Red stems can be genetic or it means it's hungry. The chart I have says that red stems means a deficiency in N, P, K, and/or Mg. So it might just need more food or a little epsom salt or something. I would try feeding it more first though and see if that solves the problem. It might be genetic too- you are just going to have to try a few things to see what's going on.
I wish I was going to the cannabis cup this year
