Identity & taxonomy
- Scientific name
- Begonia rex Putz.
- Family
- Begoniaceae
- Genus
- Begonia
- Order
- Cucurbitales
- IUCN status
- Least Concern (LC)
- Wikidata
- Q2893850
- Begonia rex-cultorum (the trade name covering rex × hybrids)
- Rex begoniaen
- King begoniaen
- Painted-leaf begoniaen
- Fancy-leaf begoniaen
- Begonia reginaes
- Bladbegonia / Kungsbegoniasv
- Bladbegonia / Kongebegoniano
- Bladbegonia / Kongebegoniada
- Lehtibegoniafi
- Königsbegonie / Blattbegoniede
India (Assam — type locality) · Northern Myanmar · Southern China (Yunnan) · Vietnam (north)
How to identify it
Growth habit. Rhizomatous: a thick fleshy creeping rhizome rests on or just below the soil surface, sending up petioles that hold individual leaves at 15–30 cm above the rhizome. The plant spreads sideways across the pot rather than upward — a 30 cm pot fills out in 12–18 months. There is no climbing or trailing form.
Leaves. Asymmetric heart-shaped leaves 10–25 cm long, on succulent reddish petioles. The defining ornamental feature: a colour zone (silver, pink, red, white) runs between the leaf centre and the margin, often bordered by a darker band. Leaf surfaces are slightly puckered or quilted. The asymmetry — one lobe of the heart larger than the other — is consistent across all rex begonias and is the single best ID feature.
Flowers. Small pale pink to white flowers in modest panicles above the foliage in spring. Flowering is incidental; rex begonias are grown almost entirely for their leaves. Most growers cut the flower stems off to direct energy into the rhizome.
- Asymmetric heart-shaped leaves with one lobe noticeably larger than the other.
- Distinct coloured zone running between the leaf centre and the margin (silver, pink, red).
- Rhizomatous: visible thick fleshy stem creeping on or just below the soil, with leaves rising from it.
- Reddish, often hairy petioles — succulent, not woody.
- No upright cane stems and no trailing habit — the plant spreads sideways across the pot.
Commonly confused with
Polka-dot begonia / Trout begonia
Cane-form begonia with upright bamboo-like stems and oval angel-wing leaves with white spots on green. Rex is rhizomatous and spreads sideways; maculata grows upward on canes.
Tuberous begonia
Tuberous begonias are grown for their large showy flowers (red, orange, pink) on stems above the leaves. They die back to a tuber every winter. Rex is grown for the leaves; flowers are insignificant.
Iron cross begonia
Another rhizomatous begonia, but with apple-green puckered leaves marked by a dark brown cross-shaped centre. No silver or pink zoning.
Care
Light
Bright indirect; never direct midday sun.
An east window or 60–100 cm back from a south or west window is ideal. Direct sun bleaches the colour out of rex leaves within hours and can scorch them outright. Low light produces dull, flat colour and stretched petioles; the colour zoning is light-dependent and weakens in dim rooms.
Water
Evenly moist; never soggy.
Water when the top 1–2 cm of mix feels dry — typically every 5–7 days in growth. Water around the edge of the pot, not on top of the rhizome (water on the rhizome causes rot). Bottom-watering also works well. Rex begonias rot in waterlogged soil within days; a free-draining chunky mix matters more than precise watering frequency.
Seasonal: Winter (Nov–March): cut watering frequency in half. Cool soil + wet rhizome = rot, the most common winter death cause.
Soil
Chunky, free-draining, peat-perlite-bark mix.
A mix of 2 parts peat-free potting soil, 1 part fine bark, and 1 part perlite holds enough moisture for rex begonias without going anaerobic. African violet mix works as a substitute. Avoid heavy moisture-retaining mixes — the rhizome sits on top and rots in soggy conditions.
Humidity
60 %+ ideal; visible decline below 50 %.
Rex begonias are the canonical 'humidity-needy' houseplant. Below 50 % humidity leaves go crispy at the edges within days; below 40 % the plant collapses. A pebble tray, room humidifier, terrarium, or grouping with other humidity plants all work. Misting alone is not enough — humidity drops back within minutes.
