Rex Begonia is a herbaceous perennial plant native to Southeast Asia. The houseplant has colorful foliage that exhibits shades of green, red, pink, and purple.
The Rex Begonia belongs to the extensive group of Rex cultorum, with several generations of hybrids. The leaves of Rex Begonia plants vary in shape, size, and color. Some have heart-shaped leaves with a silver streak, while others have seashell swirls with jagged edges.
| Scientific Name | Begonia rex |
| Common Name | Begonia |
| Family | Begoniaceae |
| Genus | Begonia |
| Origin | Southeast Asia |
| USDA Hardiness Zones | 10-12 |
| Propagation Methods | Rhizome division, leaf cuttings |
| Temperature Tolerance | Warm climates |
| Soil Requirements | Well drained |
| Humidity Level | Very high |
Rex Begonia Varieties
The Rex plant exists in hundreds of hybrids and cultivars. Rex Begonia varieties have variegated leaf patterns and colors. The most popular hybrids include:
Begonia ‘Fireworks’
This begonia cultivar features a strong black, metallic silver, and vivid purple coloration. Being an upward-growing variety, ‘Fireworks’ can grow up to 25 cm tall with leaves 15 cm long.
Begonia ‘River Nile’
This hybrid has ruffled, lime-green leaves with deep bronze edges. The leaf stems are succulent with a pale yellow strain and contrasting red flecks. The ‘River Nile’ grows up to 2 feet tall.
Begonia ‘Escargot’
This cultivar features spiral-shaped foliage with green, silver, and chocolate colors. These form a snail-curl pattern at the leaf’s base. A mature ‘Escargot’ can grow up to 6 feet tall.
Begonia ‘Shadow King Lava Red’
Red begonia features a bright and crisp colored red leaf with gray veining. It grows up to 2 feet tall.
Rex Begonia Plant Care
Light Requirements
Rex Begonias grow well in bright, indirect sunlight. Prolonged exposure to sunlight could burn the plant’s foliage. Use LED plant grow lights during fall or winter to compensate for the light period required.
Soil Mix and Composition
The Rex Begonia requires well-draining, aerated soil. A peat-based potting mix with a pH of 5.7-6.4 is ideal. Enrich the soil with organic manure by adding compost to improve plant growth and nutrient intake.
Potting and Transplanting
Pot your Rex Begonia in a shallow container with fresh, porous soil. The soil should be well-aerated and have optimal drainage. Stick a finger inside the soil to check the moisture level before watering.
When the rhizomes begin to butt up on the pot’s sides, it’s time to transplant to a new pot with fresh soil. Divide the rhizome when repotting to avoid transplant shock.
Temperature and Humidity
Rex Begonias grow well in moderate temperatures between 60 to 70 degrees Fahrenheit, with a 50% humidity. Avoid misting, which leads to powdery mildew problems and bacteria leaf spots.
The Begonias tend to grow larger in higher humidity. Increase the moisture content during winter using a tray of wet pebbles or a humidifier.
Watering and Drainage
Ensure the soil is moist, letting the top inch dry out completely before watering. Test the soil’s moisture with your finger. Don’t overwater your plant since it leads to root rot due to a lack of air in the soil. Ensure to maintain a regular watering schedule to avoid withering of its foliage.
Pruning and Training
Rex Begonias need pruning when they start growing and develop bare stems. Use clean snips to cut the stem back to the base. The remaining part should sprout with new leaves and stems. Pinch the top of the plant to grow full, lush foliage.
Rex Begonia Plant Propagation
Most begonias available are hybrids, making it challenging to propagate using seeds. Rhizome division and leaf cuttings are the main propagation methods.
Rhizome Division
- Lift your Rex Begonia out of the pot to avoid injuring the roots.
- Dust off the roots to make them visible and easier to work with.
- Untangle and remove any dead or damaged roots. Use a clean pair of disinfected pruning shears.
- Take off the divided stalk roots with your bare hands.
- Leave the roots to dry while preparing the potting mix with well-drained and porous soil.
- Repot in a new container while maintaining the soil moisture.
- Keep it from direct sunlight for a few weeks to recover from rebound stress.
Leaf Cuttings
- Use clean, sharp, and sanitized cutting shears to cut off three inches of a leaf petiole. A petiole is the stalk that joins the leaf to the plant stem.
- Finish the cut by trimming the leaf’s base and cleaning the jagged edges.
- Dip the cut into a rooting hormone to help with a successful propagation.
- Prepare your pot with porous soil. Use a stick to make a hole in the pot for the petiole.
- Stick the petiole into the hole at a 45-degree angle while packing the soil around it to make it stand upright.
- Wrap the leaf-cutting in a plastic wrap to trap moisture and promote quick growth. Use tape to secure the plastic wrap to the cutting.
- Don’t remove the plastic wrap until the first sprouts show up.
- Check the pot occasionally to ensure sufficient soil moisture.
- In 4-6 weeks, the leaf-cutting should have developed a root system.
Pest and Disease Management
Mealybugs
Mealybugs are small, soft, wax-like insects that feed on the plant’s sap. Affected plants get distorted leaves that spread to other plants. Control any single-site infestation with a cotton swab saturated with rubbing alcohol.
Scales
Scales are small, round insects with a hard shell. There are two types of scale: soft scale and hard scale. The soft scale leaves a honey-like residue, while the hard scale doesn’t. Spray soapy water or use a cotton swab to rub alcohol on the infested areas.
Whiteflies
These are tiny white insects found on the leaf’s undersides. Spray soapy water on infested areas or set sticky traps near plants to eliminate them.
Powdery mildew
This is a white powdery substance on leaf surfaces, stems, and buds. It appears in cool temperature environments with high humidity and poor ventilation.
Troubleshooting Common Problems
Yellowing leaves
Yellow leaves are a sign of overwatering. Use a light potting mix while ensuring the pot has adequate drainage holes. Amend soil with peat to help with the absorption of excess water.
White spots on leaves
White spots are a sign of powdery mildew. Continued exposure to powdery mildew leads to stunted growth. Bottom water your plant. Get rid of excess water to reduce the chances of powdery mildew.
