Dear Brian, In old gardening books I have often found the advice to divide Begonia tubers. Personally I would not do it. The risk of losing all the segments seems too big. If your Begonias have shoots of only a few cm tall right now I would wait a little longer until they have 2 or 3 leaves and are about 10cm tall. Then cut them off at their base, sometimes they have rootlets. In general these cuttings root well and produce a reasonable sized tuber. I have done this many times with little losses. I never lost a mother tuber this way. Even leaf cuttings are possible, I found an interesting article on this subject and tried last summer. The leaves rooted indeed but did not produce tubers big enough to survive the winter. I might have started too late in the season, though. What type of tuberous Begonia do you grow? Species or Hybrids? Greetings from spring.... Uli