Most flowering plants use pollen to reproduce through a process known as pollination. In nature, plants have developed specific flower parts which attract pollinators or are designed to distribute pollen by the wind or water cycle. For the vast majority of flowering plants, both the female and male reproductive organs are present on each individual plant. This automatically increases the plant’s likelihood of pollination and, in turn, reproduction. In dioecious plants, however, the male and female reproductive organs are found on separate individuals. Cannabis is a dioecious plant and, therefore, can be found in either male or female form.
For most marijuana growers, the male plants are unwanted and should be removed entirely from the growing facility. If a male plant pollinates a female plant, the female will begin to develop seeds. Once a female flower develops seeds, the quality of the marijuana is diminished. In other words, the potency, flavor and smoothness of the finished product are not as good as they would be otherwise. Cannabis breeders, who are deliberately trying to pollinate the female plants to create seeds, would be the exception to growing exclusively female plants. Marijuana growers who wish to have the highest potency product and biggest buds will always remove male plants from the garden before they have a chance to pollinate the female plants.
Before you can understand what to look for when determining the sex of a cannabis plant, you must know when to look for it. Marijuana plants go through three distinct stages of growth throughout their life cycles. The first stage is the seedling stage. This is the earliest stage of growth and is when the plant first develops a root system and leaves. The second stage of growth is the vegetative stage. It is during this stage that the majority of the plant’s structural integrity is developed. In other words, the roots, stalk, and leaves all take shape and grow bigger and stronger throughout this stage. The third and final stage of growth for the marijuana plant is the flowering stage. In this stage of growth the flowers begin to develop and, eventually, mature into the buds that are harvested. Identifying the sex of a cannabis plant is commonly done in the flowering stage. Although there are some tell-tale signs to look for in the vegetative stage, a marijuana plant must begin to create its reproductive organs in order to positively identify the sex. This occurs in the final (flowering) stage of growth.
During the vegetative stage of growth, growers can look for some signals that might help identify a male plant.
Plants that are tall and very thick should be on a grower’s radar as possible male plants. Sporadic branching and fewer leaves during the vegetative stage are other indicators that the plant might be a male. Once the flowering cycle has begun, it becomes much easier to separate the male plants from the female plants. For outdoor plants, the flowering cycle will begin as the amount of sunlight per day is shortened to around 14 hours. For indoor gardens, the flowering cycle is triggered when the grower changes the photoperiod to a 12 hour light/12 hour dark cycle.
Once the flowering cycle has begun it is very important for the grower to regularly monitor the plants. Unsexed plants should be monitored daily, if not twice a day, to check for indicators of male reproductive organs. When a male plant begins to show its reproductive organs, it will appear to have a tiny bunch of bananas (green in color, not yellow) at the inner joints of the branches. As soon as these “bananas” are spotted, the plant should be removed. It is important to remember that the damage done by pollination occurs after the male plants have released pollen. As long as the plants can be positively identified as males and then removed from the garden before the pollen is released, no seeds will develop.
Growing seedless female marijuana flowers is what most cannabis growers are trying to achieve. The term sinsemilla is commonly misunderstood as a specific strain of cannabis. Sinsemilla is a Spanish word that translates to “without seed”. In other words, when cannabis growers refer to sinsemilla, they are talking about female flowers that have not been pollinated. Like male marijuana plants, it is almost impossible to positively identify female plants until they have started to develop their reproductive organs. During the vegetative stage, plants that have more leaves or have close spacing between branches show early signs of being female. Once the flowering stage begins, the female plants will develop what look like tiny white hairs at the joints and base of the branches. The white hairs (pistils) grow in pairs and will eventually turn red in color as the flowers develop.
After a grower has removed all of the male plants from the garden, it is important to closely monitor the remaining female plants for hermaphrodites. In some cases, female plants will begin to grow male flowers (hermaphrodite) and begin to pollinate themselves and any other plants in the area. For indoor growers, it only takes one hermaphrodite to seed the entire crop. This is why daily monitoring is so important when the cannabis grower is starting from seed. We still don’t fully understand all of the reasons why hermaphrodites occur. Some people believe that it is unnatural for only female plants to occur so hermaphrodites are nature’s way of balancing the scales. It has also been shown that hermaphrodites tend to develop in response to environmental stresses. Out of whack temperatures or humidity and/or light leaks during the dark cycle are all possible triggers for a hermaphrodite to develop. Whatever the reason, when identified, hermaphrodites should be immediately removed from the garden. Hermaphrodites do not always appear during the development of the initial reproductive organs. In fact, it is quite common for hermaphrodites to occur later in the flowering stage. Again, this is why monitoring on a regular basis throughout the entire flowering cycle is so crucial.
The removal of male and hermaphrodite plants in a timely manner is the most effective way to diminish the possibility of pollination. If, for some reason, a male plant is not identified early enough or if a hermaphrodite develops in the later stages of flowering, some extra caution should be used when removing. Extra care should be taken because the pollen sacs on more mature males or hermaphrodite marijuana plants can open up and release pollen. Once released, pollen can quickly pollinate every plant in the garden.
If a male or hermaphrodite is spotted in the garden, immediately turn off all fans. In nature, cannabis is mainly pollinated via wind, which means any air movement will increase the release of pollen from male or hermaphrodite plants; keeping the fans off when removing the unwanted plants will help reduce pollination. Only turn the fans back on after the male or hermaphrodite has been removed. After turning off the fans take a spray bottle filled with water and completely saturate the pollen sacs on the identified male or hermaphrodite plant. This will reduce the amount of pollen that can travel by air when the plant is being removed. It is even a good idea to cover the unwanted plant with a garbage bag to further contain any released pollen.
Unfortunately, if the problem is identified in the later stages of flowering, some damage is bound to have occurred. However, minimizing the issue can go a long way in salvaging the remainder of the crop. Again, this is why daily monitoring is so important for cannabis growers who start their crops from seed.
The vast majority of cannabis growers have their sights set on producing large, female marijuana flowers. When starting from non-feminized seeds, a grower has about a 50/50 chance of getting a female plant. With potentially half of the plants developing into males, early and accurate identification is crucial to preserving the final quality of the cannabis flowers. When a marijuana plant begins its early stages of flowering, it will begin to develop its reproductive organs. Distinguishing between male and female cannabis plants is not difficult when you know what to look for. Identifying hermaphrodite plants can be a little more difficult. For the most part, hermaphrodites will look like any other female marijuana plant. The only way to catch a hermaphrodite in time is daily monitoring of the plant’s flower development and becoming a watch dog for pollen sacs.
Unfortunately, it doesn’t take much to seed a crop of female marijuana plants. Each pollen sac contains enough pollen to seed an entire garden and greatly degrade the value of the cannabis. Indoor marijuana growers take many steps to mimic nature in an enclosed environment. Pollination is the big exception to this rule. In nature, reproduction for flowering plants starts with pollination. In a cannabis garden, pollination equates to a lower return on investment. Marijuana growers who accurately identify and promptly remove male and hermaphrodite plants will be able to enjoy a grow room full of sinsemilla flowers and are more likely to receive a profitable harvest.
Eric Hopper resides in Michigan’s beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability. He is a Professional Marijuana Grower Senior Editor.