Elevated levels of female hormones in male cannabis plants can trigger female flowering development. The technique is more effective when applied to male plants that have not yet formed mature flowers. It’s also vital to bear in mind that many male marijuana plants are hermaphroditic plants, and distinguishing true males can be very difficult.
Author Robert Connell Clarke’s book Marijuana Botany An Advanced Study: The Propagation and Breeding of Distinctive Cannabis presents clear instructions for differentiating male and female plants. The gender of a cannabis plant is located at the nodes along the main stem.
Female plants are generally shorter, denser in foliage, and broader than their male counterparts. Photo by: Gina Coleman/Weedmaps
Can you turn a male plant female?
Herming can also have a genetic component, with some growers viewing plants that are inclined to herm as genetically inferior.
When female plants herm, or develop male flowers capable of disseminating pollen, the entire crop is at risk of pollination. Female flowers that have been fertilized by pollen will halt their development to produce seeds, limiting flower production.
According to Perlowin, stress is the fundamental cause of hermaphroditic plants, or ‘hermies.’ “Some examples of stressors would be not enough water, too much water, not enough nutrients, or too much heat. It can happen at any time in the life cycle of a plant from a new plant to a very mature one,” explains Perlowin. The female plant will develop male flowers in response to stress, to ensure seeds are produced before the environmental trigger can kill the plant.
Perlowin advises that growers who wish to prevent female cannabis plants from herming must be diligent throughout the plant’s grow cycle. For starters, purchase seeds from a reputable company or trustworthy breeder that understands cannabis genetics. While potential environmental stressors must be monitored and minimized, growers should also examine their plants every day for any unusual growth.
To determine the sex of your cannabis plants, you will have to wait until the pre-flowering stage when plants begin to put their energy into reproduction. Female cannabis plants show their gender signs later than males. At the location where they will soon grow their buds (the nodes between the stalk and the stem), females will show wispy white hairs.
Pollination of your female cannabis plants will make them produce seeds and spend less energy on producing quality buds. But when you recognise the signs of pollination early, you can avoid putting time and resources into a poor harvest.
Among the early signs that your female has been pollinated is that her bracts become larger. Bracts are small, leaf-like structures that protect the female’s reproductive parts. These are the sites from which the flowering buds appear. Do not confuse the bracts with calyxes.
WHAT TO DO WHEN YOUR FEMALES GET POLLINATED?
Another indication of pollination can be the colour of her pistil hairs. When a female has been pollinated, the previously white hairs will soon shrivel and become darker.
There is a good reason why most growers keep male plants away from their ladies: Pollination from males causes the females to develop seeds. As a result, females focus their energy on seed production, rather than on growing you some fine-quality bud. This seedy and unfortunate final product can be avoided by implementing a few basic techniques.
A good test to see whether the bracts have swollen is to take a pair of tweezers, grab one bract, and open it up. If there is a seed inside, you have a pollinated plant.