Male vs. Female Marijuana Plants

The primary difference between male and female marijuana plants is the fact that females grow buds, while male plants do not. Generally speaking, a typical marijuana seed is going to have a 50% chance of being either male or female. That means that, if you buy 20 seeds, only about 10 of them will actually be producing the buds that you want. For this reason, knowing the differences between marijuana plants’ sexes is imperative. In this article, we will cover exactly how to tell the difference between a male and a female marijuana plant.


When Can You Tell Which Are Male And Which Are Female?

As you probably already know, marijuana plants first go through their vegetative stage, followed by a flowering stage. The vegetative stage is kind of like the childhood of your marijuana plants, as the only thing they are doing is growing as big and strong as possible. Nothing else matters during the vegetation stage, including gender.

That being said, there is a sort of mini stage when you might be able to tell which plants are male and female. This is because they start having “preflowers.” This generally occurs about 6 weeks after the plants have been in their vegetative phase. The preflowers can be used to determine which plants are which gender even before the flowering stage has begun -- and that can be an incredibly handy tool.

If your male plants are allowed to grow and mature alongside your females, you are going to end up with pollinated female marijuana plants. This is the opposite of what marijuana growers want, as these pollinated females will then put their valuable resources to work growing seeds rather than increasing the size and potency of their buds. For that reason, identifying and removing male marijuana plants is extremely helpful in improving your crop.

After the vegetative stage, the flowering phase occurs. This is when your marijuana plants won’t grow big and tall any longer, but rather will use their resources to grow flowers (also known as the buds we are looking for). This stage can be thought of as the adult stage in a marijuana plant’s life. They will be growing their male and female flowers as much as possible, and then will do their best to pollinate and produce seeds. Female flowers are, of course, the only thing that we marijuana growers want, so the male plants are essentially useless at this point (and can create a big hindrance for growers as well).


Revealing Gender With Preflowers

Depending on the strain you are growing (and sometimes the individual plant itself), your plants might develop preflowers that can show you which genders they are going to be. The female plants will start growing pistils, while the male plants will start developing little balls. These pistils and balls should show up when your plants are around six weeks old.

It can be difficult to tell which preflowers are which sometimes, but if you wait a bit longer, it should become clearer. The little balls that male marijuana plants begin developing as preflowers are actually the beginning stages of pollen sacs. If this pollen is released, it can mean devastating consequences for your female marijuana plants.


Identifying Sex During The Flowering Phase

If preflowers never developed, do not fear: all is not lost! You simply need to be ready to identify your male plants as soon as possible so they can be removed from your crop immediately. The key is to get all of the marijuana plants out of your crop, but not accidentally remove any of the female plants, as that would be a hugely unfortunate waste.

Luckily, the male plants will start revealing themselves about two weeks before female plants do (on average). That should buy you some time to remove them. They will also grow to be a bit taller than female plants, as that allows their pollen to better sprinkle onto the female plants around them. Their pollen sacs will resemble grapes in their cluster and shape, and they will grow larger and larger until they crack open and release their pollen. The preflowers are far smaller and sometimes tricky to see, so you will have to look closely at the nodes to spot them. Be careful, as sometimes preflowering females have growths that resemble immature pollen sacs -- when you’re not sure, it’s best to wait for a while.

Female plants can be identified with the white, thin hairs (or even just one hair) that grow where the buds will form. You can check for them along the main stem where its smaller branches are growing from. If you kept your plants in their vegetative stage for long enough, you might even discover these hairs before the flowering phase has begun. As soon as you see this white hair, you can know for a fact that the plant is a female.


Cloning To Identify Sex

One technique that many marijuana growers use to find out whether their plants are male or female quickly is cloning. When your plants are young, there is nothing you can do to see if they will be male or female plants. Many growers would like to identify the male plants as soon as possible so they can remove them immediately and not waste any more time and effort on plants that are unusable anyway. If you fall into that category, the cloning technique is for you.

You will need to take a cutting from the marijuana plant in question (or all of them, as long as you keep everything perfectly labeled), then grow it as a clone somewhere else. Be sure both the mother plant and its clone are labeled so you know which ones go with which -- otherwise, your efforts will be completely useless.

As soon as your clones have grown their root systems, you can begin flowering them (far earlier than you would usually want to flower a marijuana plant). Do this in the standard way, with 12 hours of sunlight and 12 hours of uninterrupted darkness. Be sure your clones and mother plants are kept apart, as they will have completely different lighting schedules.

After a week or two of this 12/12 lighting schedule, the clones should begin developing flowers. You will be able to tell which are males (by their balls) and which are females (by their white hairs). Once you know which is which, you will know exactly which of the mother plants are male. Remove them and discard them.


Lighting And The Vegetative And Flowering Stages

If you are growing your marijuana plants indoors, then lighting is a highly important part of your growing process. More than anything, the timing of your lighting will make a huge difference in how your plants grow in their various stages, and when they switch from the vegetative stage to the flowering phase.

If your plants are kept on an 18 hours on, 6 hours off schedule per day, they will remain in their vegetative stage. The same goes for 24 hours on, and 0 hours off (just continuous light). Generally speaking, you don’t want to give your plants less than 18 hours of light per day while they are growing vegetatively. When you switch the lighting schedule to 12 hours on and 12 hours off, however, your plants will go over the flowering phase and start growing buds.

The 12 hours of darkness is actually far more important than the 12 hours of light when it comes to transitioning your plants into the flowering phase. If there is even the briefest moment of light (any kind of light) in the middle of the “nighttime” hours, your plants will reverse back to the vegetative stage. Be absolutely sure that they have proper darkness during this time.

This has to do with how marijuana plants would grow in the wild. It also has to do with the changing of the seasons. As the seasons get closer to the autumn and winter months, the daylight hours begin to shorten and marijuana plants “know” that they will need to start flowering soon or else winter will come before they are able to. The key is to reproduce before wintertime, so this light acts as a signal for it to begin flowering. If you are growing indoors, your change to the 12/12 cycle “tricks” your plants into thinking winter is coming, no matter what season it actually is.

If you are growing outdoors, you won’t need to worry about this at all. The only thing you will have to think about is whether any sources of light are hitting your growing area. For example, is there a streetlight that has some light reaching your plants? If so, they won’t be able to have the necessary uninterrupted darkness to begin flowering, and more extreme measures may be required.

If you are growing indoors, you should invest in a timer for your lights. The 12/12 transition works best if the change from light to dark and dark to light occurs at exactly the same time every day. Because human error is inevitable and something could get in the way of you doing it yourself, a timer will simplify everything.


Autoflowering Strains Of Marijuana

While almost all strains of marijuana have traditionally been photoperiod-dependent strains (meaning they depend on the light changes to begin flowering), nowadays autoflowering strains of marijuana are also relatively easy to come by, especially if you are buying from marijuana seed banks. These strains don’t need any light changes at all and instead begin their flowering phase based on time rather than light.

If you want to grow more than one crop of outdoor marijuana in a growing season, autoflowering marijuana seeds make the most sense (as your first harvest would be in the middle of summer, when the light is at its peak). It also makes sense for many indoor growers.