Water tuberous begonias when the top inch of soil feels dry, avoiding wetting the leaves whenever possible. Feed them every two to four weeks with a balanced liquid fertilizer to encourage abundant flowering. Remove faded blooms and damaged foliage regularly to keep the plant healthy and productive. Since the stems are somewhat brittle, provide support for taller varieties. As temperatures cool, reduce watering and allow the foliage to die back naturally before storing the dormant tubers.