Last year, with the help of the cannabis community at large, we introduced Breedbay's "Ultimate Newbie's Guide". Filled with fantastic, fast-hitting grow tips, the "Ultimate Newbie's Guide" became the first in what is to become a series of Breedbay "Ultimate" grow guides to come. Now we are announcing the second addition in this series, the "Ultimate Plant Sexing Guide".

Over the last few months, we have seen more and more posts from "newbie" growers asking how to identify the sex of their plants. The topic of sexing plants for all new growers can certainly be a confusing and intimidating subject. Information on this topic is sketchy at best. Usually, you'll just find a pic of a female and a pic of a male and a good luck wish, that's it. The "Ultimate Plant Sexing Guide" is so much more than that! In this guide, we will take an indepth, upclose look at male and female plants as well as dive into the reproductive process of Cannabis.

It is our hope that this guide will serve to remove most if not all the mystery surrounding the sexing of cannabis plants and also serve as a reference for all to come back to time and time again. Enjoy the read!


When compared to most plants on Earth, Cannabis plants are quite unusual but not unique in respect to the fact that there are seperate male and female plants within the species. They are Dioecious plants. Meaning that the male and female sexes are expressed in seperate plants. The largest percentage of fruit or flower bearing plants contain both sexes in the same plant. Therefore, they self-pollenate with the assistance of insects carrying the pollen to the female pistillate (ie, tomatoes, peppers, flowers, etc.). There are anomolies within the genus of Cannabis plants, called Hermaphrodites, that also contain both the male and the female organ but we'll address this more indepth in a moment.

Outdoors in nature, female Cannabis plants are pollenated by male pollen carried by the wind. Most all other plants are pollenated by insects that are drawn to plants by brightly colored flowers. Not the case with Cannabis. Upon release of the pollen by the male plants, the wind can spread the pollen for miles. One male can produce enough pollen to pollenate thousands of female plants within several hundred feet of the male's proximity.

Why is it important to know the sex of my plants?

Good question! Male plants, while crucial in the natural reproductive process, are only useful in breeding Cannabis plants (by harvesting pollen from choice, select male plants) and for it's fiber. On the other hand, female plants produce the euphoria enducing THC resins (Delta 9 Tetrahydracanabinol) sought after by Cannabis enthusiasts and for medical patients seeking it's pain-killing and healing properties.

Unpollenated females will produce prolific amounts of flowers that form into elongated spears known as "colas" that contain copious amounts of the aforementioned THC cannabinoids. These unpollnated females are known as Sensimilla (pronouned "Sin-Se-Mee-Ya", a spanish term meaning "seedless" or without seed) and are the most potent, desired and valued form of Cannabis. If allowed to remain unpollenated for their entire life cycle, these plants are able to focus their growth hormones and energies toward the production of female Pistillate (the female organ) and toward the production of trichome glands (which contain the THC layden resins). Once pollenated, the female plant focuses it's energies on producing seed. Therefore, the yield of consummable cannabis is signficantly decreased in a pollenated female and the potency is lessened by comparison. By culling the males from your garden prior to pollenation, the resulting females will blossom into the highly coveted Sensimilla.

To fully understand the process of sexing your plants, we must first look into how cannabis sexually matures and procreates.

The Reproductive Process

Just like all annual fruit bearing plants, Cannabis plants are genetically programmed to reproduce to carry on it's own genetic lineage through it's off-spring, the seed. This dire need to reproduce can be seen in some strains of female plants that late in flower will, even in the absence of male pollen, produce it's own male preflowers in a desperate attempt at self-pollenation to continue it's lineage. These plants are not deemed Hermaphoditic (possesing both male and female sexuality) but do show that a plant will go to all measures to reach it's goal of being pollenated and developing seed. Even by developing it's own pollen sacs.

