I had a beautiful beefsteak begonia that I divided and repotted last summer. It seemed happy at first, but all winter long it consistantly drops it's new growth. The dropped leaves are in perfect condition, and there is no sign of pests. I water properly, and the plant has been in the same location for over 10 years with never an issue. I had this same problem with an angelwing begonia last year, and I have not been able to find any information. Any theories welcomed!