Always have some kind of air movement in the grow area or the plant is not getting fresh air.Get hold of a fan this will tougthen the plants makeing the stems nice and thick.If you don't have a exaust fan then at least cut a couple of fresh air holes in the room and run some ducting in this will take fresh air in while takeing all the stagnent air out.By useing ducting this will cut down on light leaks from the grow room but do the plant a world of good.A cheep way of makeing a exaust fan out of a ossalateing fan is have one ossalateing fan blowing at the hole where the ducting is this will force air out of the room.And another to keep fresh air moveing aroung the room.......................tyke..............................................................