Are you referring to the large begonia of which there are many ( good reference Logee's Greenhouse, Danielson,Conn ) logee-info@logees.com.I have large angelwing silver spotted begonia and am preparing to bring them in in the next two weeks. Water them good, prune away any overgrown branches, and mine do fine in a northern window with a grow light. They a pretty tough I've found. If you are speaking about the small annuals they really do not do good in the house except perhaps if one has a greenhouse room or Florida room.

I live in 8A and I have a begonia on my covered front porch that did not freeze last winter.

galcho
I too live in Washington State. I live in the foothills of Enumclaw.I also grow Begonias,and my most favorites are the Tuberous.The way I overwinter mine here is that before first frost,when they get real leggy,I cut them off real close to the bulb. Only the bulb remains,and I dry them outside or in my greenhouse in for several days until they dry out real good.Then I put them in brown paper luch sacks in savings or sawdust and lable the bags of what colors they are Hanging or Non-Hanging and let them be until early spring.I have tried cutting them down and leaving them potted or in baskets but to NO avail.I've done this for the last 12 years and have only lost (1) bulb...because it was not dried out well enough so it rotted.Let them go dormant and keep them cool but do not let them freeze:) ***Suzanne