Hi Tom
Jerry Meislik has some nice articles:
http://www.bonsaihunk.us/cultural.html
Photoperiod can influence flowering and dormancy. When I used lights outdoors it was not really for growing purposes (so I don't have much experience with that subject) but rather just as heat sources (incandescent lights are pretty inefficient and make nice heaters). So I was actually running them in the very early morning when it was coldest.
Regards,
Matt