Plants that turn colors have the gentetics to do that. But lower temps really bring out the colors. I'm sure someone out there knows alot more about why plant have the different colors. Here I found alittle read on it;
The reason some strains of marijuana turn purple is the same reason why some trees leaves turn colors in the fall, why red grapes are purple, why a blood orange is so red, why an eggplant is purple, why blueberries are blue, and why black raspberries are black. This phenomenon is caused by the occurrence of something known as anthocyanin accumulation which causes anthocyanin to build up within plants. While chlorophyll is what gives weed and plants in general their green color, anthocyanin is what makes weed purple, and carotenoid is what will make weed yellow or gold.
If your plant has the genetics which make it prone to anthocyanin accumulation, you can make it turn purple by dropping the temperatures in the growing environment down below 50 degrees Fahrenheit when the light is off. During flower you should be on a 12-12 cycle or something very close. Some plants will turn purple without such a drastic drop in temperatures, and like I said before, for some plants it just isn’t possible.
yea Sue,, I just pop them in baggie.. And welcome Purple Gun Rack. Read hell I just like looking at pics.. JK Keepem Green