I know outdoor and indoor are different. I was just stating that lowering temps indoors to get better coloring is natural and not a gimmick. It happens in nature when changing from summer to fall. I personally don't purposefully lower temps, my grow space gets cool enough at night(65) for my strains to color up just fine. Strains like GDP and Purple Urkle are genetically purple but lower temps increase the effect. There are strains that will throw down pure purple color from the beginning of flower like Black Rose, Double Purple Doja, Sweet Purple, Purple Pakistan Chitral Kush, Purple Goddess etc.... regardless of temps. Here are a couple pics. First pic is Purple Urkle which starts off green and then starts to put on the color later in flower. Next is Purple Goddess, as you can see she puts down the Purple from the beginning of budset.