How long they are under lights a day depends on alot of things. Anywhere between 18 and 24 hours of light. You gotta wait a bit to sex the plants. I assume yours are still young sprouts? Share a lil more specific info and someone will most def help you. Im new here as well. Grew alot a long time ago. I got an outdoor grow i'm about 8 days into. Chek out the basic growing forum here and most of your questions will be answered. Chances are we all ask the same shit, you know. Also, read other peoples grow logs, and you will learn alot. Watchin a pro helps alot. Good luck!