There are three major phases of growth for all fruit bearing Dioecious plants (having seperate male and female plants). They are:
  • Seedling Phase
  • Vegetative Phase
  • Flower or Bloom Phase
It is inbetween the latter part of the Vegetative Phase and/or the early part of Flower/Bloom phase that Cannabis plants mature sexually. This most often occurs after the onset of Alternating Phyllotaxy. In early stages of vegetative growth, new leaf sets at every node will be parallel to each other. Meaning that the leaf stems (petioles) attach at the same point on the main stem (meristem) when compared to the nodes just above and below. When the plant begins to sexually mature, these leaf sets at one node will be perpendicular (90 degree angle) to the one's just above and below that node. When you begin to see this alternation of leafsets (Alternating Phyllotaxy) from one node to the next, you're plants will be showing preflowers very soon!

Most books and general grow literature you will read will state that you cannot tell the sex of a plant until you are one to two weeks into the Flower/Bloom phase. This is simply NOT true! While not categorically the case, most seed plants will show their Preflowers in the late Vegetative Phase at about 4 to 6 weeks from seed. Even prior to implementing a flowering light schedule. Having said that, this is certainly a strain specific topic. As an example, while an Indica or Indica/Sativa hybrid might show preflowers prior to actual flowering, it may take a long-term Sativa like a Thai or a Haze three to four weeks into a 12/12 light schedule before preflowers are at all detectable. Although rare, you will find the stubborn strain that simply will not show preflowers until the 12/12 flower lighting regime is implemented.

What are Preflowers?

Upon reaching sexual maturity, Cannabis plants will display their "Preflowers" which, essentially, are the first showing of their respective sexual organs. In the earliest stages, these preflowers are almost indetectable to the naked eye and therefore it won't be easy to tell the difference between a male and a female early on.

How do I find these Preflowers?

Initially, the top two or three nodes near the top of the plant, BELOW the highest node (the point where the leaf stems attach to the main stem/meristem), is where preflowers typically appear first. You will need the aid of a magnifying glass or jeweler's loop to actually see them. A 30x magnifier like this one from Radio Shack will do just fine to bring them into sight. They sell for only $8.95.

Focus your attention in the "crotch" of the leaf stem (petiole) and the stalk (meristem). When the plant develops it's preflowers, this is where you will find them. The next diagram gives a good breakdown of this area of the plant.

The Staminate Primordia indicates the male preflower and the Calyx represents the Pistillate Primordia of the female plant. However, note that both the male and female preflowers appear in the same location at the "crotch" area located on the top side of where the Petiole meets the Meristem. Also note that the spear-shaped leaves called the Stipules are NOT the preflowers. This is a common misconception that some have about sexing plants. Some people mistakingly believe that if the Stipules "cross" or point towards each other that this indicates a female and if they point away from each other that would be a male. This is a fallacy. Only the actual preflowers will indicate the sexuality of your plants. The following chart shows the male and female preflowers in a side by side comparison from earliest form to fully maturity.

Note that upon maturity, after the release of pollen, the male staminate literally resembles a flower.

It is important when growing Cannabis to evaluate what your goals are in growing. Are you growing for euphoric or medicinal needs or are you planning on breeding Cannabis? Only in the latter instance will male plants have any usefulness in your garden. Further, it is important to realize that when growing Sinsemilla (seedless female plants) that we are interrupting the reproductive process of the plants for our benefit. We are denying the females the procreating pollen that they desperately seek in order to reproduce. The genetic goal of these plants is to reproduce and further their species but we must prevent this in order to assure ourselves of having those female bud clusters we all desire.

The Male Plant

In general, male plants will be the first to show their preflowers in advance of their female couterparts. This should be a sign to to the grower to watch these plants closely as you will want to cull these plants from your grow if, indeed, they do end up being males. Another notable trait amongst male plants is their tendency to "stretch" and have a general overall taller stature when compared to female plants at the same stage of growth. They will most always be amongst the tallest plants in the garden at any given stage of growth. So, this should also serve as another warning flag to pay particular attention to these plants as they may, indeed, be male.

