Non Stop Begonias ARE tuberous begonias - simply a variety name, much like "Kleenex" is a brand of tissue. They are bred specifically by a German breeding company, Ernst Benary. They are an annual, however you can dig the tubers.

Hmmm - thats odd.

I've bought nothing BUT non stop begonias for years and they have come back every year and I NEVER touch them. They are as perennial as any of my dahlias or roses.

Tuberous begonias can't take a freeze so are perennial in zone 9 if I am lucky. They may make it in zone 8 through a warm winter or in a warmer spot in your yard. I have a few in fern pots that I winter threw out side. I have many more that I let dry out and store in my closet each winter. My winter is rain and light freezes usually so rot is more of a concern.

David - the fact that you are in SF would explain why they are perennial for you