In this article, we'll cover why plant gender matters, how to tell the sex of your plant, why feminized seeds can be helpful, and what to do if you get a male plant.
Overview of cannabis plant anatomy
There are a few stark differences between male and female cannabis plants, some of which you can use to determine the sex, but we'll get to that later. For now, here's a general overview of cannabis plant anatomy.
- Trichomes: Trichomes are the small, crystal- and hair-like structures found on the surface of the cannabis plant. They are expressed through glands on the leaves, stem, and calyx. Trichomes are clear and sticky, protect the plant from harm caused by weather or insects, and contain the chemical compounds that give cannabis its effects, which include flavonoids, cannabinoids like THC and CBD, and terpenes.
- Stem: The plant's main support structure. The stem transports fluid and nutrients up from the roots and provides the plant's foundation for leaves, flower, and colas.
- Fan leaves: Fan leaves are the large leaves that protrude from the plant and support its photosynthesis process. Each cannabis plant may have between five and nine of them. Growers often trim excess fan leaves to facilitate better airflow to the rest of the plant and the excess is usually used to infuse topicals or edibles.
- Node: Where the stem and leaf intersect, nodes are the most important part of the cannabis plant when determining the sex since the nodes are where the plants begin to grow either pollen sacs (male cannabis plants) or pistils (female cannabis plants).
Male plants only:
- Stamen: The stamen is the male plant's reproductive organ and is used to identify male plants. The stamen contains the anthers (pollen sacs).
- Anther: Formed at the end of the male plant's stamen, anthers are the bulbous sacs that produce pollen.
Female plants only:
- Flower: The crown jewel of the cannabis plant, only females produce flowers. The flowers are usually covered with trichomes and are the part of the plant that you buy and smoke.
- Sugar leaves: Typically trimmed off the flower after harvest, sugar leaves are the small leaves that grow around the colas. Due to the high amounts of trichomes they produce, they look as though they are dusted in sugar, hence the name “sugar leaves”. Like fan leaves, excess trim of sugar leaves is used in edibles and concentrates.
- Bracts: Found around the female plant's reproductive areas, bracts are the small leaves that surround and shield the seed pods when they are exposed to pollen from the males. Bracts have resinous glands that contain the highest amount of cannabinoids in the plant.
- Calyx: Enclosed in the bracts is the calyx, which is invisible to the naked eye — it is the translucent layer that covers the female's ovule.
- Cola: Colas are the main part of the flower and form in small clusters at the end of the female's stem.
- Pistil: The pistil is the primary part of the female plant's reproductive system, made up of a single ovule with two protruding stigmas.
- Stigma: Thin strands that extend from the bract in order to catch pollen. Stigmas tend to be white in young plants but turn light yellow or orange once matured. They are commonly used to determine the plant's sex.
Why is sexing plants important?
Many novice growers are surprised to learn that cannabis is a dioecious species, which means that it produces gendered flowers. In times of stress, cannabis can also become hermaphroditic, displaying both female and male sex organs. Sex matters when it comes to cannabis. Female cannabis plants are prized because they grow cannabinoid-rich buds. Male cannabis plants, in contrast, have less THC content than females.
Maintaining a crop of exclusively female plants prevents the possibility of male plants fertilizing them, leading to seed production. Fertilized female plants don't create as much cannabinoid content as unfertilized females. When a female bud is fertilized, the plant's energy and nutrients are directed to creating seeds, rather than forming THC-rich buds. Seedless female buds are known as sinsemilla and are celebrated for their longer bud-producing life and higher THC levels.
When to sex cannabis plants
Young cannabis plants begin to demonstrate signs of gender, or pre-flowers, a month after germination while the plant is still in the vegetative stage. These pre-flowers can appear as soon as four weeks after germination. However, it can take up to six weeks before the male pre-flowers are distinguishable from the female pre-flowers.
While the signs for gender can be subtle, with practice, a dedicated grower can pick them out. A magnifying glass may be helpful as pre-flowers are often challenging to distinguish with the naked eye.
How to identify a male cannabis plant
Male plants often, but not always, reveal their sex a week or two before female plants. Male plants produce pollen sacs, which also grow at the junction between the node and the stalk. When they first form, the male pollen sacs can initially look similar to the tiny buds that appear on female plants, but they do not have stigmas protruding from them. The male pre-flowers also take on more of a spade-like shape than the tear-drop shape of the young female bud.
There are other morphological differences that distinguish males from females. The male plant frequently grows taller than its female counterpart and has thicker, sturdier stalks to support its weight. Male plants also have fewer leaves, which tend to be shorter and bushier.
How to identify a female cannabis plant
In the pre-flowering phase, the main giveaway of a female plant is the stigmas protruding from tiny tear-drop-shaped buds.
The wispy, white hairs of the female stigma become visible approximately four to six weeks after germination and progressively darken over time. Pistils and stigmas are more likely to appear closer to the top of the plant near the light source, but they can also form in the lower regions.
What to do with male cannabis plants
Male plants don't need to go to waste. Some growers choose to keep male plants for breeding purposes in order to introduce greater genetic diversity into their crops. Aside from that, many growers use the plants to bulk up their compost piles, make edibles and concentrates, or turn the leaves into cannabis tea or juice.
FAQs about sexing cannabis plants
What are hermaphrodite cannabis plants?
Hermaphrodite plants, or “hermies” as they are sometimes known, grow both male and female sex organs. Some cannabis cultivars — such as Thai Sativa — are true hermaphrodites with the tendency to express hermaphroditism in their genes. However, hermaphrodite plants generally occur as an outcome of stress, such as photoperiod disruptions, nutrient deficiencies, or disease. It's vital to check female plants carefully to ensure the buds are female, and there are no male flowers that could result in the plant fertilizing itself.
Two signs indicate a plant is hermaphroditic. The first and most obvious sign is if the plant grows both male pollen sacs and female buds. The second sign is the appearance of anthers, known colloquially by growers as bananas or “nanners.” Anthers have a curved shape, are typically yellow or lime-green, and appear among buds. Unlike regular male pollen sacs, these can fertilize the female plants as soon as they emerge, so they must be immediately trimmed or removed to protect a female crop.
What are feminized seeds?
Feminized seeds are seeds that have been cultivated to produce only female plants, the plants should grow to be exclusively female. There is a chance that you'll catch a male plant growing from a feminized seed, but it's rare, especially if you're getting your seeds from a reputable and trusted source.
With non-feminized or regular seeds, approximately half the plants will turn out to be male.
How can you tell the gender of a seed?
There is no way to determine the gender of a cannabis seed unless you've purchased feminized seeds from a reputable grower.
Feminized seeds almost exclusively produce female plants; however, you should still check your crop to ensure no rogue male plants have snuck in. Feminized seeds can also become hermaphrodite plants in times of stress, particularly if they come from dubious genetic lines.
Do male plants produce buds?
Male plants don't produce buds. The male sex organs of the cannabis plant instead produce pollen sacs that are designed to fertilize the female bud and form seeds.
Seedy female buds are undesirable as they provide lower-quality cannabis. It's essential to remove the male and hermaphroditic plants from a crop as soon as possible to protect the quality of the female buds.
What is chemical leaf testing?
One method of checking gender is to perform a chemical test of the plant's leaves. This method can be used on a plant as soon as one week after germination. Chemical testing requires a small amount of plant tissue, such as a punch-out from a leaf.
While it is a more expensive option than a visual inspection, it is becoming more common among breeders who want to know the gender of their plants early and definitively.