The African Milk Tree (Euphorbia trigona) is a distinctive succulent often cultivated indoors. Despite its name, it is not a true tree or cactus, but a unique succulent known for its architectural form. Its upright, columnar stems feature three prominent ridges lined with small, sharp thorns and occasional teardrop-shaped leaves. This plant’s resilience and ease of care make it popular among enthusiasts.
Understanding African Milk Tree Growth
The African Milk Tree grows at a moderate to fast rate under optimal conditions. Indoors, it grows about 1 to 2 feet per year, reaching 6 to 9 feet as a houseplant. Outdoors, Euphorbia trigona can reach up to 10 feet tall.
New growth appears as extensions of existing stems or as new branches from the sides, contributing to a dense, candelabra-like form. Growth involves the lengthening of existing segments and the development of new segments at the tips or sides of the stems.
Key Factors Influencing Growth
Several environmental and care factors affect the African Milk Tree’s growth and health. Bright, indirect light is generally favored for robust growth; insufficient light can lead to etiolation, where the plant stretches and becomes leggy, while excessive direct sun, particularly harsh midday rays, can cause scorching and stunted growth.
Proper watering is crucial, as this succulent stores water in its fleshy stems. Overwatering can lead to root rot and stunted growth, while persistent underwatering will also stunt growth and cause the plant to shrivel. Soil composition plays an important role, requiring excellent drainage to prevent waterlogging.
Temperature and humidity also impact development. The African Milk Tree thrives in warm conditions, ideally between 65°F and 85°F (18°C to 29°C), and does not tolerate temperatures below 40°F (4°C). It prefers low to moderate humidity, typical of arid environments, and does not require high humidity. The plant enters a semi-dormant period during fall and winter, slowing growth, which influences nutrient needs.
Cultivating Optimal Growth
To encourage healthy growth, specific cultivation practices are beneficial for the African Milk Tree. Providing ample bright, indirect light is important; a south or west-facing window, where the plant receives several hours of sun without intense midday exposure, is suitable indoors. If natural light is limited, supplemental grow lights can support healthy development.
Watering should be deep but infrequent, allowing the soil to dry completely between waterings to prevent root rot. During the active growing season in spring and summer, watering may occur approximately weekly, while in fall and winter, it should be reduced to every 4-6 weeks. A well-draining soil mix, such as a commercial cactus or succulent blend, works well.
Modest fertilization during the growing season can further support growth. A balanced, low-nitrogen or cactus-specific fertilizer can be applied monthly from spring through summer. Maintaining temperatures within the preferred range and ensuring good air circulation without cold drafts also contributes to good conditions.
Repotting every 2-3 years into a pot only 1-2 inches larger in diameter can provide fresh soil and space for root expansion, supporting continued growth.
Managing Plant Size
As the African Milk Tree can grow tall, managing its size and shape is necessary. Pruning controls height, encourages branching, and removes damaged or undesirable sections. When pruning, it is important to use a sharp, sterilized knife or scissors and to wear gloves and eye protection due to the milky, irritating sap the plant produces.
Cutting the stem just above a segment or where new branching is desired helps shape the plant. After pruning, allow the cut end to callous for a few days to prevent issues. While pruning helps manage vertical growth, keeping the plant slightly pot-bound can also naturally slow its growth rate. Selecting a heavy, wide-bottomed pot, such as terracotta, provides stability for taller plants, preventing them from becoming top-heavy.