Rex Begonias are popular houseplants, cherished for their striking foliage in a wide array of colors, patterns, and textures. This guide provides comprehensive information on their specific care requirements to cultivate thriving plants.
Essential Care Requirements
Light Needs
Rex Begonias flourish in bright, indirect light. East-facing windows or a few feet back from south/west-facing windows provide suitable illumination. Direct sunlight can scorch delicate leaves, causing browning or fading. Insufficient light can cause variegation to fade and leggy growth. If natural light is limited, Rex Begonias thrive under fluorescent grow lights.
Watering Practices
Rex Begonias need consistent moisture but are sensitive to overwatering. Allow the top inch or two of potting mix to dry before rewatering. Water thoroughly until drainage, then empty excess water from the saucer. Overwatering quickly leads to root rot. Overly dry soil causes wilting or soft leaves.
Humidity and Temperature
Rex Begonias thrive in high humidity, ideally 50% or higher. Low humidity can cause leaf edges to become crisp or brown. Increase humidity by grouping plants, using a pebble tray, or a humidifier. Avoid misting leaves directly, as this can encourage fungal diseases like powdery mildew.
Moderate temperatures (60-75°F / 15-24°C) are preferred. Growth tends to slow below 60°F. Protect from sudden temperature changes and cold drafts, which can cause wilting or leaf discoloration.
Soil Mix
Rex Begonias need a well-draining, airy, light potting mix. A peat-based mix (pH 5.7-6.4) is recommended for their fine root systems. Incorporating perlite or orchid bark can improve drainage. Porous pots (ceramic, terra-cotta) also aid moisture regulation.
Fertilizing
During the active growing season (spring through early fall), fertilize regularly. A diluted balanced liquid fertilizer every two to three weeks is sufficient. Avoid fertilizing during winter months when growth slows. Sensitive to salt buildup, proper drainage and occasional soil flushing are beneficial.
Pruning and Repotting
Pruning maintains shape and encourages fuller growth. Remove dead, yellowing, or damaged leaves with clean pruning shears. If leggy or too large, trim stems above a leaf node to promote new growth. Pinching younger plants encourages a bushier habit.
Rex Begonias prefer to be slightly root-bound, so frequent repotting is unnecessary. Repot every two to three years, or when rhizomes press against the pot sides. Repot during warmer spring and summer months when the plant is actively growing. Select a slightly larger container to avoid excess soil retaining too much moisture.
Propagating Rex Begonias
Propagating Rex Begonias is straightforward via leaf cuttings. Select a healthy, mature leaf. Using a clean, sharp blade, make several 1-inch cuts through the main veins on the leaf’s underside.
Place the leaf, top-side up, onto a moist, well-draining rooting medium (e.g., sterile seed-starting mix, perlite, sphagnum moss). Weigh down the leaf for good contact between cut veins and the rooting medium. Covering the pot with plastic wrap or using a propagator creates high humidity for root development. New plantlets typically form from cut veins within three to four weeks; once established, divide and pot individually.
Common Problems and Solutions
Rex Begonias can experience issues, often related to improper care.
Leaf Issues
Leaf browning, curling, or wilting indicates underwatering or overwatering, requiring watering adjustments and proper drainage. Yellowing leaves, especially older ones, signal overwatering or insufficient light. Root rot (mushy, dark roots, wilting) is caused by overwatering and poor drainage; trim affected roots and repot in fresh, well-draining soil.
Pests
Mealybugs are small, white, cotton-like masses at leaf and stem joints. Spider mites (thriving in dry conditions) cause tiny yellow or whitish stippling and fine webbing on leaves. Aphids are small, sap-sucking insects clustering on new growth. For these pests, manual removal with an alcohol-dipped cotton swab or treatment with insecticidal soap or neem oil is effective.
Fungal Diseases
Fungal diseases like powdery mildew (white spots) and botrytis blight (fuzzy gray/brown spots) affect leaves and stems. They link to high humidity, poor air circulation, or wet foliage. To prevent and manage fungal issues, improve air circulation, avoid wet leaves during watering, and promptly remove affected plant parts. A systemic fungicide may be necessary in some cases.