Overwintering Begonias?

I live in a one bedroom flat and do not have room to bring in my begonia plants for the winter. I have a very small plastic covered frame I use as a greenhouse which is outside against my kitchen wall. My begonias are all in large pots and this is my first year with them. Can I leave them outside after pruning and cover them with bubble wrap or something like that to try and save them? Thank you.

By Gloria