I'm still pretty new to growing myself but I think I have a handle on telling the sex of my plants, I bought a 60x cheap microscope that clips on my phone to get some good pics. These plants I started from seed about 2 months ago. I didn't know what they were but figured i would give them a try. The pic with more purple is a female the other is male the pic with both plants the bigger is the female and for reference that's a gallon bottle in the background, currently on 18/6