Begonia (Tuberosa Group)

Begoniaceae is a large, flowering plant family, the name of which honors Michael Begon (1638-1710), Governor of French Canada, and includes about 1500 different species and hundreds of hybrids. Mature begonia plants range in size from a few inches high to over 12 inches high, and the flowers, foliage colors, and sizes are very diverse.

The American Begonia Society has created a number of non-scientific categories for classifying Begonias including tuberosa. Begonia (Tuberosa Group) hybrids have shown some cold hardiness including the tuberous Begonia grandis (USDA zones 6-10). The typical form has large round leaves with a pale green reverse, or with red veins, and pale pink or white flowers and come up in spring from a dormant tuber to flower in late summer. As winter approaches, small tubers or bulbils develop at each leaf axis; these drop and will sprout the following year, in time resulting in a lovely patch of begonias.

Begonia (Tuberosa group) is a hybrid tuberous begonia encompassing 13 different types of summer flowering tender plants with colorful waxy petals.  Flower shapes vary from camellia-like or carnation and differ in the number of petals (single, double), petal type (banded, ruffled)  or habit (compact, weeping, cascading).  Some hybrids may need staking.  Tuberous Begonias prefer dappled sunlight or bright shade in organically rich well-drained moist, but not soggy soil, full sun, or full shade.  While tricky to grow, they make excellent interior or exterior container plants, mass planted in border fronts or in window boxes.  Plant tubers shallowly n groups of 3-4 per container or space 12"-18" apart in the ground.  Outdoor containers can be brought inside to overwinter.  Plants do not like humidity or heat so can sometimes suffer in southern summers.  Protect from too much sun and wind with mulch and protected siting, but make sure to provide good air circulation to avoid foliar diseases.  Begonias propagate very easily from stem or leaf cuttings.

Regular fertilization during the growing period produces the most profuse bloom. Start plants indoors in late winter about 2 1/2 to 3 months before all threat of frost is over. Plant tubers shallowly with concave side up. Taper off watering in fall when leaves begin to turn yellow. Before first fall frost, store containers in frost free location or dig up tubers and store. Store until time to replant in late winter in preparation for the next growing season.

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 problems. 

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