Red stems have been from bad soil for me, red stems are a symptom of a deficiency of N, P, K or Mg. My symptoms are limited to only slight reddening, so I assume it to be a deficiency of N
They seem to be doing well even if I shouldn't have fed them, though I'm pretty sure I should have. Remember it's a light mix they're in, not an allmix so it's lightly fertilized
Yeah light mix should be about 3 week's and all mix about 6.