Some have bicolor petals, such as white with a pink edge or yellow with a red edge. Begonias with petals that are edged in lighter or darker colors are called picotee. Buy dormant tubers in winter, either by mail from a specialty nursery or from a nursery or garden center. Another possibility is to buy blooming plants in summer. Most gardeners buy dormant tubers, which are easier to grow than seed and less expensive than blooming plants.
Tubers are also usually easier to find than blooming plants.
Although it's possible to find tubers in nurseries in regions where they grow successfully, the best selection is from specialty dealers. Most of their plants have been grown from seed strains carefully bred for high-quality flowers. Certain dealers also sell named varieties grown from stem cuttings, such as 'Avalanche', 'Bonfire' and 'Falstaff'. In this country, these tubers are available from White Flower Farm. Many gardeners shy away from tuberous begonias because of their reputation for being difficult to grow.