While begonias remain among the easiest of plants to propagate and maintain, the number of available forms and cultivars has increased so dramatically in the past quarter-century that common no longer applies.
A new generation of gardeners is discovering the versatility of these tropical natives, whose species number about 1,300, with more discovered and hybridized every year. By contrast, a mere 100 or so species were known in the 17th century, when monk and botanist Charles Plumier named the plants in honor of Michel Bigon, governor of Santo Domingo, who had introduced the grateful Plumier to Louis XIV.
In 1865, begonias became major players in the conservatories of the wealthy and powerful when botanist Richard Pearce returned from the Andes mountains in South America, bringing with him the parent of today's tuberous types.
The current undisputed queens of hanging baskets, these showy summer and fall performers include the aptly named camellia type, with 10-inch single and double blossoms in hues from ivory to cerise. The carnation, or fimbriata type, offers fringed blossoms on plants 12 to 18 inches tall. Of similar stature are Picotee begonias, in bicolored blends of apricot and yellow, pink and white, and reverse of both these combinations. Cascade begonias in soft pastels make ideal candidates for free-standing planters, window boxes and baskets.
All tuberous begonias flourish in partial shade, provided soil is well drained (overwatered plants are quick to rot) and temperatures do not consistently hover above 90 degrees. Most sun tolerant are multifloras, bushy plants about a foot tall that bear flowers somewhat smaller than other forms.
To preserve tubers, allow them to go dormant by withholding water, then remove all stems and foliage. Store tubers dahlia-style, in sawdust or dry peat, before potting them up again in early March. Young plants can be nurtured indoors, allowing plenty of time for strong root systems to develop, then gradually acclimate the begonias to outdoor conditions.
Also suitable for outdoor container gardens as well as the front of borders are wax or semperflorens begonias. These fibrous-rooted hybrids boast a compact habit with small, fleshy leaves and nonstop flowers in shades from rose to ruby. Contrasting button-shaped centers give the inch-wide blooms a perky appearance. 'Curly Locks,' for example, bears candy-pink flowers accented by a sulfur-yellow eye. In general, wax begonias require more sun than do their tuberous cousins. Pinching out the tops will encourage bushy growth and larger flowers.
While many gardeners treat wax begonias as annuals, they are tender perennials suited to indoor culture. Plants enjoyed outdoors in summer can be potted and brought indoors to adorn winter tabletops (specimens are best moved before the chance of frost, in order to give them plenty of time to adjust to their new surroundings).
When potting up plants for their winter hiatus, top off the plant to about 6 to 10 inches from the soil level--and prune roots so that the begonia fits comfortably and securely in its new container.