Sexing cannabis plants is really just finding out whether they are male or female, this can be very important for various reasons, ranging from a breeding project to extensive phenotype hunting. Knowing how and when to tell if your plants are male or female will give you an advantage when growing indoors. In this article, we explain how to tell the sex of your Cannabis plants, what traits to look for, and what can go wrong. When growing from seed, Cannabis plants will spend the earliest stage of their life cycle focusing on the root, leaf, and stem production. After your plants grow to the 6th or 7th internode, you will be able to identify by eye potential male or female traits. Cannabis plants that are put into flowering from the seedling stage, will still require weeks before the first signs of pre-flowers appear.