Why Does Marijuana Turn Purple?

Marijuana is green because of the drying process. Instead of being heated to dry like tobacco (which would destroy the THC content) it is hung (upside down, roots up), then air dried for a period of time, thus sustaining important plant ingredients such as chlorophyll. THC is a more heat-sensitive chemical than nicotine; so the process has to be as it is so the plant matter does not lose it's medicinal values.