2nd grow indoor outdoor

I topped one of my plants to try out this method to enhance the cola yield but after a week or so my stems went from green to purple. The other 2 that I didn’t top are fine. All are getting the same nutrient water mixture and sunlight/indoor light. I read it may have something to do with...

Howdy folks. Its been an entire year but, here i go again. This is not the grow I was hoping to be doing but it will still be fun. I appreciate all viewers/commentors. I have a 28 plant aero flow system with 1000 watt hps on ,stand-by, hopefully it wont be a year before i get that one going...