Begonia – Tuberous Types

This informal group of begonia species and hybrids includes the tuberous perennials that are native to the tropics of South America. They are best known for their showy and spectacular flowers and are a member of the Begonia family (Begoniaceae). Most of the varieties available at a nursery or garden center are hybrids. They may be grown as annuals, herbaceous perennials or houseplants. This plant has a bushy, weeping or cascading habit and can grow 1 to 2 feet tall and equally as wide. The glossy foliage is available in various shades of green with touches of red or bronze. The flowers appear in various forms, shapes and colors. They measure 3 inches across, may be single or double blooms, ruffled or serrated and come in many colors including white, pink, red, orange and yellow. Other forms available include bicolor, camellia and rose. Some cultivars have flowers that are classified as picotee, which means the petal edge is a different color than the main portion of the petal. They usually flower for 4 months, from early summer until the first frost. 

Begonias of this type prefer partial shade to dappled shade and organically rich, moist, well-drained soil. They can tolerate early morning sun and late afternoon sun. They are not drought tolerant. This plant is hardy in USDA zones 9 to 11. Avoid overcrowding since they require good air circulation to prevent foliar diseases. This plant does not like humidity or heat; therefore, they can sometimes suffer in southern summers.  Protect them from too much sun and wind. Regular fertilization during the growing period produces the most profuse blooms. Remove spent flowers and leaves. If staking is needed, avoid injuring the tuber. Taper off watering in fall when the leaves begin to turn yellow. Begonias propagate very easily from seed and root cuttings

For outdoor plantings, the tubers may be taken up and stored in a dry place over the winter. Before the first fall frost, store the plant containers in a frost-free location or dig up tubers and store. Store them until time to replant in late winter in preparation for the next growing season. Start plants indoors in late winter about 2.5 to 3 months before all threats of frost are over. They may be re-planted outdoors or the containers may be brought outside after the last frost. Plant the tubers shallowly in groups of 3 to 4 per container or space 12-18 inches apart in the ground. Plant the tubers shallowly with the concave side up.

While tricky to grow, they make excellent interior or exterior container plants, mass planted in border fronts or in window boxes.    

Insects, Diseases, and Other Plant Problems: Aphids, mealybugs, whiteflies, slugs, and snails are occasional problems. Powdery mildew and stem rot can occasionally occur. Too much water can cause tuber rot and not enough air circulation can cause disease. 

VIDEO Created by Elisabeth Meyer for "Annuals, Perennials, Vines, and Groundcovers" a plant identification course offered in partnership with Longwood Gardens. 

More information on Begonia.