I'm terrible about watering plants inside, all of my potted plants have to be pretty tough to survive living in my house! Add in the fact that most of our windows have overhangs that don't allow much sunlight in and overwintering inside isn't a viable solution for most tender perennials. I did find a way to keep some special (to me, anyway) plants, though. I really love Salvia Black and Blue but it's an annual here in Colorado. After doing some research I came across a method that allows me to keep it semi-alive through the winter. After a couple of frosts when all of the plant above ground is dead but before the ground freezes, I dig up the salvia and remove most of the dirt. I wrap the roots in damp newspaper and put them in a plastic shopping bag and knot it loosely. I hang the bags against an outer wall in my garage, just have to check them once or twice during the winter to make sure they don't dry out completely. They get planted out with the rest of the annuals in the spring, no worse for their winter treatment, and the plants are huge compared to the tiny seedlings I would've bought if I had to replace them.
