Turning purple is it because of cold temps?

[Jlee]

Is it because of cold temps? It’s a gorilla glue. I have four more of the same thing they’re not turning purple.

 

[Ninjadogma]

Is it because of cold temps? It’s a gorilla glue. I have four more of the same thing they’re not turning purple.

I'm thinking it's just genetic expression, not temps. With cold I would expect to see more phosphorus disruption. Also, up to a point, you can even get a ballpark of where your pH is sitting by the expression color. Purple is right in the middle... Low pH appears more red and high pH appears more blue. It's not fully reliable though. There's red stem varieties that screw that up and pH doesn't factor.