exclusively with one male plant to keep the project as simple as possible and to avoid any cross contamination from other pollen. 

The male pods will begin to turn from green to a light yellow colour that ends up opening up, like an umbrella. At this point you will see what looks like a bunch of tiny bananas hanging off a small stem. The slightest vibration can cause the pollen to disperse through the air and to drift off with the wind, so be very careful not to unintentionally flick pollen and its best to not have any fans on. There are a couple of different ways to pollinate female Cannabis plants and these are covered below. 

  1. Using your finger and thumb and gently hand pollinating the female pistils with the male pollen sac. You will feel a smooth coat of powder on the tips of your fingers meaning the pollen is perfect to use. You can also wait a week more and then cut the pollen sacs off into brown paper and then use a small paint brush to apply the pollen directly onto the parts of the female you want to produce seeds. 
  2. The male Cannabis plant can be paired closely to the females and then shaken to encourage it to produce a large pollen cloud. This method is much more careless than doing by hand and will ensure an entire plant is pollinated from top to bottom. It may be a good idea to perform this technique twice after the third week of 12/12.

When Are The Seeds Ready To Pick?

The harvest window will be the same as if you were flowering the Cannabis plants normally, the only difference is the plants are now focusing their energy on producing seeds. When you take a closer inspection at your seeded plants, you will notice they have pointy characteristics with an oval shape. It won’t be possible to see how mature the seed has become as it can be hidden within the calyx, until the seed is ready to burst out. Of course you can always pick a seed off the plant as you get closer to the harvest window, to give yourself an idea of how far off the seeds are. 

  • Avoid seeds that are green, white, or pale grey as these will be immature.
  • Seeds that are darker in colour and have a pattern on the shell are best
  • You should be able to squeeze the seed and it resembles a solid press. 
  • The patterns on the Cannabis seeds can change with maturity. 

Storing Your Seeds

Now all of the hard work is done and you are ready to harvest your dry plants and shake those seeds off. Give the seeds a cleaning with air and shake them around in a cup to remove any tiny pieces of organic matter that may be attached. 

You will want to store the seeds in a temperature-controlled environment such as a cool and dark cupboard, or the most consistent being a fridge. Label your packs correctly based on the original labels and notes that were made, so when working through the line or in future case scenarios you have all the details you need. 

An example would be ‘ Neville’s Haze #9 male x Rainbow Belts #3 female ( Fast flowering female, fruity terps, heavy resin, medium height plants.)


Breeding Cannabis and What To Know

The Final Conclusion:

Breeding Cannabis plants can be accidental sometimes, then again you can really take your work and research to a whole other level. It all depends on your goals and ambitions, so good luck producing your own hybrids in the comfort of your home and hopefully finding that next big thing!