Go get a farmers almanac, it has all the sunrise/sunsets schedules in it as well as first/last AVG. frost dates. Dont worry about sunlight hours,worry about temps and frost.Are you planting seeds/seedlings or well established plants? If you have well established plants that have been under say 18/6 lights, if they go outside under less hrs of light they may slow growth a little, possibly try going into flower? but once they get acclimated they should get back into veg.