I'm a huge fan of Salvia guaranitica 'Black and Blue' -- actually, I think everyone is. Dark blue flowers, contrasting black calxy -- it is a supermodel of a plant. And, for me, tender. But: I learned something: It produces tubers. So, after our recent freeze, I went out with a garden fork and popped the plants. Sure enough, nice, fat, funny looking tubers. They've now been wrapped loosely in news paper, popped in a plastic grocery bag, and are sitting in the basement to wait for spring. (BTW: I used to avoid tender bulbs like dahlia and gladiolus because gardening books I'd read talked of storing them over the winter in damp but not wet sand (?) and such nonsense. But I've found a sheet of newspaper, a loosely closed plastic bad and cool basement work perfect.) Sure beats re-buying them every year!