Begonia

Prepared by Karen Russ, HGIC Horticulture Specialist, and Al Pertuit, Extension Floriculture Specialist, Clemson University. (New 3/99. Revised 09/07 by Karen Russ. Images added 09/07.)

HGIC 1159

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For beautiful foliage and a constant display of color throughout the season, grow begonias.

Height/Spread

Most begonias that we grow outside will be between 8 inches and 2 feet tall.

Ornamental Features

Begonias are grown for their foliage and/or for their attractive flowers. Begonias flower throughout the summer and up to the first frost. They can be used as bedding plants, in window boxes and in baskets and other containers.

Problems

Disease problems associated with begonias include Botrytis blight and stem rot, powdery mildew, and Pythium root and stem rot. The major pests of begonias are mealy bugs, spider mites, scales, snails and slugs.

Landscape Use

Begonias will not grow out of bounds and are ideal for small flowerbeds. Plants should be placed 12 inches apart for the best effect in the garden and somewhat closer in containers. Begonias look best when used in mass.

Most begonias grow well in partial shade and in a moist, well-drained soil with plenty of organic matter. In general, begonias need bright light to flower well. Some will burn if the light is too intense. Bronze-leaved wax begonias grow better with full sun than other types.

Begonias are not "heavy feeders," so fertilizer should be applied in moderation.

Species and Cultivars

The most common types of begonias for growing outside are the fibrous rooted begonias (or wax begonias) and tuberous begonias. These are tender in South Carolina, but the beautiful and perennial hardy begonia will grow throughout the state.

'Pizzazz White' Wax Begonia
Karen Russ, ©2007 HGIC, Clemson Extension

Wax Begonias (Begonia x semperflorens-cultorum): Few other annuals can beat the wax begonias for hardiness and continuous flowering throughout the summer. These begonias are not restricted to a partial shade; they can be grown in full sun as well. Wax begonias with bronze foliage do better in the sun than green varieties. Wax begonias withstand drought and heat better than other begonias, although they definitely prefer moist, well-drained, fertile soil.

Bushy plants, with shiny heart-shaped leaves of green, bronze-red or mahogany are covered with small white, pink, rose or red flowers.

Set plants 6 to 8 inches apart in the garden after the danger of frost is past. Plants may also be started indoors from stem cuttings taken in the spring or fall.

Cultivars

• 'Victory' is a series with bronze leaves. They grow 8 to 10 inches in the garden and sport large, showy flowers.
• 'Challenger' comes in a mixture, where the red, rose, pink or white flowers contrast with its green-and-bronze foliage.
• 'Ambassador' series has large flowers on compact, green-leafed plants.
• 'Cocktail' series is 6 to 8 inches tall with bronze foliage. The flower colors are 'Brandy' (pink), 'Gin' (rose-pink), 'Rum' (white with a rose red edge), 'Vodka' (flowers) and 'Whiskey' (white).
• 'Prelude Series' hold up well through rain and heat. The compact plants have bright green foliage.
• 'Pizzazz Series' includes white, red, and pink cultivars. They are heavy blooming and grow 8 to 10 inches tall.

Dragon Wings Begonia (Begonia x argenteoguttata 'Dragon Wings'): This begonia is known for its long blooming period - from spring through until frost without pause. It reblooms reliably because it is sterile and does not expend energy on producing seeds. The plant grows 2 to 3 feet tall, with tall arching canes and 5 inch long, glossy, deep green leaves. It will grow well in either sun or shade, and prefers fertile, moist but well-drained organic soil.

'Dragon Wings' Begonia in part shade
Joey Williamson, ©2007 HGIC, Clemson Extension

Hardy Begonia (B. evansiana syn. B. grandis): This is a superb southern heirloom perennial that is passed from gardener to gardener. They grow best with rich, moist soils in partial shade.

The hardy begonia reaches 2 to 3 feet in height. Small, pink flowers bloom in drooping clusters above the leaves in late summer. The large angel wing-shaped leaves are backed in glowing red. They are especially lovely when planted where late, low afternoon sun will shine through the leaves. Tiny bulb-like tubers that appear at the leaf joints in late summer can be used to increase your stock or to share with a neighbor.

Hardy Begonia is known for its beautiful foliage.
Karen Russ, ©2007 HGIC, Clemson Extension

Tuberous Begonias (B. x tuberhybrida): Tuberous begonias grow best in partial shade. The plants need frequent watering and light fertilization, but excess of either causes flower bud drop. Tuberous begonias will grow best in the upper Piedmont and mountain areas of South Carolina. They do poorly in very hot and humid parts of the state.

Tuberous begonias have 2-to 4-inch wide flowers in white, yellow, orange, rose, red and pink. They are available either in upright varieties or with trailing stems 12 to 18 inches long. The trailing types are nice to plant in hanging baskets.

Remove the first flower buds that appear so that the strength goes into the young plant. Remove the single female flowers before seed forms to keep the plant blooming. The female flowers are smaller and are on either side of the showy, double male flowers.

Tuberous begonias must be dug up and replanted each year because they will not survive winter cold. Dig tubers before frost. Cut tops back to within a couple inches of the tubers. After drying, pack the tubers in cardboard boxes between layers of vermiculite, peat moss, or wood shavings and store at 45 to 55 °F.

Start tuberous begonias in early spring by setting tubers into shallow flats. Keep out of direct sunlight. When the roots are established and shoots are about 1 or 2 inches high, move them to pots 4 to 6 inches wide. When all danger of frost has passed, move them outdoors.

'Non-stop Mocca Orange' Tuberous Begonia
Karen Russ, ©2007 HGIC, Clemson Extension

Cultivars

• 'Non-stop Series' are compact and small- flowered multiflora types. They are more heat-tolerant than other tuberous begonias and will flower longer. This type is best suited to growing in the South.

Rex Begonias (B. rex): Rex begonias are not grown for their flowers, but for their beautiful leaves. The leaves can be a kaleidoscope of colors - green, red, pink, silver, gray, lavender and a maroon, so deep that it appears black. These spectacular begonias grow best in part-shade in rich, moist, well-drained soil. They grow well in hanging baskets and other containers.

Cultivars

• 'Merry Christmas' grows 10 to 12 inches tall with smooth red and green leaves shaped like lopsided hearts.
• 'Silver Sweet' is an especially easy-to-grow 12 to 18 inch tall cultivar. Its leaves are like those of 'Merry Christmas' but are silver with green veins.
• 'Helen Teupel' grows to 12 inches tall with pointed, sharply lobed leaves that are purplish red brushed with pink and silver.

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