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How to Sex Marijuana Plants

Marijuana Preflowering

Although generally considered one of the trickiest parts of growing your own marijuana, sexing is quite straightforward and will become easier as you gain more experience. The reason for sexing your plants is so that you can remove male plants before they have a chance to pollinate the females. If this occurs the females will start to develop seeds and this will divert their energy from THC production. Pollinated weed is still smokable, we’ve all had weed with seeds, but the potency will be significantly decreased.Careful observation of flowering is the only true way to sex your plants, although you may get a clue from their growth patterns. Male plants tend to be leggier than female plants with a longer internodal length. Female plants are squatter with more leaves and a bushier aspect.Towards the end of the summer, as the hours of daylight decrease, changing light levels will trigger your plants to produce flowers. The appearance of pre-flowers at branch junctions is what you are looking for.Male pre-flowers should be clearly visible to the eye, although a magnifying glass will make your job easier. Male flowers form at the junctions of the branches and stem and the pollen sacs form little balls.How to sex marijuana plantsFemale pre-flowers will also form at the junction of branches and stem and will normally start to form at the fourth or fifth branches up from the base. They are easily distinguished by the appearance of pairs of tiny white hairs, known as pistils.Marijuana PrefloweringAt this stage your plant is just about to enter the flowering phase of growth and now is the time to remove the males if you wish to.


As the plant enters the flowering stage its growth patterns and nutrient requirements will change. The vigorous vegetative growth will slow, stems will elongate and flower formation will begin rapidly at first before slowing. Your plant now needs less nitrogen but more potassium and phosphorous so now is a good time to add some ‘super bloom’ fertilizer. Follow the packet instructions for fruiting or flowering plants.FloweringThe female flowers will start to form kolas around the branch junctions with a main one at the growing tip of the plants. If you look closely you will see the seed pods and these will swell; either with seeds if your plant has been pollinated or with THC as false pods if you have removed the males.KolasAs the flowers become ready for harvest the pistils will darken and the seed pods will be swollen and sticky with resin and THC trichomes.Ready to harvestHowtoGrowMarijuana.com has a wealth of information for growers. We hope you now understand how to sex your marijuana plants. It might be worth reading some of the questions and answers made by our visitors below. 

125 thoughts on “How to Sex Marijuana Plants

  1. Allainyaha Charlene Matthews says:

    Good read, the article was what I was looking for

  2. Teddy says:

    Need to know if fish emulsion is a good fertilizer…?

    • Mike Collins says:

      Yes Alaska Bloom Fish Emulsion is the Best Organic Fertilizer there is and i know,this from successful experiences and excellent healthy strong well developed plants a a result.. there is virtually no reason to worry about the soil becoming to acidic or any chemicals in your weed..

  3. Randy says:

    Want to start a plant in January can I do this is the Seirra’s.

  4. Ingrid says:

    I am also growing to learn seriously for the first time. My baby started it’s life from seed and then spent the whole summer outside (this is Anchorage, Alaska) summer time is approximately three months in duration. It was out there in 30-50 mph winds and rain storms, with roughly 20-23 hrs of daylight. By the time we brought it indoors it was nearly 6′ tall but strong as all get out. The only water it got was rain water. Right now we have it and another plant on 12/12. The other plant which is squat and bushy w/ a lot of branches, has been closer to the light source because we are one light shy, so there is one at the top and a light on just one side of the room in which the above mentioned squat plant resides. We have some indication that the previously outside plant is hermaphrodite also the swat one is of course flowering more rapidly. Is there anyway to keep your plant from turning? Because if not, we do not have two separate spaces for flowering them apart so we will have to destroy it so it does not change the other one. I know, long winded but bare with me. How can you tell if your plant is Indica or setiva and so on?

    • Buddy says:

      Tall and thin = sativa. Short and bushy = indica. ALthough most plants nowadays are actually hybrids.
      If you keep the hermie plant with the other plant then it will pollinate it. You have 2 choices. Either bin the hermie, or smoke weed with seeds. Up to you. If you can see the hermie flowers then your plants are already in flower.

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