I have never had success in overwintering tuberous begonias. Have already tried above suggestions and from numerous books. When left in the pot in a cool sunroom inside, there is nothing left but just soil in the spring. When left in a perforated bag in peat moss, they just become shriveled in the spring, whether in the basement or refrigerator. I have grown tuberous begonias successfully in spring, summer, and fall as well as from seed. It's too bad because they are not the easiest to grow from seed and I feel sad for my 'babies' when winter comes, feeling I will never see them again. What are professional growers and vendors not telling us on how they keep their tubers in storage big and PLUMP for sale? Please help. Thank you so very much, Mel
Overwintering Tuberous Begonias
Certified GKH Gardening Expert
There is a bit of work involved in getting plants into dormancy, then curing and then the correct cold temperatures for the winter months.
Here are some links that will give you more information.