There is a method called 12/12 from seed. You run your lights 12 hours a day from seed. Plants will only begin to flower when they have matured enough essentially. You are usually dealing with 21-30 or 35 days of veg growth and 8 weeks of flowering. By doing your growing this way, you are able to always run your lights at 12 hours a day. You just need to make sure to produce some seeds from time to time in order to keep this method going. I use this method sometimes. Most of my plants end up just under 3 ft in height.