There are hundreds of different types of, 'purple' colored MJ. Figuring out which one is yours will be a difficult task as it could be either the genetic that makes it purple, or the cooler temps, which could be thousands of different kinds.

I grew some MJ outside a few years ago as I ran out of space in my GR. I planted them on a hill and they were green at the time. I never fed them or nothing, just left them on the hill. I went back like 3 months later, and they were a deep colored purple from the cool temps we had that year.

Anyways, I remeber that because it was potent as fuck too. Peace