How do you tell difference between male and female marijuana plants?

Well you have to wait until the plant starts to matures. The first thing youll notice on a male plant is these little balls at the main stem, where the leaves come out that. They end up turning in to flowers. A female would grow two hairs from the main stem called pistils. You will just have to wait until the plant gets old enough for you tell one from another. In the begining of the flowering stage you are not going to be able to tell the difference, if you have never done this before. google "male marijuana plants". Then click on images.That should help you out a lot.