MORE DETAILS, THE MORE YOU TELL US THE MORE WE CAN HELP YOU, i mean we know nothing, Soil/hydro,lights,watering,nuts,schedule, cycle, i can go on and on but we all are here to help but we get frustrated when we come to help and there are so little details like your post, Im sure you did not mean to but please try from now on, I was guilty at first of doing it somewhat and learned if i just take the time to type the correct info when i asked a ? o would get my answer plus ALOT MORE....Will check back but could be anything from nitrogen deficiency to a PH problem...Good luck...