Native to many tropical and subtropical regions worldwide. Begonias are grown for their colorful blooms and textured, multicolored foliage. Outdoors, most grow best in containers in filtered shade. In the ground, they need rich, fast-draining soil; consistent but light feeding; and enough water to keep soil moist but not soggy. Most thrive as indoor plants, in greenhouse, or under a lath. Almost all require at least moderate humidity. (In dry-summer areas or indoors during winter, set pots in saucers filled with wet pebbles.) Most begonias are easy to propagate from leaf, stem, or rhizome cuttings.
Of the many hundreds of species and selections, relatively few are sold widely.
Begonia enthusiasts group or classify the different kinds generally by growth habit, which coincidentally groups them by their care needs.
Cane-type begonias. They get their name from their stems, which are tall and woody, with prominent bamboo-like joints. The group includes so-called angel-wing begonias, named for their folded, often spotted or splotched leaves, which resemble wings.
Cane-type begonias have multiple stems, some reaching 5 ft. or more under the right conditions. Most bear profuse, large clusters of white, pink, orange, or red flowers from early spring through autumn. Some are everblooming. Among the many available selections are 'Bubbles', with spotted foliage and pink flowers with an apple-blossom fragrance; 'Honeysuckle', with plain green foliage and fragrant pink flowers; 'Irene Nuss', with dark red-and-green leaves and huge, drooping clusters of coral-pink flowers; and 'Orange Rubra', with medium green leaves, sometimes spotted with silver, and bright orange flowers.
When roots fill 4-in. pots, plants can be moved to larger containers or planted in the ground. Position plants where they will get plenty of light, some sun, and no wind. They may require staking. Protect them from heavy frosts. Old canes that have grown barren should be pruned to two leaf joints in early spring to stimulate new growth.
Dragon Wing begonias. A hybrid between angel-wing (cane-type) and wax begonias. Shiny green leaves form a foliage mass 11 ft. high and 1012 in. wide; bright red or pink flowers bloom from spring until frost. Excellent as bedding plants and in containers. Do best with morning sun and light afternoon shade; tend to burn in hot afternoon sun. In shade, plants have a more open habit and bloom less generously. Baby Wing begonias are about the same size but have smaller leaves; white or pink flowers appear earlier than those of Dragon Wing types.
Hardy begonias. Zones US, MS, LS, CS; USDA 6-9. Several begonias are hardy throughout the South, but B. grandis (called hardy begonia and sometimes offered as B. evansiana or B. grandis evansiana) is the best known. It grows from a tuber and reaches 23 ft. tall and wide, its branching red stems set with large, smooth, coppery green leaves with red undersides. Pink or white summer flowers are borne in drooping clusters. The plant multiplies readily by bulbils produced in leaf axils; it dies down after a frost. Likes moist, woodsy soil and light shade. Excellent companion for ferns, hostas, and hellebores. The Garden Angel series includes full, upright plants with small pink blooms and silvery, maplelike leaves highlighted in plum and pink shades; hardy to 0F. 'Heron's Pirouette' features exceptionally large clusters of hot pink flowers.
B. sinensis has much smaller leaves on a lower-growing plant (to 1 ft. tall and wide). It blooms from summer to fall. The species has pink flowers; 'Shaanxi White' bears pure white blooms.
B. sutherlandii is hardy from the Middle South (USDA 7) southward and grows 1 ft. tall, with wider spread; its weeping form makes it a good choice for hanging baskets and containers. Tooth-edged bright green leaves have red veins and margins. Clusters of creamy orange to bright tangerine blossoms appear in midsummer.
Hiemalis begonias. Usually sold as Rieger begonias. Bushy, compact, to 1012 in. tall and wide. Profuse bloomers and outstanding outdoor or indoor plants. Flowers average about 2 in. across and appear over a long season that includes winter in frost-free areas. On well-grown plants, green leaves and stems are all but invisible beneath a blanket of bloom. Give indoor plants plenty of light in winter. In summer, keep out of hot noonday sun. Water thoroughly when top inch of soil is dry. Don't mist leaves. Plants may get rangy, an indication of approaching dormancy; if they do, cut stems to 4-in. stubs.
Multiflora begonias. Bushy, compact plants grow to 11 ft. tall and wide. Abundant summer and fall blooms in carmine, scarlet, orange, yellow, apricot, salmon, and pink. Includes the Nonstop strain. All multifloras are essentially small-flowered, profuse-blooming tuberous begonias; for care, see Tuberous begonias.
Rex begonias. With their bold, multicolored leaves, these probably have the most striking foliage of all begonias. They grow 614 in. tall and wide. While many named selections are grown by collectors, easier-to-find unnamed seedling plants are almost as decorative. The leaves grow from a rhizome.
Give rex begonias bright light through a window, and water only when top inch of soil is dry. They also need high humidity (at least 50 percent) to do their best. In dry climates or indoors in winter, provide moisture in the air by misting plants with a spray bottle, placing pots on wet pebbles in a tray, or keeping plants in a greenhouse. When the rhizome grows too far past edge of pot for your taste, either repot into slightly larger container or cut off rhizome end inside pot edge. Old rhizome will branch and grow new leaves. Make rhizome cuttings of the piece you remove and root in mixture of half peat moss, half perlite.
