Prized for their green foliage and many blooms, tuberous begonias are a tender perennial. Tuberous begonia foliage dies off each winter, but the underground tubers they grow from remain viable. They do not survive in frozen winter ground, so must be dug up and stored in order to winter over. The begonias go dormant over winter, requiring little care during storage. When properly stored, they are simple to replant in the bed or container in the spring, where they will once again bloom throughout summer and into fall.
Stop fertilizing the begonias in late summer. Gradually reduce watering until the first fall frost.
Cut off the tops of the begonia plants once they begin to yellow and die back in the fall. Cut off all but 5 inches of stem using garden shears or a sharp knife.
Dig around the tuberous roots to a 6-inch depth. Slip the trowel under the roots and lift the begonias out of the ground. Brush off the excess soil from the root system using your hands.
Lay down sheets of newspaper in a dry room. Spread the tuberous roots out to dry on the newspaper, ensuring that they are not in direct sunlight. Dry the begonias for one to two weeks or until the remaining stems become brittle and loose. Pull off the dried stems and brush off any small roots that are still attached to the tubers.
Fill a box with dry vermiculite. Set the tubers in the box and store them in a dry, cool room until you are ready to replant them in spring.