I agree with everyone else on the cold killing the mother tuber. Up here in Buffalo, NY I had a nice sized 24" pot that started out with one tuber and multiplied through the summer and I wound up with a very large pot full. Usually I would leave the plants outside until a good hard frost killed the leaves back at which time I would hack off the tops and store it. Unfortunately it rained the day before and I took the pot into the basement wet, by the time spring came, just about all the tubers were rotting. I did manage to save a few thankfully. Fortunately I didn't have any problems with my Alocasias since they never stay out when it's going to freeze.
