Whether you are germinating seeds or taking in new plants for a pheno hunt, it is essential to understand how to identify a cannabis plants sex if it hasn’t already been determined.
Sexing Cannabis in the Vegetative Stage
Not all genetics will display their sex in the vegetative stage. Environmental factors can play a significant role in how your plants develop and mature. If your environment is too hot or too cold or too humid or too dry, stress can start to cause your seedlings or young plants to undergo unhealthy and otherwise unlikely 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, you may eventually be able to see the plants 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 with. Females will have a calyx on either side or both sides 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, so you do not overlook anything. 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 that display female traits in the vegetative stage could become herm and produce male pollen once they enter the 12 on 12 off light cycle. If a plant is going to herm, it will likely happen within the first three weeks of flower but some genetics can herm as late as week five. What will happen here is that male traits will form either independently on the plant or from within female parts. It is many times very hard to identify if you are not examining every site on the plant with stringent regard.
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 if you want to make sure you avoid pollination in the grow room. Not all hermaphroditic parts produce viable pollen. Sometimes you can get lucky, and a hermed plant won’t seed any of your grow room or maybe just a few closest plants. Either way, you don’t want herms in the garden. Remove them.
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 especially close attention to the sites on your plants that signal their sex.
Although you may have removed all the males in the vegetative stage, female plants can often produce hermaphroditic traits and pollinate entire grow rooms overnight so be alert. When flowering phenotypes for the first time it is recommended to bottom-up the lower part of the plant by removing all the lower branches and foliage. You want to do this because often plants will herm on the lower areas if they are unstable and also to make it easier to examine the whole plant thoroughly every day as your watch for the sex to appear. Many genetics will not show their sex in the vegetative stage or until they are a few weeks into flower so be patient. Female plants will display gorgeous 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 as females would show pistillate flowers. Staminate male calyxes will appear and form around the stamens where pollen is produced inside. These stamens are often referred to as bananas because they have a similar look to a bundle of bananas hanging off the plant. Males will show one or two balls commonly before they emerge into staminate calyxes. With the proper knowledge and practice, you will quickly be able to identify the sex of your cannabis plants and work confidently as you move from one pheno hunt to the next.