Determining the Gender of your Marijuana Plants

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One of the most desirable occurrences for a marijuana grower is to have only female flowers which are unfertilized. This is because, they have huge contents of THC during harvest. This is where marijuana sexing comes in. It is simply the process of determining the gender of the plants and separating them. It is quite a tricky process but with time, one gains experience and can comfortably sex the marijuana plants. Keen observation is key in knowing the sex of your plants. In this article, we will focus on the tips and methods that you can use to correctly determine your plants’ sex.

Checking Pre-flowers

Pre-flowers are small versions of adult flowers that usually appear in our plants at the vegetative stage. You will find some growers saying that you cannot determine the sex of your marijuana plants till they start flowering. That is not true. Pre-flowers grow 3-4 weeks after germination for male plants while for the females, they grow from the 4th to 6th week. Pre-flowers are found where the stem meets the main stalk, usually near the top of the plant. Male pre-flowers will tend to have a spade-like shape.

Female pre-flowers are longer than the male ones. They also have 1-2 pistils that manifest themselves as white hairs and stick out of the top. Sometimes the pistils will not appear and you will need to check the shape of the pre-flowers carefully.

Chemical Leaf Tests

This can be used for your plants which are as young as 1-3 weeks to determine the gender of your marijuana plants. The chemical test can also determine the future cannabinoid ratios of your plants. This test used to be very expensive but is getting more affordable with time.

Only a tiny tissue of the plant tissue will be required. A real-time polymerase chain reaction test (qPCR) is used to determine the gender. High-Pressure Liquid chromatography with a Diode Ray Detector (HPLC) is used for potency tests. Chemical tests can be conducted on the plants from the first week after germination, but it is advisable to wait till the third week so as to get accurate results.


This can be a perfect way to determine the sex of the marijuana plants before they attain maturity. You will have to take cuttings from a number of your plants. Put the cuttings into containers with soil. Let them grow for a number of days, then induce flowering. This is done by exposing them to 12 hours of light and 12 hours of darkness. The clones will enter the flowering stage and hence determination of both the clones and the hosts’ sex will be easy.

In males, the pollen sacs formed before flowering will open up to form small white flowers. Females won’t have any of these and will instead have hairy, whitish pistils. The pistils will be waiting for pollen from the male flowers. This method of determining the sex of the marijuana plants is time-consuming and is not recommended.

Sprouting spots

This is a risky method of determining gender. It has not been documented by researchers. Experienced growers have however stated a 90% success rate in predicting the gender using this method. During germination, if the sprout comes from the side, it will turn out to be a male. If sprouts come from the top or bottom of the seeds, they will turn out to be females. It would be advisable to use this method in combination with another.

Maturity rate and growth structures

During the vegetative stage, you will notice distinct differences between the plants. Males will tend to be taller, with fewer branches. The males are taller to enable pollen fall on the female’s reproductive organs. They will also mature at a faster rate. You will notice early false ‘buds’ on them. These are pollen sacs.

Female plants will have more complex branches and will look more solid. They will also be slow in maturing. This method is also not very accurate and one should not rush into uprooting some plants without further proof.


Adapting the right methods of sex determination in marijuana plants is therefore very important. It ensures accuracy and good harvest at the end of the day.