Rhizomatous begonias. Like rex begonias, these grow from a rhizome. Although some have handsome flowers, they are grown primarily for foliage, which varies in color and texture among species and selections. The group includes so-called star begonias, named for their leaf shape. Rhizomatous begonias perform well as houseplants. Plant them in wide, shallow pots. Give them bright light through a window, and water only when the top inch or so of soil is dry. They flower from winter through summer, the season varying among specific plants. White to pink flowers appear in clusters on erect stems above the foliage. Rhizomes will grow over edge of pot, eventually forming a ball-shaped plant; if you wish, cut rhizomes back to pot. (For care of rhizomes, see Rex begonias.)
B. masoniana. IRON CROSS BEGONIA. Large puckered leaves; known for chocolate-brown pattern resembling Maltese cross on green background. Flowers are insignificant.
Shrublike begonias. This large class is marked by multiple stems that are soft and green rather than bamboo-like as in the cane-type group. Grown for both foliage and flowers. Leaves are very interesting. Some are heavily textured, others grow white or red hairs, and still others develop a soft, feltlike coating. Most begonias in this group grow upright and bushy, but others such as 'Bonita Shea' are less erect and make suitable subjects for hanging baskets. Flowers in shades of pink, red, white, and peach can come any time, depending on species or variety.
Outstanding examples include fern-leaf begonia (B. foliosa), with inch-long leaves packed tightly on a twiggy plant for a fernlike look. Its long, drooping stems (to 3 ft.) hold small white flowers nearly year-round in mild weather, or red shades. Fuchsia begonia (sold as B. fuchsioides or B. foliosa miniata) has delicate stems to 2 ft. tall, with dangling rose-pink to rose-red flowers that resemble fuchsias. The sturdy, sun- and wind-tolerant 'Richmondensis' can reach 2 ft. tall and 3 ft. wide, with arching red stems and shiny, deep green leaves with red undersides. Its vivid pink-to-crimson or white flowers develop from darker buds nearly year-round.
Care consists of repotting into larger containers as the plants outgrow their pots. Some shrublike begonias can get very largeas tall as 8 ft. They require ample moisture, but let soil begin to dry on surface between waterings. Prune to shape; pinch tips to encourage branching.
Trailing or climbing begonias. These have stems that trail or climb, depending on how you train them. They are suited to hanging basket culture or planting in the ground where well protected. Growing conditions are similar to those for tuberous begonias, though trailing types are not lifted. Sporadic bloom during warm weather.
Examples include hybrid 'Potpourri', with strongly scented deep pink flowers, and one of its parents, B. solananthera, with glossy, light green leaves and fragrant white flowers with red centers. B. glabra has trailing stems to 3 ft. long, with heart-shaped, bright green leaves and profuse white flowers in winter and spring.
Tuberous begonias. These magnificent large-flowered hybrids grow from tubers. They range from plants with saucer-size blooms and a few upright stems to multistemmed hanging basket types covered with small flowers. Except for some rare kinds, they bloom in summer and fall, in almost every color except blue.
Strains are sold as hanging or upright. The former bloom more profusely; the latter have larger flowers. Colors are white, red, pink, yellow, and peach; shapes are frilly (carnation), formal double (camellia), and tight-centered (rose). Some flower forms have petal edges in contrasting colors (picotee). Popular strains are Double Trumpet (improved rose form), Prima Donna (improved camellia form), and Hanging Sensation (camellia form). On Top series (camellia form) stands up well to high heat and humidity.
Grow tuberous begonias in filtered shade, such as under lath or in the open with eastern exposure. Tuberous begonias are best in the Upper South and Middle South (USDA 6-7); not suited to areas of extreme heat. In autumn, when leaves begin to yellow and wilt, reduce watering. When stems have fallen off the plants, lift tubers and shake off dirt; then dry tubers in sun for 3 days and store in a cool, dry place, such as a garage, until spring. When little pink growth buds appear, plant the tubers once again. You can also buy tubers from garden centers in spring.
B. boliviensis, to 1 ft. tall and 2 ft. wide, with narrow, pointed leaves and orange flowers, is a parent of many hybrids in the tuberous group. Look for 'Bertini', with deep orange-red blooms; 'Bonfire', with bright orange-red blooms; and 'Bellfire', with dark purple leaves and coral blooms. Heat-tolerant, long-lived 'Santa Cruz Sunset' has rich orange-red flowers.
Wax begonias. Dwarf and taller strains are grown in garden beds or containers as annuals; they bloom from spring through fall, producing lots of small (121 in.) flowers in a white through red range. Foliage can be green, red, bronze, or variegated. In mild climates, plants can over-winter and live for years. They thrive in full sun in the Upper South and Middle South (USDA 6-7); prefer filtered shade elsewhere, but dark-foliaged kinds will take sun if well watered. The popular bronze-leafed Cocktail series, to about 8 in. tall, includes 'Brandy' (light pink flowers), 'Gin' (rose-pink), 'Rum' (pink-edged white), 'Vodka' (scarlet), and 'Whiskey' (white). Super Olympia series is similar in size and flower-color range, but with green foliage. Party series, to 1 ft. tall, is early blooming and heat tolerant; available in green- and bronze-leaf forms. Stara series, 1620 in. tall, tolerates heat and drought; foliage changes from green to deep bronze as the season progresses.
Plants in the Big series (hybrids between wax and angel-wing begonias, sold as B. x benariensis) are vigorous, bushy, heavy-blooming plants to 20 in. tall and wide, with flowers up to 212 in. across. Combinations include red flower with green leaf, red with bronze leaf, and rose with bronze leaf. The Whopper series is even larger, to 36 in. tall and wide, with blooms up to 3 in. across. Available in red with green leaf, red with bronze leaf, and rose with green leaf.