Begonias are a perennial plant with soft, fleshy stems, and white, pink, red, orange or yellow flowers. There are 920 true species to the begonia family of plants. They are classified in three groups: tuberous, fibrous and rhizomatous. The plant originated in the tropical climates of Brazil and Mexico but all species are grown in the U.S. outdoors or in containers. Wax begonias, also called semperflorens, are very popular and easy to grow. Many begonias are grown for their large, attractive leaves and abundant cascading flowers.
Wax and Angel Wing Begonias
Wax begonias have small, glossy leaves and flower freely in pink, red, yellow, orange or white. They are grown as a perennial flower and can be used as annuals in colder climates. Prelude White and Prelude Bi-Color are both grown as annuals in colder climate zones.The flowers are 1/8 to 1/2 inch when open. Wax begonias thrive in a well-lit spot in winter. In the summer they prefer shade. Angel wing begonias are identified by their long, triangular-shaped leaves, some with a serrated edge. Peggy's Pet has dark green glossy leaves with bright white spots. Encanto Lana has a profusion of pink flowers blooming on a drooping stem.
Tuberous and Rex Begonias
Tuberous begonias grow particularly well in moderate to cool temperatures and high humidity. Spray with water frequently during hot weather. They have a winter dormancy period when their small tubers can be lifted out of the soil. In spring the tubers are replanted for the new growing season. Tuberous begonia flowers range from 1/2 inch to 4 inches across, very showy and ruffled. Rex begonias are grown primarily for their variegated leaves which have unusual color patterns. They require humidity over 50 percent and plenty of non-direct light. One of the oldest rex begonia cultivars is Abel Carriere, which was developed in 1878.
Wax begonias are very easy to propagate by taking a 3-inch cutting. The fleshy stem sends out thread-like roots within a week. Leaf cuttings are also used to propagate most kinds of begonias.Trailing-scandent types of begonias such as Ellen Dee and Shippy's Garland grow cascades of flowers that do very well in hanging baskets. Good light helps produce abundant flowers. Keep plants at temperatures between 58 and 72 degrees.
Pests and Disease
American begonias are easy to maintain and have few pests and disease problems. If mealybugs become a problem they can be removed by swabbing with household alcohol. Prevent problems by continual cleanup and grooming the dead leaves. Plants may become leggy by the end of the growing season and need the stems pinched back. Rex begonias are susceptible to mildew and botrytis, which looks like white dots on the leaves. Organic anti-fungal sprays are often recommended for this problem.
All varieties of American begonias can be grown in all USDA hardiness zones, according to the University of Florida. Begonia roots are fleshy and spread easily. The growing medium begonias prefer is loose and airy with good water retention. All begonias like potting soil that is rich in organic materials such as humus and sphagnum moss. When they are grown in organic nutrient-rich soil they need less fertilizing. As the growing season begins in spring, feed begonias with compost or a diluted compost tea. Feed again every two weeks until frost.