Fertilization is necessary for the plants to maintain double flowers. If flowers begin to become single, fertilize using a well-balanced fertilizer. Be sure to follow package directions.
Tuberous Begonias form tubers and these tubers can be stored for replanting in the spring. To dig and store tubers follow these directions. First, before frost kills the top of the plant, cut back the stems and dig the tubers. Wash off any soil and then allow the tubers to dry. Wrap dry tubers in newspapers or pack them in peat moss. Label each tuber or group of tubers so you know what they are come spring. Store the tubers in a dark, cool (35 to 45 F) place. Do not allow tubers to freeze.