Gardening 101: Tuberous Begonias

Tuberous Begonia, Begonia × tuberhybrida

Tuberous begonias go in and out of fashion, depending on our collective appetite for blowsy blooms in attention-grabbing shades of red, orange, pink, and apricot. While there are some lovely, ruffled white varieties, when I think of tuberous begonias, I think mainly of crayon colors.

Begonias are tropical plants, grown in cooler climates primarily as container plants or flowering annuals in the garden, tuberous begonia can perk up a shady spot (direct sunlight will burn them) with its handsome, textured leaves (most begonias are succulents). Depending on the cultivar, tuberous begonias may look like small, bushy shrubs, covered bright flowers, or can grow like a trailing vine over the edge of a hanging planter.

Today’s vivid specimens with showy flowers are hybrids, descended from begonias that Victorian botanist Richard Pearce collected in the South American Andes in the 1986s. He found B. boliviensis, B. veitchii, and B. pearcei, which European hybridizers crossed to create a dizzying array of varieties–with frilly petals, ruffled petals, picotee petals, double petals, single petals–as well as a group of camellia lookalikes.

Is there a tuberous begonia for you? Sure sounds like it, doesn’t it? Read on to find out for sure:

Photography by Sara Barrett, except where noted.

What are tuberous begonias? With 1,923 species (most of which are succulents) in the Begonia genus, the varieties can be divided into three different categories based on their root systems: tuberous, fibrous, and rhizomatous.

Here’s how to tell begonias apart. Tuberous begonias, like potatoes, grow from bulbous parts. “You usually can tell a tuberous begonia because of a swollen structure at the base of the stems, underground or at soil level. This is the tuber (or sometimes it is a bulb), whose function is to store water and nutrients during dormancy so the plant can start anew,” notes The Begonian, a publication of the American Begonia Association. Rhizomes, also are underground stems, spread by creeping out sideways. Fibrous root systems spread out like a mat around the base of a plant.

How to propagate tuberous begonias is a question often asked by gardeners who have fallen in love with the ruffled flowers of a favorite potted plant. The short answer: it’s easy to propagate tuberous begonias. The best way to do it is from cuttings–and either stem or leaf cuttings will work. If you’re wondering how to grow tuberous begonias from cuttings, see step-by-step instructions at Propagation Tips by the American Begonia Society.

To grow tuberous begonias, you can plant tubers (they can be potted in March) or you can wait until the weather warms up and then buy potted plants from a plant nursery. For tips to plant tubers, see White Flower Farm’s How to Grow Tuberous Begonias video.

Where to Buy Tuberous Begonias

One reason to buy tubers is you will find a greater selection available by mail order than in plant nursery. In the UK, in addition to Blackmore & Langdon’s (which has been breeding begonias since 1901), you can find a good selection of tuberous begonia tubers at Thompson & Morgan and Crocus.

For US gardens, sources for begonia tubers include Longfield Gardens, Eden Brothers, and American Meadows.

Cheat Sheet

• Tuberous begonias are showy container plants; flank an entryway with pots planted with begonias that complement the paint color of a front door.
• If tuberous begonias get leggy or spindly, cut them back to a height of 3 inches to encourage new, bushier growth.
• Tuberous begonias need sun protection; find a shady spot for them where their flowers can glow.
• Flower size can vary, fro, 2 to 8 inches, depending on the variety.

Keep It Alive

• Remember that tuberous begonias are tropical plants and will balk at cold weather; don’t leave them outdoors overnight when temperatures dip below 50 degrees.
• Begonias are heavy feeders; fertilize weekly to encourage flower production.
• Tuberous begonias require well-drained soil and regular watering. (If the top inch of soil is dry, it’s time to water a potted tuberous begonia.
• Humidity and bright shade will make a tuberous begonia very happy.

Read more growing tips in Begonias 101: A Field Guide to Planting, Care & Design in our curated guides to Tropical Plants 101. For more ideas for colorful container planting schemes, see:

• Container Gardening: Sarah Raven’s 7 Tips for Perfect Flower Pots
• Gardening 101: Petunias
• Container Gardening: A DIY Planter on Wheels
• Fuchsia: A Field Guide to Planting, Care & Design
• Container Gardens: 5 Tips for a Perfect Window Box