The Royal Red African Milk Tree (Euphorbia trigona ‘Rubra’) is a striking succulent, popular for its architectural form and vibrant color. This guide covers its care, propagation, and common challenges.
Understanding Your Royal Red African Milk Tree
The Royal Red African Milk Tree (Euphorbia trigona ‘Rubra’) is a succulent, not a true cactus, characterized by spiny, columnar, triangular stems with ridged edges, small thorns, and tear-shaped leaves. The ‘Rubra’ cultivar’s reddish hue intensifies with sufficient light and temperature. It grows fast, upright, and branches, forming a tree-like structure.
All Euphorbia species produce a toxic milky sap when damaged. This sap can cause skin irritation or blistering on contact, and if ingested, leads to gastrointestinal upset in humans and pets. Handle with care, wearing gloves and eye protection, and keep out of reach of children and animals.
Essential Care for Royal Red African Milk Tree
Light Requirements
The Royal Red African Milk Tree thrives in bright, indirect light, tolerating some direct sun. A south-facing window is ideal indoors. Adequate light maintains its vibrant red coloration; insufficient light causes stems and leaves to revert to green. Excessive direct sun, especially in summer, can lead to scorching.
Watering Practices
As a drought-tolerant succulent, the African Milk Tree stores water in its fleshy stems. Overwatering is the most common mistake, causing root rot. Allow soil to dry completely between waterings. During the spring and summer growing season, water weekly until drainage. In fall and winter, reduce watering to once every 4-6 weeks, or when soil is completely dry.
Soil and Drainage
Proper drainage is necessary for the Royal Red African Milk Tree. It requires well-draining soil to prevent waterlogged conditions and root rot. A commercial cactus or succulent mix is ideal. For enhanced drainage, amend standard potting soil with perlite, coarse sand, or pumice (50-75% mineral grit). Pots with drainage holes, like terracotta, aid moisture control and aeration.
Temperature and Humidity
The African Milk Tree prefers warm temperatures (65-85°F / 18-29°C). It tolerates brief drops but is not frost-hardy; protect from temperatures below 40°F (4°C). Consistent temperatures are beneficial, as prolonged exposure below 50°F (10°C) can harm it. This succulent adapts to dry air and performs well in average household humidity (40-60%). Avoid misting and high humidity.
Fertilization
African Milk Trees do not require heavy fertilization. During spring and summer, they benefit from occasional feeding. Use a balanced, low-nitrogen, or specific cactus/succulent fertilizer. Fertilize once a month, diluted to half strength, to prevent root damage or leggy growth. Avoid fertilizing in fall and winter dormancy to prevent salt buildup.
Propagating and Repotting
Propagate the Royal Red African Milk Tree using stem cuttings. Select a healthy stem at least 6 inches long and make a clean cut with a sharp, sterilized knife. Allow the cut end to dry and form a callus for several days to a week; this prevents rot. Once callused, plant the cutting an inch deep into a small pot with well-draining cactus or succulent mix. Water sparingly until roots establish (several weeks), and place in bright, indirect light.
Repotting is not an annual requirement, but repot when roots emerge from drainage holes or the plant becomes top-heavy. Choose a pot one size larger with drainage holes, sturdy enough to support its height. Use fresh, well-draining succulent or cactus mix. When repotting, carefully remove the plant, spread tangled roots, and place it in the new pot, filling with soil. Always wear gloves to protect from the milky sap.
Addressing Common Challenges
Stem rot, caused by overwatering or poor drainage, is a frequent problem. Symptoms include mushy, yellowing, or browning stems. If detected, remove affected parts by cutting to healthy tissue and allow cut areas to callus before resuming watering. Proper watering and well-draining soil prevent rot.
Loss of red coloration indicates insufficient light. Move the plant to a brighter location with ample indirect sunlight to restore vibrant hues. Excessive direct sun can cause sunburn (burnt patches).
African Milk Trees are resistant to most pests, but mealybugs or spider mites can affect them. Cotton-like threads or small webs indicate their presence. Treat these pests by wiping them off with a cloth dipped in diluted mild dish soap and water, or by using insecticidal soap or neem oil.
Stem shriveling or wrinkling signals underwatering or severe root rot. If soil is bone dry and stems appear deflated, water the plant. If soil is consistently wet and stems are soft and mushy, it indicates root rot, requiring immediate intervention.