There are a number of purple strains.
I just got Grape ape and another called Mr. purps. I've also seen Purple passion and really purple Grandaddy X grape ape. I'm sure there are 20 more purple stains.
I believe I read some of the purple stains require a cool period during flower to turn purple. However it's been a while since I read it, Thus I have no clue where it was. :jointsmile: