Athosanswered grow question 6 years ago The plants need 12 hours of UNINTERRUPTED darkness to flower, which means that something like 6/6 will not trigger flowering. What I've read about is something called extended light schedule: With a digital timer, you set lights for periods of 21:36 hours (21 hrs 36 mins) and lights off periods of 12 hours), this will give you an exact week that has 5 extended days (for a total of 33 hours 36 mins per "day"). The data I read states that the aditional light hours increases yield. Also important, going over 21 or 22 hours of light does nothing since there's a point where the added light reaches a saturation point and the plant can't use it. I havent tested it though