If it has a good enough root system it will probably come back. I would bring it inside, but don't expect the stem and leaves to recover. Temperatures in the 50s aren't cold enough to kill it if it is well-rooted. I have no personal experience with this plant but my salvia elegans and coccinea survived until the first hard frost, and even then the elegans was trying to come back from the roots. But they weren't babies at the time.

Thanks for the hope. I had no illusions about the stem or leaves coming back-- they're even farther gone now than they are in the photo. It is inside and in a humidity dome.

My S. divinorum survived a night below freezing in a pot in the greenhouse. Normally, the greenhouse is kept in the 50's, but had a heater failure.

Stems and leaves turned black, so I cut them off to the soil surface. It has now re-sprouted and has mutiple stems instead of one.

I'm wondering if routinely cutting this plant back hard each winter (before growth resumes in spring) might be a good idea.

I've successfully over-wintered this plant before, and been rewarded by beautiful flowers.