I am no means an expert on cane begonias but they have quickly become one of my favorites. Of the three begonia types, there are thousands of begonias, hundreds or more of cane begonias. I'd say they like being on the dry side seeing how I lost a 3 ft. begonia to root rot. I got one of those pots that didn't have drainage holes and didn't notice!
I clipped it back and have been trying to root them. It was late in the season, and I might have been too late. Plus, had to bring them indoors. It looks like I may have 1 cutting to survive winter.
The original plant has one live-looking stem. So we'll see. It is easy enough to replace as they sell them all over. I just hate to see one of my favorites struggle. So. Not too much water, keep moist but not wet. I use a blooming fertilizer starting in the spring, but being an indoor plant, they can bloom year around so I like a time-released fertilizer like Osmocote.
Cane begonia can grow to 6-7 feet tall! If you don't want it to grow tall, just cut it back in half. You can root the healthy cuttings easy enough. They like shade or morning sun. Or a bright window in your home. Mine can grow outdoors and take the heat in our tropical summers but they do come in in the winter. While some are grown for their leaf patterns, others are grown for their exciting bunches of flowers.