Cal. Snow

Hey Growmie, Purple stems and branches could be caused by several things. Some of the natural causes could be plant maturity and genetics, there could also be environmental factors like lighting and temp fluctuations at night that can also cause this. Something else you can check would be if this is from a deficiency, such as Phosphorus, Magnesium,Potassium, or Calcium, all these deficiencies start with purple or red stems and then it starts getting worse.

Your plant is asking you for a little more of PK. ^^

Purple stems can be genetic, but it's typically caused by lack of Phosphorus. Purple striped stalks are a sign of magnesium deficiency.

Buy a P/K booster, either mineral based or organic!