Tuberous begonia

Sun

Partial shade or bright filtered light; gentle morning sun is suitable, but avoid hot afternoon sun.

Water

Keep evenly moist during active growth, allowing the surface to begin drying between waterings. Reduce watering as growth dies back and keep dormant tubers dry.

Soil

Humus-rich, freely draining soil or potting mix; slightly acidic to neutral. Avoid heavy, waterlogged ground.

Height

0.5-2 ft (0.15-0.6 m)

Spread

0.5-1.5 ft (0.15-0.45 m)

Flowers

Summer to autumn, until frost; white, yellow, orange, pink or red, often with contrasting edges. Flowers may be single, semi-double or double.

Foliage

Fleshy, asymmetrical leaves with toothed edges, usually green but sometimes bronze-tinted; foliage dies back for winter dormancy.

Growth

Moderate to fast during the growing season

Care needed

Medium

• Deer resistant
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Needs looking after

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.1 ft (0.33 m)

3. After 2 years

   1.2 ft (0.36 m)

4. After 3 years

   1.2 ft (0.38 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Fast

• Start tubers hollow side up in shallow trays of compost in a bright, frost-free place; cover lightly once shoots develop.
• Plant outdoors only after frost risk has passed and nights are reliably mild; harden off indoor-grown plants first.
• Water the compost rather than the leaves and flowers, and empty standing water from saucers.
• Feed container plants every two weeks with a balanced liquid fertiliser at the label rate while actively growing.
• Support heavy-flowered upright plants with short stakes inserted carefully away from the tuber.
• Before frost, lift tubers or bring pots under cover; let foliage die back, then store cleaned, dry tubers somewhere cool and frost-free.

Pruning. Remove faded flowers and damaged leaves throughout summer, cutting rather than pulling brittle stems. After the foliage has died back in autumn, remove the dry stems before storing the tubers.

Late winter

Check stored tubers and discard any that are soft or rotten.

Early spring

Start tubers indoors in shallow compost with gentle warmth and bright, indirect light.

Late spring

Harden off and plant outside after the last frost, once nights are mild.

Summer

Water regularly, feed container plants and support stems carrying heavy flowers.

Summer to early autumn

Remove faded flowers and check for mildew, aphids and stem rot.

Autumn

Reduce watering as leaves yellow; move plants under cover or lift tubers before frost.

Winter

Keep dormant tubers dry, cool and frost-free, checking occasionally for decay.

• Use upright forms in pots beside shaded entrances, where their flowers can be seen close up.
• Plant trailing forms in hanging baskets beneath a porch or lightly shaded pergola.
• Add seasonal colour to shaded borders in front of ferns and hostas, using raised or well-drained planting pockets.
• Combine pale pink or white flowers with silver-leaved foliage plants for a restrained courtyard display.

Garden styles it suits: Modern courtyard, Victorian, Cottage garden, Romantic rose garden, Pastel border and Small-space.

Plant it with: Ferns, Hostas, Fuchsias, Coleus, Impatiens and Silver falls dichondra.

Wildlife: Single flowers may attract some insects, but heavily double forms offer little accessible pollen or nectar. It is not a strong choice for a pollinator-focused planting.

• Powdery mildew: allow space for air circulation, avoid drought stress and remove badly affected leaves.
• Grey mould and stem or tuber rot: remove decaying flowers promptly, improve drainage and keep water off the crown; discard rotten tubers.
• Vine weevil: larvae can destroy roots and tubers, especially in pots; inspect rootballs and use an appropriate beneficial nematode treatment when soil temperatures suit the product.
• Leaf scorch and bud drop: protect from hot sun, drying winds and extreme heat, and avoid alternating drought with heavy watering.

Toxic to cats, dogs and horses if eaten, with the highest concentration of harmful soluble oxalates in the tubers and other underground parts. Ingestion can cause salivation, vomiting and more serious illness after substantial amounts; contact a veterinarian promptly. It can also be harmful to people if eaten, particularly the tubers; do not treat it as an edible plant.

• Wax begonia (Begonia Semperflorens Cultorum Group)

  Usually has smaller flowers, rounded glossy leaves and a compact, bushy habit; it has fibrous roots rather than a dormant storage tuber.

• Rieger begonia (Begonia × hiemalis)

  Often sold as a compact flowering houseplant with clusters of smaller, rose-like flowers; it is not normally managed through the same dry tuber dormancy.

• Bolivian begonia (Begonia boliviensis)

  Typically has narrower leaves and slender, hanging flowers with long, pointed petals rather than the broad, rounded blooms of most tuberous hybrids.

Begonia honours Michel Bégon, a French administrator and patron of botany, while tuberhybrida refers to the group's tuber-forming hybrid origin.

Propagation. Take basal shoot cuttings in spring, keeping them warm and humid but not waterlogged. Experienced growers can divide large tubers in spring, leaving a healthy bud on each section and allowing cut surfaces to dry before planting. Seed-grown plants are slower and may differ from the parent.

Accepted botanical name

Begonia tuberhybrida

Sources: GBIF (CC BY 4.0). The care and design notes are LandscapeGPT's own.