As a comment about Rose-Scented Geranium (Pelargonium capitatum)
I'm overwintering this plant in the basement right now, having received it in trade this summer. It's raised off the cold floor and under a plant light, but it's probably not much warmer than 50 degrees in the basement, often closer to 40.
When I brought it in, it had grown so much I'd had to cut it back just to make it easier to handle. It has since regrown to the size it was in the ground without being watered more than twice all winter.
Although I've not seen any blooms I literally don't care whether I ever do. Its velvety, ruffled leaves smell just like a citrusy rose to me.