How to Sex Marijuana Plants

How to Sex Marijuana Plants

An important aspect of growing… ditching the guys, wining and dining the ladies. Let’s learn how to sex marijuana plants!

Did you know there are both male and female marijuana plants? Yes, marijuana plants show gender, and the sex matters a lot to the grower. Although generally considered one of the trickiest parts of growing marijuana, sexing is quite straightforward and will become easier as you gain more experience.

How to Sex Marijuana Plants

In this article we’ll go over why and how to sex marijuana plants to provide the best possible buds. Have a question we didn’t cover? Visit our Newbie Central forum to get your questions answered.

Why is sexing marijuana plants important?

Sexing is an important part of the growing of marijuana. It is the source of much needless worry for beginning growers. You want to sex your plants to remove males. Male plants have low potency. Those interested in the psychoactive effects will want to cultivate the females for their flowers.

Male plants are generally only interesting to breeders who wish to collect and use their pollen in crossbreeding (hybridization) projects. In the 1960s people used the leaves, stems, and fertilized flowers effectively medicinally with excellent results. The leaves or “shake” can be smoked with relatively good results. However, the flowers are the most potent especially when not allowed to be fertilized.

Cannabis plants, when grown from regular (non-feminized) seeds, will generally germinate in a 50-50 male-to-female ratio, so in a pack of 10 seeds, expect to get five females.

When can you sex marijuana plants?

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.

How do you sex marijuana plants?

Determining the sex takes a subtle attention to detail and quick action. Below are a few tips for sexing marijuana plants.

  1. Look at the growth patterns.

    During vegetative growth, every plant, regardless of sex, will start to flourish. As the plants age, however, you will begin to notice subtle differences in their sizes. Some marijuana growers have even noticed certain signs early on that can help you determine the sex. Females tend to have more complex branching when they progress from the seedling stage to the vegetative stage. Males, on the other hand, tend to be slightly taller and less filled out. Of course, the last thing you want to do is pull plants out at this early stage, but this can help you get an idea so you know which plants to watch later on. (Note: marijuana plants grown indoors under artificial light don’t usually exhibit these tendencies).

  2. Males mature faster than females.

    This is one of the most common ways to determine sex on sight. Males will generally reach sexual maturity about two weeks before females. The males will start to grow rapidly and they will be taller than their female counterparts. They will also have these “false buds” which are actually pollen sacs. The reason the males grow taller is so that the pollen can drop down on to the female reproductive organs. This occurs whether you’re growing marijuana indoors or outdoors.

  3. Males have flowers, females have pistils.

    Obviously, all marijuana plants have flowers at some point, but, if you can’t differentiate between male and female just by height, then flowers and pistils are good indications of sex. Those false-bud, pollen sacs will eventually open up to form little yellow or white flowers. Any female plants will not have these. Instead, they will have hairy, whitish pistils that will be sticky enough to trap the pollen dropped from those flowers. If you wait this long to identify the sex of your marijuana plants, then it’s probably too late to get any sinsemilla buds. Even so, you can still remove the male plants to make room for the continued growth and cultivation of the female plants.

Male Marijuana Characteristics

Sexing Male Plants
Left: Early signs of male cannabis flowers. Right: Well developed male cannabis flowers.

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. They kind of resemble balls hanging from a slender stem. The pre-flowers buds are about the shape of a rugby ball and blunted at the end. When the male flowers begin to mature, they transition from hanging to a more erect position on their stem. When the flowers open, they reveal five yellow or white petals and a central stamen that releases pollen into the breeze.

Once a male plant shows a pre-flower, it will be less than two weeks before it begins openly pollinating, so upon sexing a plant males should be immediately removed.

Female Marijuana Characteristics

Sexing Female Plants
Clear signs of a female are the long slender stigmas that range in color from white to pink or lavender.

Female cannabis flowers are identified by the presence of their pistils. They have no flower petals like those of the males, but instead produce two long slender stigmas that range in color from white to pink or lavender. These stigmas collect pollen released into the air by the males, and then deliver it internally to the ovaries which pollinate the egg and produce the embryo. Once the stigma has done its job, the embryo begins to grow into a seed. The stigma is no longer needed and dry up within a few days. The ovary at the base of the pistils begins to grow as it produces a seed.

Hermaphrodite Marijuana Characteristics

Sexing Hermaphrodite Plants
Hermaphrodite’s have both sex organs.

Cannabis plants are fundamentally either male or female, however both have the ability to turn hermaphroditic. This means that a female cannabis plant can grow male sex organs and produce pollen and that male plants can grow female pistils. Hermaphroditic male plants are of little concern because males are generally removed from the garden. On the other hand, female plants that grow male sex organs can pollinate themselves and other nearby female plants. The female plants can then produce seeds which degrades the quality of the harvestable cannabis. Hermaphroditism can be triggered by plant stress, chemical treatments, erratic light cycles, or by genetic predisposition. Seeds created by hermaphrodite pollination should be discarded as they are more likely to pass on this trait.

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.

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