Gypsy & Onewish, you're painting a picture of a plant with quite a wide range of tolerances - looks like I could try overwintering potted plectranthus in our cellar, which has some light and stays around 50-55*F throughout winter. I'm certainly going to try it next winter - thank you.
Chelle, oops - maybe you and I crossed oinks when wildflowers offered seeds to our swap - this is going to be a well loved plant.
Some years, in fall when most flowers have stopped, Plectranthus argentatus will put out long, thin wands covered with zillions of tiny flowers in our garden - the whole effect is of an ice blue cloud - and it brings a very-hard-to-find silver in our shady moonflower garden. Plus, occasionally in a mild winter here in zone 7, it has successfully overwintered outdoors in the ground. It will be interesting to see how Plectranthus barbatus compares to that.
