Pre-flowers are the beginnings of cannabis plant sex organs. If you’re growing regular seeds, you’ll likely have a mix of male and female plants and will need to determine the sex of your plants to discard the males. It’s imperative to separate males so they don’t pollinate the females.
Pre-flowers appear at the nodes of the plant, where a branch grows out of the main stalk. Females will develop an oval-shaped bract with hairs or pistils sticking out, while males will develop round pollen sacs.
Learn more about pre-flowers and cannabis plant sexing in our anatomy article.