5 Tips on How to Sex Marijuana Plants

Sexing a marijuana plant is really just finding out whether they are male or female. This is very important information for two reasons. The first is that female plants are the only marijuana plants that will produce the buds growers are looking for; males are reserved solely for fertilization and creating seeds. The second reason it’s important to know the sex of every marijuana plant because if males are left with females when their pollen sacs are ready to burst open, they will pollinate the females and the growers will be left with only seed.

How to tell if your plant is male or female before flowering

It’s very easy to identify plant gender once plants have matured and have started to show their reproductive organs. But truthfully, waiting until this point is risky. If the males and females are in the same room, the males could pollinate an entire crop at any moment, and even moving them could cause those pollen sacs to split and fertilize any females nearby. Instead, growers are better off looking for signs of sex before the plants begin flowering.

Male plants grown outdoors will exhibit different growth signs than their female counterparts, and this can be a good way to identify males and females. The vegetative stage is the first stage of growth for marijuana plants. This is the time when they get bigger and rounder, and are
simply focused on growth. While their reproductive organs won’t yet be present, growers can keep a keen eye out for growth patterns that could be an indication of sex.

During this time, females are known to have more complex branching systems, making them seem rather “filled out”, and widening as the branches continue to grow. Male plants on the other hand, are spindlier and typically focus on growing taller rather than wider. Male plants are often not as filled out, with fewer branches and fewer leaves on them.

Male Marijuana pollen sacksThese signs are typically displayed only when plants are grown outdoors. These signs are no indication that the plant needs to be removed from the crop, but they can give growers a good idea of what plants to keep an eye on.

Male plants will also mature about two weeks earlier than female plants, regardless of whether they’re grown indoors or out. About two weeks before they fully mature, male plants will grow what are known as “false buds”, sacs that resemble buds, but are actually sacs of little, white flowers. Female plants do not have these white flowers, as they release the pollen which is to then pollinate the females.

It’s for this reason that
male plants will grow to be so significantly taller than the females, so that when the sacs break open, the pollen can scatter onto the females. This sudden growth, near the end of the vegetative stage, is the best way to determine the sex of marijuana plants before they actually flower.

Sexing a marijuana plant

Trying to identify a plant’s sex by height and volume alone is not fail-proof, but there is a way to determine a plant’s gender before it matures that works every single time – cloning.

Cloning is a simple process of taking a cutting from a plant and placing it in a growing medium so that a whole new plant grows. Because the new plant is a clone, it will be identical to the plant it was taken from, including its gender.

Cloning plants to determine gender is fairly straightforward when there’s only one plant in question, but when there’s an entire crop it can become a bit more complicated. It’s important to identify which clones came from which plants, so growers know which plants are male and need to be removed from the female plants.

Of course, it does no good to simply clone plants and have them grow at the same rate, as they will show signs of their sex at the same time, or even a bit later, than the original plants. To expedite the process, growers must force the clones into the flowering stage by using a light cycle of 12 hours of light followed by 12 hours of complete darkness. Because sexing clones depends on this light cycle, it cannot be done with auto-flowering plants.

Female marijuana plant

Female Calyx on Marijuana Female Calyx, not to be confused with a pollen sack

While male marijuana plants have sacs, or false buds, female plants have what many refer to as “white hairs”. These hairs are actually pistils, and they’re quite sticky so that they can catch the pollen the male plants release. When this happens, the female plant will then be fertilized and will produce seed instead of the beautiful tightly-packed buds most growers are looking for. For this reason, male plants should be removed from the female plants before either begins to show signs of sacs or pistils.

What to do with male marijuana plants

It is important to identify male plants, and to remove them as far as possible from the female plants. This is because the pollen from males is known to be undaunted in its quest to fertilize female plants, going so far as to travel through ventilation systems and traveling fairly long distances in order to do it.

For this reason, in the past many growers chose to completely destroy male marijuana plants, so there was no chance they could fertilize the females. However, this isn’t actually necessary and growers who do so could be hurting themselves, as male marijuana plants have more uses that might meet the eye.

The most obvious reason for keeping male marijuana plants is that they are necessary for breeding. Once growers become more experienced and familiar with the process of growing, they often want to move on to breeding so they can create their very own strain. Just like in other parts of nature, in order to create a new genetic line, both males and females are needed and a strong male plant will help produce a strong line.

Perhaps a less obvious reason to keep male plants around is that they can be great for the garden. It’s been reported that for centuries farmers around the world have used male marijuana plants in their gardens for the terpenes they produce. These terpenes deter pests from invading vegetable crops, and when the leaves and flowers are dried, they can actually be sprayed onto other plants as a pest deterrent. Of course, male plants should never be used to deter pests, mould and other nuisances from female plants, as they would be too close to them, but they can be used effectively with other crops.

The stalks of male plants are also finer, yet stronger, than female plants, and this is useful when making hemp products. Because the fibers are finer, they produce softer material that can be used for clothing and linens. In Hungary, male marijuana plants are revered for their fibrous stalks.

Lastly, while it’s true that male marijuana plants will not produce buds, this doesn’t mean that they don’t contain any THC, as it was once believed. In fact, while male flowers will have significantly less THC than female flowers, the leaves of male plants have more THC than a female’s leaves.

How to sex seeds

For growers that don’t want to spend the time cloning plants or searching for signs of height, there is a way growers have found to identify sex just from the seeds. While it’s not a scientific method and results are not 100 percent guaranteed, growers who have tried it have reported a success rate of 90 percent.

Sexing seeds is done during the germination stage, when the seed just begins to sprout. It’s thought that if the seed sprouts at the top or the bottom of the seed, the plant is likely a female. Sprouting Marijuana SeedsHowever, if the sprout appears at the side of the seed, the plant is most likely male. Again, this isn’t a way to determine a plant’s sex exactly, but it does again, give growers an idea of what plants need a special eye kept on them.

Sexing marijuana can be a longer process than many growers are hoping for, but it’s an important part of the job. When growers are looking for beautiful, potent buds, male and female plants simply cannot be grown near each other, so they need to be identified as early as possible. There are many ways to do it and as growers become more familiar with the process, they will understand which one is easiest and works best for them.

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