Hi guys! I jut got some timers for my lights, and I'm wondering how long I should have the lights on. I understand less in winter than summer, but I don't know exactly how much
There isn't any stated amount of time, though I think it's been demonstrated that beyond about 14-15 hours there is no advantage in lengthening the time. I vary mine from 12-15 hours, increasing the length of time a half hour a month from January to June and decreasing it from July-December by the same amount. Nothing scientific about that - that's just what I've always done and it seems to work well for me.
I tend to go with the length of daylight outside, but stop decreasing around December as tropical plants get more light than U.S. native plants during the winter months.