Posted: 07/08/2015 at 18:17
From what I've read, it is an annual and does not make a corm like other Begonia. That said, I've overwintered the bedding Begonia in the past because they were a gift and they came through and flowered well the following year. I'll be trying the same thing with mine, bring inside when the frost arrives or when it gets really cold and the plant does'nt produce more flowers.I cut them back so to reduce stress on the plant but leave about 10cm or so of stems. Watered sparsely over the winter and keep frost free with as much light as possible.
If anyone knows a better way then so much the better.