Check it out! You'll find it anywhere online that colder temps for your night can/will bring out the purple's/blues in a strain! Tho some are just naturally purple .. but Normally a 15 degree difference between your days and nights can cause the purple to come out! (like in fall temps how the leafs change on the tress!) Tho not all strains will As I've read! try to keep it within the 50 range..( stay away for 40's! ) after a certain point it can cause plant growth to slow down. so experiment!!! not every strain will turn purple! some more then other's
Right from high times!
"The origins of purple cannabis are as much of a mystery as the origins of the plant itself. However, purpling is as natural as the changing colors on the leaves of deciduous trees in autumn, which is attributed in part to the pigment anthocyanin. Anthocyanin expression is controlled by both genetic and environmental factors"
They say you learn something new everyday! even if its something useless!