On July 11, 2009 I converted some "hurt" begonias from a sale bin at the supermarket to hydroculture as an experiment. I wanted to learn about rooting them from stem cuttings, but the flowers were too pretty to discard, so I was going to wait until they stopped blooming.
They haven't stopped blooming, so the rest of the experiment will have to wait. Clearly, it is possible to grow happy begonias using passive hydroponic methods.