When you grow cannabis plants, they will either turn out as females, males, or hermaphrodites, meaning a hybrid of the two sexes. Knowing the difference between the three is vital to maintaining a strong growing operation, whether you’re planning on crossbreeding strains, maximising the yield of your female plants, or studying each of the types.
Cannabis, like those who love it, doesn’t always stick to the rules, though. Sometimes, this dioecious plant species goes against the grain and develops both male and female reproductive organs. These specimens are known as hermaphrodites. Either genetic or environmental factors, or both, can cause plants to develop this unusual trait. Having both buds and pollen sacs, they end up developing the ability to pollinate and reproduce with themselves.
WHY DOES IT MATTER THAT CANNABIS IS DIOECIOUS?
These protruding structures are designed to capture pollen, which leads to fertilisation. They stick out away from the flower to capture pollen from the air, and to await being brushed up against by pollen-covered insects.
Despite their differences, all female plants share one thing in common: they produce flowers. These flowers, colloquially known as buds, possess small glandular structures called trichomes that produce cannabinoids such as THC and CBD.
Male and female plants look identical during the seedling and vegetative phases. But, as they begin to transition into the flowering phase, plants finally begin to reveal their sex. During this time, females produce resinous buds loaded with cannabinoids, and males form sacs filled with pollen.
Female plants usually take several days longer than males to develop pistils or female sexual organs. The pistils look like small green seed pods and have white v-shaped stigmas, or thin hairs, which extend from them. Female plants are generally shorter, denser in foliage, and broader than their male counterparts.
The sex of a plant is determined by its genetics before germination even begins. With the sex genetically encoded, there is no way to make a male plant female, or a female plant male. There are techniques that can be used, however, to encourage a male plant to display female characteristics. These techniques require the use of chemicals, such as ethylene , to prompt a hormonal response from the plant.
A hermaphroditic plant, by definition, contains both female and male sex organs. Photo by: Gina Coleman/Weedmaps
Can you turn a male plant female?
Finally, swiftly remove any male flowers that appear. If the plant has very few male flowers, those flowers can be removed, but the plant will need to be watched closely. Plants with many male flowers should be eliminated entirely.
Like all plants, however, cannabis has an inherent drive to procreate by propagating seeds. One way that the plant achieves this is by herming, when female plants become hermaphrodite to self-pollinate. The tendency to herm means that growers must take extra care to minimize any stressors that may cause the plant to perceive a threat and change its sex.
Other stressors that may incite female cannabis plants to become hermaphroditic include disruptions to the photoperiod, dramatic shifts in temperature, disease or pest infestations, the use of toxic pesticides, and physical damage from vigorous pruning.
“Herming can also definitely be a genetic problem, but it is not cultivar-specific,” says Perlowin. “You can get the same cultivars from different seed companies, and they will yield different results.” Reputable breeders are more likely to competently sort and select seeds from genetically robust plants with desirable traits.
Male plants won’t show hairs at these nodes, but will develop little sacs of pollen. These pollen sacs will look like little balls. These balls can appear on their own or in clusters, depending how far into the pre-flowering stage the plant is. At some later stage of growth, the pollen sacs will burst open, spilling the pollen and possibly pollinating your females.
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.
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.
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.
Obviously, no one wants to smoke seedy weed. When you grow cannabis and learn how to identify male plants and signs of pollination, you can remove these plants to save your remaining females. Likewise, recognising a pollinated female early allows you to start again before it’s too late, rather than finishing a grow that will only result in a poor-quality 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.