Rex Begonia

How to care for Rex Begonia

Light

Rex begonias require bright, indirect light to maintain the intensity of their leaf colouration. An east or north-facing windowsill in the UK is often suitable, whilst a west or south-facing position should be screened from direct sun to prevent leaf scorch. Insufficient light causes the distinctive patterning to fade and leads to etiolated growth; however, exposure to harsh midday sun will quickly bleach and damage the delicate leaves.

Watering

Water thoroughly when the top 2-3 cm of compost feels dry to the touch, then allow excess to drain freely. Rex begonias are highly susceptible to root rot if left sitting in water or kept consistently moist. Water should be applied at the base of the plant or poured around the rim of the pot rather than over the foliage, as water sitting on leaves can cause fungal spotting and rot. Reduce watering frequency in autumn and winter when growth slows, but do not allow the compost to dry out completely.

Soil and potting

A light, free-draining compost is essential. A suitable mix can be made from two parts peat-free multipurpose compost, one part perlite, and one part fine bark or coir. Good aeration at the roots reduces the risk of root rot and encourages healthy rhizome development. Avoid heavy or water-retentive soils, and ensure the pot has adequate drainage holes.

Feeding

Feed every two to four weeks during spring and summer with a balanced liquid fertiliser diluted to half the recommended strength. A fertiliser with a slightly higher potassium content, such as a tomato feed, can encourage better leaf colouration. Feeding should be stopped or greatly reduced from October to February when the plant is in semi-dormancy and active growth has paused.

Humidity and temperature

Rex begonias thrive in humidity levels of 50-70% and are less tolerant of low humidity than many other houseplants. In centrally heated UK homes, humidity should be increased by grouping plants together, placing pots on a tray of damp pebbles, or using a room humidifier. Misting directly onto the leaves is not recommended as it promotes fungal disease. The ideal temperature range is 16-24 C; plants should not be exposed to temperatures below 13 C or sudden cold draughts, both of which can trigger leaf drop and dormancy.

Repotting

Repot in spring when roots begin to emerge from the drainage holes or the plant appears to have outgrown its container, typically every one to two years. Rex begonias have a relatively shallow root system and grow well in wide, shallow pots that accommodate the spreading rhizome. Move up only one pot size at a time, as excessively large containers hold too much moisture and increase the risk of root rot. Refresh the compost at repotting even if a larger pot is not required.

Pruning

Pruning is mainly carried out to remove dead, damaged, or dying leaves at the base of the stem, which helps improve air circulation and reduces the risk of fungal disease. Leggy or overgrown stems can be trimmed back in spring to encourage bushier growth from the rhizome. Always use clean, sharp scissors or a blade to avoid introducing infection. Some leaf loss in winter is normal and does not necessarily indicate a problem.

Is Rex Begonia toxic?

Common problems

How to propagate

Leaf-wedge or leaf-section cuttings

Cut a healthy, mature leaf into sections approximately 4-5 cm square, each containing a main vein. Press the sections lightly into the surface of a moist mix of perlite and coir, vein-side down, and enclose in a propagator or clear bag to maintain humidity. Plantlets should emerge from the cut veins within four to eight weeks at 20-22 C.

Petiole cuttings

Cut a healthy leaf along with its petiole (leaf stalk), trimming the petiole to around 4 cm. Insert the petiole into moist propagating compost at an angle and cover with a clear bag or propagator lid. Roots and a small plantlet should develop at the base of the petiole within several weeks.

Rhizome division

When repotting, the creeping rhizome can be divided into sections each bearing at least one growth point. Dust cut surfaces with powdered cinnamon or a fungicide, then pot each section separately into fresh compost. This method produces established plants more quickly than leaf cuttings.

Where Rex Begonia comes from

Native to Assam (north-eastern India), southern China, northern Vietnam.

Story and origins

The genus name Begonia was given by Charles Plumier in 1690 in honour of Michel Begon, a French colonial administrator and patron of botany who served as governor of Saint-Domingue (present-day Haiti) and facilitated early botanical exploration in the Caribbean. The species epithet rex is the Latin word for king, a reference to the commanding and ornate appearance of the foliage, which distinguished it markedly from other begonias known at the time of its formal description.

Begonia rex was formally introduced to Western horticulture in 1858 when a plant was collected from the Khasi Hills of Assam, north-east India, and received at Kew Gardens. Its extraordinary foliage caused immediate excitement among Victorian plant enthusiasts, and hybridisation began almost immediately. By the latter decades of the nineteenth century, the Rex Cultorum Group had been established through extensive crossing with other rhizomatous begonia species, producing the wide diversity of leaf patterns and colours available today. The plant became a symbol of Victorian horticultural ambition and remains one of the most widely cultivated ornamental foliage plants worldwide.

Varieties to know

Begonia rex 'Escargot'

One of the most recognisable cultivars, with leaves that curl into a tight spiral resembling a snail shell, marked in silver and green.

Begonia rex 'Fireworks'

Features deep purple leaves with bright silver markings and a striking, almost electric appearance; compact in habit.

Begonia rex 'Red Robin'

Displays rich burgundy-red leaves with silvery spotting; one of the more reliably compact and easy-to-grow cultivars.

Begonia rex 'Merry Christmas'

Has bold red centres with contrasting green margins and silver zones, evoking the colours of the festive season.

Begonia rex 'Silver Queen'

Large, predominantly silver leaves with narrow dark green margins; valued for its bright, light-reflective foliage.

Fun facts

• The leaves of Begonia rex can reach up to 30 cm in length in mature specimens grown under ideal conditions.
• The spiral leaf arrangement seen in cultivars such as 'Escargot' is caused by asymmetrical cell growth during leaf development, a trait that occurs naturally in the wild species.
• Begonia rex was first described scientifically in 1858 after a specimen was discovered growing on a limestone rock face in Assam and sent to the Royal Botanic Gardens at Kew.
• The genus Begonia, with over 2,000 recognised species, is one of the largest genera of flowering plants in the world.
• Rex begonias produce small, inconspicuous pink or white flowers but are almost always grown for their foliage; many growers remove flower spikes as they appear to redirect energy into leaf production.

Rex Begonia FAQ