What is a Rex begonia?
Rex begonias (Begonia rex) are a group of rhizomatous begonias grown almost entirely for their foliage rather than their flowers. The leaves are the spectacle — swirling spirals, metallic silvers and purples, deep burgundy undersides, and two-tone zoning that shifts with the viewing angle. They belong to the family Begoniaceae and are native to subtropical regions of Asia, though the cultivar range now spans thousands of named selections developed by collectors worldwide.
Unlike cane or trailing begonias, Rex types are compact and low-growing, spreading sideways from a shallow rhizome rather than growing tall. That makes them ideal shelf and windowsill plants where the leaf detail can be admired up close.
How much light does a Rex begonia need?
Rex begonias want bright, indirect light — and getting this right is the key to vivid leaf color. The metallic and purple pigments develop most intensely in good but filtered light. Too dim, and patterns fade toward plain green; too much direct sun, and the thin leaf tissue scorches or bleaches within days.
A north- or east-facing windowsill, or a spot a few feet back from a bright south or west window, typically works well. Under artificial light, a full-spectrum LED grow lamp at 12–14 hours per day keeps colors rich without any burn risk.
How often should you water a Rex begonia?
Water about every 1–2 weeks, letting the top inch of soil dry out between waterings. Rex begonias are more rot-prone than most begonias because their rhizomes sit close to the soil surface — a constantly damp pot is the fastest way to lose one.
Bottom watering is strongly recommended. Set the pot in a shallow dish of water for 20–30 minutes, let the soil absorb what it needs from below, then tip out any remaining water. This keeps the leaves perfectly dry and dramatically reduces the risk of powdery mildew and leaf spots.
What humidity does a Rex begonia need?
High humidity — ideally 50–70% — keeps the leaves lush and prevents brown edges. A pebble tray with water under the pot, grouping plants together, or running a small humidifier nearby all work well. Avoid misting directly onto the leaves: Rex begonias are uniquely susceptible to powdery mildew, and wet foliage is the main trigger.
Room temperature between 60–80°F (15–27°C) suits them well. Avoid cold drafts, heating vents, and temperatures below 55°F — they are not frost-tolerant.
What are Rex begonia cultivars and how do they differ?
The Rex begonia category contains thousands of named cultivars, each with distinct leaf markings that behave slightly differently in cultivation:
- ‘Escargot’ — The most iconic, with a tight silver-and-green spiral from base to tip. Slightly more forgiving of lower humidity than finer-leaved types.
- ‘Fireworks’ — Deep burgundy center, silver-streaked outer zone, and serrated edges. Needs consistent humidity to hold crisp margins.
- ‘Red Robin’ — Bold red-burgundy with silver spotting; tolerates slightly lower light than most Rex types while holding color.
- ‘Stained Glass’ — Translucent silver-pink center with dark wine edging; one of the most delicate and humidity-sensitive.
All cultivars share the same core care needs but vary in how quickly they drop leaves if humidity drops suddenly. Start with ‘Escargot’ if you are new to Rex types — it is the most resilient.
Is a Rex begonia toxic to pets?
Yes — the ASPCA lists Begonia spp., including Rex begonias, as toxic to cats and dogs due to soluble calcium oxalates. Symptoms of ingestion include oral irritation, excessive salivation, and vomiting. The rhizomes and tubers contain the highest concentration of the toxin, though the leaves and stems are also a risk. Keep Rex begonias on high shelves or in rooms that pets cannot access.