Sometimes I overwinter hot pepper plants, bring them indoors because although they are perennials, they can't tolerate freezing weather.
Almost 100% of the time, I can tell if they didn't survive the winter, because the stem has turned from green to brown. They usually die if I forget to water them often enough, or if they're in the garage where it can get below freezing if the outdoor weather is cold enough. I'm not putting a heater in the garage to try to change that, though I suppose it wouldn't eat up that much power if the heater had a good thermostat and I just set it to 36F or something and had it near the plants.
Last November, a few plants, instead of overwintering, I cut them at the base of the stem, and hung upside down in my garage. Unquestionably dying and dead within very few days, but this buys me time to harvest the peppers, opposed to the rest I pick as soon as it's a sure thing that the overnight temps will drop below freezing.
Same evening in November, I brought a live plant of similar type, into the garage in a pot, alive still. It was still alive till some cold days in Jan. made the garage below freezing then it died.
Its stems turned completely brown, yet the plants I have had cut and hanging since November, still have green stems ???????????
I've noticed this before, but never really thought about it. Why would a dead plant still in its soil, turn brown while those cut off, stay green? Of course I only mean the stems, the leaves withered to dry crunchiness within half a week, but they too, are still green.