This might not sound like a problem to some of you, but my Dragon Wing Begonias have gotten way too big and I don't know what to do.

I have five deck-rail planters with these beautiful begonias. But they've gotten so tall and top-heavy that with the heavy rains we've been having here in PA recently, two of the planters have fallen off the railing onto the deck, and many stems broke off as a result. In fact, one of the boxes lost so much of the plants, it couldn't be salvaged.

So I'm wondering, can these plants be pruned? And if so, what's the best way to do that? If not, is there something else I can do to prevent them from falling over? Thanks!