Seasonal: Nordic winters with central heating drop indoor humidity below 30 % — the single hardest season for rex begonias. A small humidifier near the plant is the best fix.
Temperature
18–24 °C; below 13 °C triggers winter rest.
Rex begonias prefer warm but not hot conditions. Below 13 °C they enter a winter rest with reduced growth; below 7 °C the rhizome can be damaged. Above 27 °C combined with low humidity, leaves go crispy fast.
Fertilizer
Half-strength balanced feed every 3–4 weeks during growth.
Feed at half strength every 3–4 weeks from spring through autumn. Stop entirely from October to February. A balanced houseplant feed is ideal — high-nitrogen feeds produce green vigorous leaves at the expense of colour zoning.
Pruning
Trim damaged leaves at the petiole base; cut flower stems to redirect energy.
Snip damaged or yellowed leaves at the petiole base. Most growers cut off flower spikes as they emerge — flowers are insignificant and divert energy from the rhizome. To encourage branching of the rhizome, cut a section back to a healthy node in spring.
Repotting
Every 2 years in spring, in a wide shallow pot.
Rex begonias are shallow-rooted and prefer wide, shallow pots ('azalea' or pan pots) over deep ones. Repot in spring when the rhizome reaches the pot edge. Plant the rhizome on the surface of the mix — burying it causes rot.
Leaf cutting (with petiole)
easy~4–8 weeksThe signature begonia propagation method. Cut a healthy mature leaf at the base of the petiole. Insert the petiole into damp mix or a glass of water; in 4–8 weeks tiny plantlets emerge from the cut surface where the petiole meets the leaf. Once plantlets have 2–3 leaves each, transplant into individual pots.
Leaf-section cutting (wedges)
easy~6–10 weeksCut a leaf into wedges, each containing a section of major vein. Plant each wedge upright with the vein-end in damp mix. Plantlets emerge from the vein where it meets the soil. A single leaf can yield 5–10 new plants this way.
Rhizome division
easy~2–4 weeksWhen repotting, cut the rhizome into sections each with at least one leaf and root system. Pot up separately in fresh mix.
Cultivars
'Escargot'
The icon of the rex group. Silver-green leaves spiral inward in a tight snail-shell coil — diagnostic and instantly recognisable. Slow but durable.
'Fireworks'
Black-purple leaves with broad silver-white spreading bands radiating from the centre, edged in pink. One of the most photographed cultivars.
'Red Kiss'
Deep wine-red leaves with a silver-blushed band and dark green margin. Compact form.
'Silver Limbo'
Dwarf cultivar with intensely silver leaves on dark stems. Holds colour at lower humidity than most rex begonias.
'Helen Teupel'
Long-leaved rex with strong purple base, silver banding, and pink edging. A reliable performer for terrariums.
Common problems
White powdery patches on leaves
Symptom
Dusty white patches that look painted on, spreading from leaf upper surfaces.
Cause
Powdery mildew — the most common rex begonia disease.
Fix
Improve air circulation immediately. Treat with a 1:10 milk-water spray or a sulphur-based fungicide every 7 days until clear. Remove and discard heavily infected leaves. Reduce humidity slightly (still above 50 %) and ensure no leaves stay wet overnight.
Crispy leaf edges and faded colour
Symptom
Margins go brown and brittle; colour zones look washed out.
Cause
Humidity below 50 %.
Fix
Add a humidifier near the plant. A pebble tray helps but is rarely enough alone. Rex begonias are not tolerant of dry air — this is the single most common care mistake.
Rhizome goes soft or smelly
Symptom
Whole plant collapses; the visible rhizome feels mushy.
Cause
Rhizome rot from waterlogged soil or water sitting on the rhizome.
Fix
Cut away all soft tissue with a clean knife back to firm white rhizome, dust with cinnamon, and replant in fresh dry chunky mix. Water around the pot edge, not on the rhizome.
All leaves drop in autumn
Symptom
Healthy plant suddenly drops most or all leaves as days shorten.
Cause
Natural winter rest, especially in cool conditions below 16 °C.
Fix
Stop feeding, reduce watering by half, and keep the rhizome warm and barely moist. New growth resumes in March–April. Don't discard a 'dead' rex begonia in autumn — check the rhizome.
