Posted: 07/10/2013 at 17:04
IME thyme dislikes to be shaded by any other plant, so a separate pot for each may be an answer.
Gritty, poorish MP compost, NOT a substantial one like JI3, would be best for herbs. Dont forget to wrap the pot for the winter, the roots mustnt freeze. Also stand the pot on 'feet' to help keep the drainage. Full sun position, if possible.
I must admit that everytime I've tried sage in a pot it ends up 'unhappy' despite my best efforts with compost quality & drainage, sun etc. I did however put a sage plant into a sunnyish spot in very shallow soil, barely 6'' in depth, overlying the brick sub-straight (i think that's what you'd call it) at the patio edge. The plant is huge & obviously very happy, despite the previous 2 cold winters. The poor thyme however, in an adjacent patio crack, is completely swamped by the sage, so cuttings of it are now in the coldframe! J.