Lots of light and humidity are key to wintering over begonias.
Not a lot of blooms in the house right now, but this Dragon Wing Begonia is doing well this winter. This is my "annual" begonia, which is almost ten years old now. I bring it in each fall and put it out again in the spring. Mary gave this to me in 2002, and it was so beautiful that first fall I just couldn't leave it outside to die. Every spring I cut it back when I put it outside, and then again in the fall when I bring it in, and it just keeps flowering. The blooms are this pretty salmon pink in winter, and darken slightly in summer.
This video has absolutely nothing to do with my begonia, lol, but when I typed "Beguiling Begonia" for the headline, I was reminded of that Swing-era song by Cole Porter, Begin the Beguine. So for no other reason, enjoy Artie Shaw's band performing this classic dance tune! ("Beguine" is a type of West Indian dance similar to a Foxtrot)