- Mealybugs in leaf joints
- Spider mites in dry conditions
- Thrips on undersides
- Fungus gnats in soggy mix
- Powdery mildew (the rex begonia's nemesis)
- Botrytis grey mould in cool damp conditions
- Rhizome rot in soggy mix
- Bacterial leaf spot in stagnant air
Toxicity & safety
Insoluble oxalates cause mild to moderate burning of the mouth and lips on chewing, with drooling and difficulty swallowing. The rhizome is the most concentrated part.
Mechanism: Insoluble calcium oxalate crystals.
Begonia rex — North Carolina State Extension Toxic PlantsDrooling, oral pain, vomiting, and difficulty swallowing after ingestion. The rhizome is the most concentrated part. Contact a veterinarian if a cat chews any part of the plant.
Mechanism: Insoluble calcium oxalate crystals.
ASPCA Toxic and Non-Toxic Plants — BegoniaDrooling, oral pain, vomiting, and difficulty swallowing. Larger ingestions can cause kidney damage. Contact a veterinarian.
Mechanism: Insoluble calcium oxalate crystals.
ASPCA Toxic and Non-Toxic Plants — BegoniaHow to root a rex begonia from a single leaf
Begonia leaf propagation is one of the most satisfying things you can do on a windowsill. Cut a healthy mature leaf at the base of the petiole. Stick the petiole into damp seed-starting mix or a glass of water. Cover with a clear bag or place in a humid box and keep at 21 °C with bright indirect light.
In 4–8 weeks tiny plantlets emerge from the cut surface where the petiole meets the leaf base. Once each plantlet has 2–3 of its own leaves, separate them gently and transplant into individual small pots. Each leaf typically yields 1–3 new plants. The leaf-wedge method (cutting a leaf into pie-slices, each with a major vein, and planting each upright in damp mix) can yield 5–10 plants from a single leaf.
The species was introduced to Europe in 1857 in a single shipment of Indian orchids; nurserymen noticed the unrequested begonia at the bottom of the crate had spectacular leaves and started breeding it immediately. Within a decade Victorian nurseries had produced hundreds of named cultivars — the rex begonia is one of the fastest-bred and most cultivar-rich houseplants in horticultural history.
Frequently asked · 5
Are rex begonias toxic to cats and dogs?+
Yes — Begonia rex (and all rex-cultorum hybrids) is toxic to cats and dogs. All parts contain insoluble calcium oxalate crystals, with the highest concentration in the rhizome. Ingestion causes drooling, oral pain, vomiting, and difficulty swallowing. Contact a veterinarian if a pet chews any part of the plant.
How much humidity does a rex begonia really need?+
60 %+ for healthy long-term growth. Below 50 % humidity leaves go crispy at the edges within days; below 40 % the plant collapses. A small humidifier near the plant is the most reliable fix. Pebble trays alone are usually not enough in heated Nordic apartments.
Can I propagate a rex begonia from a leaf?+
Yes — leaf cuttings are the standard begonia propagation method. Stick a healthy leaf petiole into damp mix or water. Plantlets emerge from the cut surface in 4–8 weeks. Each leaf typically yields 1–3 new plants; the leaf-wedge method can yield 5–10.
Why are my rex begonia's colours fading?+
Either insufficient light or over-feeding. Rex colour zoning is light-dependent and weakens in dim rooms — move to a bright indirect spot. High-nitrogen fertiliser also produces vigorous green leaves at the expense of colour; use a balanced feed at half strength.
What's the difference between Begonia rex and rex-cultorum?+
Begonia rex is the wild Indian species; rex-cultorum is the trade name for the hybrids of B. rex × related Asian species that account for almost all garden-centre stock. Care is identical. Most plants sold simply as 'rex begonia' are technically rex-cultorum hybrids.
- Are Houseplants Toxic to Cats and Dogs? A Quick-Scan Safety Guide
- My Cat or Dog Just Ate a Houseplant — What to Do Right Now
- Begonia Varieties: Rex vs. Polka Dot vs. Angel Wing vs. Rhizomatous
- Humidity for Houseplants: What Actually Matters (and What Doesn't)
- Indoor Humidity for Houseplants in Winter: What Actually Works
- Powdery Mildew on Houseplants: Identify & Treat the White Dust