We used to have thousands of begonias but no tuberous. They are a bit more difficult to carry over through the winter than the cane type we mostly had. There is a begonia forum on GW that may be helpful.

Here is a link that might be useful: Begonias

I once bought four bulbs and shared one with a friend. Mine were planted in separate pots and had growth but never grew to any size and certainly never had a bloom. My friend had great success, Who knows?

You can easy put up to 3 plants in a 12" pot. They like modified sunlight, like under a tree or some shade. They will actually look sun-burned if they get too much on a hot day.

They like a lot of water. And they will bloom like crazy. They need some fertilizer about mid-summer.