I have a dark-leaved rex begonia - a pretty vigorous grower - that is crowding itself out of the pot I put it in last year. It has 3 distinct crowns, all along the outside rim of the pot. Is it possible to separate the crowns and replant them in individual pots? Is there a special technique or special care required? Of the 4 that I've had, this one is the most care-free and I would hate to damage it through ignorance. Many thanks for any advice.