Examine the nodes of the plant and look for either the early growth of small sacs on a male, or two bracts on a female, which will eventually produce the hair-like stigma.
“Herming out,” as some call it, is something that generally happens when a plant becomes excessively stressed. Some stressors include:
Branches grow out of the main stem and support fan leaves and buds. Growers often train a cannabis plant by topping branches to create more bud sites.
Males and females are usually only pollinated when crossbreeding plants or creating new strains.
Fan leaves are the large, iconic leaves of the cannabis plant. They capture light for the plant and typically have little-to-no resin and are usually discarded when trimming.
Mycorrhizae, a beneficial fungus, can be added to soil to improve root systems.
A node is a point at which a branch grows off of the main stem, or one branch from another branch. Fan leaves and buds can grow on some nodes, but not necessarily all.
A guide to differentiating between male, female, and hermaphrodite cannabis plants.
Male pre-flowers look like tiny green eggs or “balls”. These young pollen sacs will look smooth and won’t possess any fine hairs, or any distinct point. Later into the flowering stage, pollen sacs begin to form larger and denser clusters. They’ll become easy to identify with the naked eye by this point. However, pollen sacs usually begin to disperse their contents around 2–3 weeks after forming. Be sure to remove them from your space with haste if you don’t plan on crossing your plants.
WHY DOES IT MATTER THAT CANNABIS IS DIOECIOUS?
Male plants, in contrast, don’t produce flowers. This makes them less valuable for growers seeking only buds. However, they do produce pollen sacs. These small vessels create the genetic material required to fertilise female flowers and create hybrids. This makes the males extremely important for breeding new cannabis strains.
Cannabis growers and breeders use this trait to their advantage, since it allows them to separate male and female plants. This enables them to prevent the flowers from becoming fertilised and going to seed, which results in better quality flowers, known as sinsemilla.
Growers identify plant sex by identifying pre-flowers, which are small structures that form at the nodes during late vegetation.
If you see wispy white hairs appearing on your plant like the ones pictured below, then you know you have a female plant.
Note: Once the plant is about 6 weeks old from seed, it will usually show signs of “pre-flowers” which will alert you to the gender before the beginning of the flowering stage.
When do marijuana plants reveal their gender?
These male plants can also impregnate your female plants, which causes them not to produce as many buds, so unless you’re breeding, destroy male plants as soon as you notice them growing grape-like balls where their buds would normally be.
In the wild, as the days get shorter and nights get longer, the marijuana plant “realizes” that winter is coming and will start budding/flowering as it approaches the end of it’s lifecycle.