Flowers

How to Plant, Grow, and Care for Tuberous Begonias

Tuberous begonias have scrumptious blooms in rich hues, from pastel to bold. Their leaves add interest and contrast with unique shapes and deep shades. Enliven the shade collection with these floriferous tropicals, just in time for spring planting.

Tuberous begonias are....

standouts among the group with decadent blooms in vibrant colors. Laden with flowers, they bloom from late spring through frost to brighten shady zones. Lightly fragrant, their full flowers delight the senses and draw pollinators.

With pendulous blooms and forms that trail, they’re ideal in hanging baskets, window boxes, and pots. Upright and standard selections make a striking border planting and filler feature in container arrangements. Distinct leaf colors and forms among varieties heighten visual interest and add surprise among shade-loving plants.
What Are Tuberous Begonias?

Tuberous begonias are a class of begonias native to tropical regions of South America and southern Africa. In frost-free USDA zones 9-11, they grow outside all year, and in cooler zones, they perform as annuals or overwinter by storing their tubers. They rose to popularity in the 1850s Victorian era for their large, luscious blooms and conservatory-worthy features.

When the floriferous tropicals begin blooming, they flower continuously for up to four months or until temperatures drop. They prefer climates with mild summers and suffer in high heat and intense sun. In southern climates, treat them as spring annuals for a scrumptious display and early pollinator attractor.

Tuberous selections bridge the transition from winter to spring beautifully in the South and make a pleasing spring welcome. As temperatures rise, try placing them in the coolest shade spot available. In more northern climates, they flower with spring’s warmth and go through fall’s frost.

As with other begonias, their long bloom time and ability to flower in shade are unique qualities. Pair them with the dynamic foliage of caladiums, coleus, heuchera, hosta, and ferns. Impatiens and fuschia make lovely blooming counterparts.

Characteristics
The substantial blooms on tuberous varieties are single, double, or ruffled and often appear in pairs or clusters of three. From sunset apricot to blush pink, orange, red, white, and bicolors, the spectrum of hues brings a glow to shady garden spots or patio plantings. Many are picotee, where a delicate edge contrasts the main petal color. The fully-petaled flowers can reach six inches across and set them apart from other begonia classes.

It’s their tuberous roots, though, that define the group. The American Begonia Society divides the genus into informal categories, including fibrous-rooted, rhizomatic, and tuberous. Due to 1800-plus species and hybrids, distinct grouping is a challenge. The tuberous class has fleshy, starchy, modified stems that form root-like structures. Roots and shoots grow from the same bud (like a potato). The Tuberosa Group is then further classed based on form (standard, trailing) and flower (rose, carnation, camellia).

Foliage is dynamic, often serrated and pointed, and in deep green to mahogany, depending on the variety. Some have striking leaf patterns, and forms vary between trailing, upright, and standard.

Tuberous begonias are monoecious, meaning each plant contains both male and female flowers. In clusters, the male is the prominent bloom, often larger and with more petals. The female flowers are smaller, and some gardeners remove the female blooms to direct energy to the larger male ones for display purposes.

Native Area
Parent tubers to today’s hybrids came from tropical Bolivia, Peru, and the lower Andes Mountains, as well as tropical zones in southern Africa. Their natural growing conditions experience mild temperatures, humidity, organically rich soils, and regular moisture accompanied by periods of drying out. They enter dormancy in cool months, where tubers store moisture and nutrients for the growing season.

Planting
Plant the tropical beauties in containers, hanging baskets, window boxes, and beds in bright shade, where you’ll enjoy their added color and texture. They’re available as potted specimens from nurseries in early spring and also grow from tubers.

Plan for air circulation between plants to prevent fungal issues, usually with a spacing of 8 to 12 inches, depending on the variety. Shelter them from winds, which can break stems, and provide protection from afternoon sun.