I bought an autumn sage a few days ago, it had a few yellow leaves on the bottom but it seemed fine.
However now there's yellowing and browning in the flowers too and a lot of the bottom leaves have fallen off.
The plant came in a small pot and I've only watered it once in the three days that I've had it.
I was waiting for it to get acclimatized before moving it to a bigger pot, right now I keep it in a bright spot where it gets some early morning sunshine.