How To Sex Cannabis Plants

How To Sex Cannabis Plants

Sexing cannabis plants, determining the males from the females, can be a tricky endeavour. Unfortunately, for most growers, it is a necessary part of growing. This is primarily an issue for those who don’t want their females to be fertilised by accident, or at all as the case may be. Even for those who do want to breed their seeds, it is important to separate the males from the females to avoid accidental babies. Males aren’t enormously useful for harvesting as their buds and THC are non-existent. Ensuring the males and females are separated needs to happen quickly and can be tricky. There are quite a few things to look for that will help us spot the males amongst the females.

Female and Male Anatomy

One of the primary ways to separate the male and the female plants is the same as with most creatures, have a look at their organs. Male and female plants produce different sex organs as they mature to mate successfully. Both plants will produce flowers as they grow, but the males will simply grow flowers and females will grow pistils. Males grow a sort of false bud that is a pollen sack but can be hard to tell from a maturing bud. These buds will open and turn into little white and yellow flowers ready to spread pollen. The females won’t grow these flowers they will instead create pistils that are there to take on the pollen of the male. When we identify the males we can move them to a separate growing area or destroy them to give the females more room to grow.

Growth Patterns

We can catch males a little earlier on if we carefully watch their growth. Once they have gone through the essentially identical seedling stage they will show a difference in growth rate and style. Females tend to produce a higher number of branches as they go through vegetation, where the males tend to be taller and a little more gangly. This is one of the signs of gender, but for anyone who isn’t sure don’t start ripping plants up.

We can also tell the males from the females because they mature faster. Males, as they get through the vegetative stage, will start to flourish and will grow very quickly. They will start to produce their fake buds about two weeks before the females produce their real ones. So any taller plants, producing buds and looking further ahead in their maturity will likely be males.


For those who have a keener eye and a bit more experience it is sometimes possible to catch the difference in genders right at the start of growing. Some growers have been able to tell as early as post-germination. It is thought that when the sprout emerges from the top or bottom of the seed the plant will be female. This means that any seeds that sprout from the side of the plant are male. This proof for this is purely anecdotal so anyone unsure about sexing plants may want to wait until they see clearer signs. This might be something we can attempt later on after monitoring our sprouting seeds for a few crops.

Chemical Testing

For anyone who is still a little sheepish about simply telling by looking at the plants, there are more definitive methods. A chemical leaf testing kit is easy to buy online and can be used as early as week 2. The test just pops a little section out of the leaf and so won’t do too much damage to the plant. These test will identify chemically whether the plant is male or female using a range of DNA based tests. This is the easiest way to find the difference between males and females, but also the priciest.


Hermaphroditic plants can be an issue for new growers because they show signs of being both male and female. These mixed signals can make life a little tricky for growers as we don’t want to accidentally throw away any productive female plants. Hermaphrodites can appear due to stress or environmental issues so as long as we are careful we shouldn’t come across too many of these. If we find any of these plants they are definitely still fine to keep, we just need to make sure we snip off the male pollen sacks or flowers before the plant self pollinates or pollinates any other females in the crop.

Altering the Ratio

There are ways that growers can improve their chances of growing female plants. What causes plants to be a certain sex is still a mystery, but there are ways to increase the likelihood of a seed growing into a female plant. Obviously, the easiest way to do this is to simply purchase feminised seeds. However, for those who just want a higher ratio of females, there are environmental considerations to take into account. Playing with heat, light and stressing can alter the gender of a seedling, causing stress is likely to produce male plants. If we want more females we need to try and ensure that these factors are kept at steady levels. Avoiding excessive heat, high humidity, long days, harsh light, nutrient deficiencies and unhappy roots are all good ways to improve the chances of a female plant. Growers have until week three to try and convince the plant to be female, after that they will have set their sex permanently.


The last way to check the sex of a plant is to use a cutting to create a clone. Planting a clone of a plant and then forcing it through the flowering cycle will tell us the sex of the original plant. We need to separate the clone plant and push it with a 12 hour light and 12 hour dark period. As it flowers we can see which gender it is and, since it is genetically identical to the original plant, we can tell if it is female or male.

Remember: It is illegal to germinate cannabis seeds in many countries including the UK. It is our duty to inform you of this fact and to urge you to obey all of your local laws to the letter. The Vault only ever sells or sends out seeds for souvenir, collection or novelty purposes.

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