The Euphorbia trigona ‘Royal Red’ is a striking succulent commonly known as the African Milk Tree or Cathedral Cactus. This cultivar is sought after for its deep ruby-red to magenta coloration that flushes across its upright, three- or four-sided stems. Its architectural shape and vibrant hue make it a popular and visually dynamic houseplant. It remains relatively low-maintenance and thrives in indoor settings.
Creating the Ideal Environment
To cultivate the signature deep burgundy coloration of the ‘Royal Red’ variant, the plant requires significant exposure to bright light. Placing it near a south- or west-facing window is ideal, as it needs several hours of direct sunlight daily to intensify its pigments. Insufficient light exposure will cause the stems to revert to a duller green. This may also result in etiolation, where the plant stretches and becomes spindly.
The Euphorbia trigona prefers consistent, moderate temperatures typical of a standard home environment, ideally ranging between 60°F and 75°F. Protecting the plant from temperatures dropping below 50°F is important, as cold drafts or low temperatures can cause damage. Due to its succulent nature, this plant does not require high humidity and is suited to the average dry air found indoors.
Routine Care and Maintenance
Overwatering is the primary cause of plant failure for the African Milk Tree. A “soak and dry” method is recommended: thoroughly saturate the soil until water drains from the bottom, then allow the entire volume of soil to dry out completely before watering again. During the active growing season in spring and summer, this may mean watering as often as once a week, depending on temperature and light exposure.
Watering frequency must be reduced during the plant’s winter dormancy, often requiring water only once every four to six weeks. The plant stores moisture in its fleshy stems, making it highly drought-tolerant; it is better for the plant to be slightly too dry than too wet. The correct soil composition is paramount, requiring a well-draining, gritty medium like a commercial cactus or succulent mix to prevent water retention around the roots.
The container must feature a drainage hole, as standing water will quickly lead to root rot. Repotting is an infrequent task, typically only necessary every two to three years or when the plant has outgrown its container. When repotting, select a new container only one to two inches larger in diameter to avoid holding excessive moisture around the roots.
Fertilization should be approached conservatively, as this plant is not a heavy feeder. During the active growth months of spring and summer, a diluted succulent or cactus fertilizer can be applied monthly. Apply the fertilizer at half or quarter strength to prevent chemical burn. Cease feeding entirely when the plant enters its slower growth phase in fall and winter.
Propagation and Safe Handling
New Euphorbia trigona plants are easily started from stem cuttings taken during the growing season. Use a clean, sharp knife to remove an arm, making a cut at a joint or near the main stem. Following the cut, the severed end must be allowed to rest and dry for several days until a hard, dry layer, known as a callus, forms over the wound.
Planting the cutting before callousing is complete increases the risk of fungal infection and rot. Once the callus has formed, the cutting can be placed directly into dry, well-draining soil. Watering should be withheld for another week or two to encourage root formation without rot. The most important consideration when handling this plant is the white, milky substance that exudes from any cut or damaged area.
This substance, characteristic of the Euphorbia genus, is a toxic latex that acts as a strong skin and eye irritant. Contact with the sap can cause rashes or blistering on the skin, and it is toxic if ingested by humans or pets. Therefore, wear gloves and consider eye protection when pruning or taking cuttings. Ensure the plant is kept in a location inaccessible to children and household animals.