I agree with duck--autos generally do best with 20 hours of light a day. Since they have a set life-time you want things to be as optimal as possible. Taller deeper pots tend to work best. I think some auto growers used tree pots which are narrower and deeper. If growing outdoors, I would also recommend going with photoperiod plants. However unless you are near the equator, this is a question for next spring, isn't it?