Rex Begonia Care Guide
Rex begonias (Begonia rex-cultorum) are rhizomatous begonias grown entirely for their extraordinary foliage. The leaf patterns are among the most complex and varied of any houseplant group, with combinations of metallic silver, deep burgundy, vivid pink, copper-green, and white in spiraling, zoned, or brushstroke arrangements. The base of each leaf spirals inward at the point where the petiole attaches, a characteristic of the rex-cultorum group. Plants stay compact, typically 25 to 45 centimeters in spread, and suit windowsill or shelf positions where the foliage can be examined closely.
Quick Reference
| Factor | Requirement |
|---|---|
| Light | Bright indirect light |
| Water | Allow top 1 to 2 cm to dry; never wet the leaves |
| Humidity | 50 to 70 percent |
| Temperature | 18 to 24 degrees Celsius; cooler than most tropical houseplants |
| Soil | Well-draining, lightweight mix |
| Fertilizer | Balanced liquid fertilizer monthly at half strength, spring through early autumn |
| Pot | Shallow container with drainage holes |
| Toxicity | Toxic to cats and dogs |
Light and Foliage Color
Bright indirect light maintains the color intensity and pattern contrast that makes rex begonias distinctive. In lower light, the metallic sheens fade, the color combinations become muted, and growth slows. In direct sun, the large, decorative leaves scorch and develop pale, dry patches. An east-facing window or a position close to a bright north or west-facing window provides the right balance.
Watering
Water at the base of the plant only. Rex begonias are particularly susceptible to leaf spotting, petiole rot, and stem rot when water contacts the foliage or collects at the crown of the plant. Allow the top one to two centimeters of potting mix to dry before watering. Rex begonias have a relatively shallow rhizomatous root system that is susceptible to overwatering: a lightweight, well-draining mix and a container with drainage holes are essential.
In winter, reduce watering significantly. Rex begonias grow more slowly in lower light and cooler temperatures, and the mix dries down more slowly. Some rex begonias become partially or fully dormant in winter, losing some or all of their leaves. This is normal. Reduce watering to a minimum during this period and resume normal care when new growth appears in spring.
Humidity and Temperature
Rex begonias need higher humidity than most other begonias: 50 to 70 percent produces the best foliage development. They are also slightly more temperature-sensitive than cane-types, preferring 18 to 24 degrees Celsius and performing less well in consistently warm or hot rooms. Keep away from heat sources, radiators, and hot air vents.
Propagation
Rex begonias propagate uniquely well from leaf cuttings. A single leaf placed with its petiole in moist propagation mix will produce multiple plantlets at the base of the petiole within four to eight weeks. Alternatively, a leaf cut into sections, each containing a main vein, will produce plantlets from the vein contact points when laid on moist mix. The full technique for both methods is in the how to propagate begonias guide.
For root rot treatment if overwatering has occurred, the how to treat and prevent root rot guide covers the full process applicable to shallow-rooted rhizomatous plants.