It is prudent to mention here that what at first might appear to be a male, can and does often end up being female. So, the bottom line is, don't rush to judgement. You have some time before the males will release their pollen and it can pay to be certain before jerking a plant out.

Additionally, male plants will tend to grow "spindly" and sparce in comparison to their female counterparts. The internodal spacing (distance between set of leaves on the main stem) will generally be much wider while the female will have lush growth with much tighter internodal spacings. Here's a full plant shot of a typical male plant. Note the spindly growth and the wide internodal spacings.

At the first signs of preflowers, it is nearly impossible to tell the difference between a male and a female plant. Initally, it will just appear like an indiscernable lump or growth in the "crotch" between the petiole and the meristem.

At this point, the preflower hasn't developed enough to identify the sex of this plant. Here's another that also shows an undetectable preflower.

Photo Courtesy of Small Potatoes

Within a few days to a week or so after the first emergence of preflowers, you will see the Primordia of both the male and the female plants start to change and become more individualistic. As such, this is the time you will be able to recognize the differences between the male and female plants.

In an attempt to describe the sexual organs of plants more vividly, you will hear terms like "Balls" and "Hairs" meant to describe the preflowers of the male and female plant, respectively. In the case of male Primordia, this is fairly descriptive. At the point where male preflowers take on their eventual appearance, they do look like little balls. However, in some cases, they look like a ball on a stick. Here's a shot of a male that really illustrates the "ball on a stick" appearance of the male preflower. However, not all strains will exhibit this trait clearly.

You can see how the ball is "raised" up out of the "crotch" a bit. By comparison, the female calyx will sit down in the "crotch". This can be a fairly discernable difference between the male and female preflowers. So, growers should look for this characterisitic early on.

Photos Courtesy of Small Potatoes

Another descriptive term for the male preflower would be like the shape of a Crab's Claw. As the male preflower begins to open a bit, it will look much like a Crab's Claw. This is another characteristic of the male plant to look for to discover these early on before they can fully open and pollenate your garden.

From this point on, male and female preflowers will begin to look distinctly different. Further, the males will become more apparent as the "balls" will begin to multiply with many balls developing at each node. The balls form in "grape-like" bunches. The next pictures will give you an idea of how this looks.

The clusters of balls on the male plant also closely resemble the budding growth of the Hops plant (used in the production of beer).

Male plants will begin to release their pollen three to four weeks after the preflowers appear. However, this is again strain dependant. Some strains will release later than this (Extreme Sativss being known for this) but, as a general rule, three to four weeks from preflower emergence is a good time frame. This means you will have a three to four week window in which to identify your males and remove them before your whole garden will be pollenated. Or, in the other interest, this is the time frame you will need to be ready in to harvest the pollen from the male, if breeding is your goal.

Here is what male pollen sacs look like after they have release their pollen.

Photo Courtesy of Subcool

As you can see the male staminate has opened and released it's pollen into the air. If there are any females in near proximity (indoors), you now have pollenated female plants.

So, what does male pollen look like? Pollen is a fine powdery substance that is most usually white, yellow or tan in color. In the pic of the open male flower above, you can still see a few grains of pollen attached to the unopened flower within the male staminate. The next pic shows some pollen harvested on a smooth surface.

Photo Courtesy of Bananaman

In this next pic, you can see grains of pollen still stuck to the flowers of this male staminate.

Picture Courtesy of MzJill

Lastly, here is a picture of pollen harvested in a small jar.

Picture Courtesy of thenewguy05

Male plants are the "key" to starting the reproductive process, furthering it's genetic lineage far and wide. Outdoors, this process has remained uniterrupted for millenia. However, if high-grade Sinsemilla is what you seek, the male plants must be culled as quickly after preflowers appear as possible to insure that only unpollenated females remain.

Hopefully, this discussion on Male Plants will help you in identifying them early on. Now you know what to look for, it should be a piece of cake!

Note: All uncredited photos were obtained online through Google Image searches. Photo credits were unavailable. Unless otherwise stated and author credited, this information was not copied and pasted from other sources.