Sexing Cannabis Plants
Whether you are germinating marijuana seeds or growing new plants for a pheno hunt, it is essential to understand how sexing cannabis plants work.
Sexing Cannabis in the Vegetative Stage
Not all strains of cannabis will display their sex in the vegetative stage. Environmental factors can play a significant role in how your plants develop and mature. For example, if your environment is too hot or cold, or too humid or dry, stress can start to cause your seedlings or young plants to undergo adverse changes. Many people like to follow the VPD (vapor pressure deficit) chart to help them determine the proper environment relative to their temperature and humidity levels.
After germinating cannabis seeds and allowing them to produce a healthy root mass over a few weeks to a month, the plants may begin showing their sexual traits. What you are looking for when identifying the sex of a cannabis plant is the development of either pistil hairs emerging from a pistillate calyx (female) or tiny round-shaped balls (male). You can use a jeweler’s loop or hand scope to get a close-up look. Females will have a calyx on either side, located at the node where each petiole branches off the stem. Not every branch will show sex, so always make sure you thoroughly examine every location along the branches. This is especially important when screening plants for any hermaphroditic traits (both male and female).
When sexing cannabis, plants that appear to be female can be hermaphrodites that haven’t shown their true traits yet. The term “hermaphrodite” refers to the presence of two sexes in one plant. Therefore, it is possible that plants displaying female traits in the vegetative stage could become hermaphroditic and produce male pollen once they enter the flowering cycle. If a plant is going to become a hermaphrodite, it will likely happen within the first three weeks of flowering; however, some strains take as long as five weeks. Male parts will form either independently on the plant or from within female parts. As a result, it is often tough to identify these traits if you are not examining every bud site on the plant.
If you see male traits such as the growth of little balls or what many refer to as bananas (staminate), you should immediately remove the entire plant to avoid pollinating the other plants in the grow room. Not all hermaphroditic parts produce viable pollen. Sometimes you can get lucky, and the hermaphroditic plant won’t pollinate your entire grow room. Regardless, you don’t want hermaphroditic marijuana plants in the garden. Remove them quickly.
Sexing Cannabis in the Flowering Stage
Once you have entered the flowering phase, all the plants in the room will show their true sexual traits. Over the first few weeks, you will need to pay close attention to the bud sites on your plants.
Although you may have removed all the males during the vegetative stage, female plants can often display hermaphroditic traits rapidly, pollinating entire grow rooms overnight. When flowering phenotypes for the first time, it is recommended to “lollipop” the plants by removing all the lower branches and foliage. You want to do this because plants will often herm on the lower areas if they are unstable. Removing the lower vegetation will also make it easier to thoroughly examine the whole plant every day as you wait for it to reveal its sex.
Many strains will not show their sex until they are a few weeks into flowering, so please be patient. Female plants will display calyxes that will come to a point and surround two pistil hairs that will emerge from within. In the flowering stage, males will display staminate flowers at the same node sites that females form pistillate flowers. Staminate male calyxes will appear around the stamens, where pollen is produced. These stamens are often referred to as bananas because they look like a bundle of bananas hanging off the plant. Males will commonly show one or two balls before they emerge into staminate calyxes. With proper knowledge and practice, you will be able to identify the sex of your cannabis plants quickly and easily.