Purpling from cold is different, would affect leaves too and turn them purple, 80/90 is good temps, maybe i little too hot at times but its fine. Leaves and stems look cal/mag deficient but it looks underferted as well also the small little plants round it seem to be suffering with the same affliction, dead give away. Still details would help other than that shoot some ferts its way and some cal/mag to be sure. Peace