Quote Originally Posted by Minnesnowta
drudown idk about you but I've noticed that stem color can sometimes be a poor indicator of phosphorus deficiencies. I am guessing thats why you're asking about the stem color? I think it varies greatly by strain. I have a strain that always grows with red stems and loves it, but it also doesn't have any purple color changes in the bud or anything like that without being forced.
Its not always a deficiency! Pretty much any plant under stress with turn a purple/red color.... Having said that a deficient will cause stress. I do mostly hydro in rockwool so nute deficiencies are not real common for me but pest issues and liquid light both cause the stems to change!