African milk tree
Also known as
Cathedral cactus, Cathedral euphorbia, Friendship cactus, Euphorbia ‘Rubra’ (red form)
Keep this plant’s care guide close at hand.
Get the appAbout African milk tree
Euphorbia trigona, commonly called the African milk tree, is a fast-growing, shrubby succulent native to Central Africa. Despite its cactus-like silhouette, it belongs to the Euphorbia genus and exudes a milky latex when cut. Upright, triangular, green stems form candelabra-like columns with pronounced ridges lined by paired spines and small, deciduous, lanceolate leaves. Over time it can reach 4–8 feet indoors and taller outdoors in frost-free climates, developing multiple branches from the base. The species is prized for architectural presence, drought tolerance, and ease of culture, and is widely grown as a houseplant or thorny hedge in the tropics. Varieties such as ‘Rubra’ display reddish or variegated tones under strong light. True flowers are rarely produced in cultivation. Like many euphorbias, it prefers excellent drainage, bright light, and infrequent watering. The latex sap is caustic, so handling requires care. Propagation is straightforward from cuttings taken in warm weather and allowed to callus before rooting in a gritty medium.
Taxonomy
Properties & Requirements
How to care for African milk tree
Water
Follow a deep-soak, full-dry cycle. Water thoroughly until excess drains, then allow the mix to dry completely before watering again; indoors this often means every 2–4 weeks in summer and 4–6+ weeks in winter. Confirm dryness by checking 2–3 inches deep or using a moisture meter. Use pots with drainage and avoid water sitting in saucers. Reduce frequency markedly in cool, low-light periods to prevent root rot.
Light
Provide very bright light: at least 4–6 hours of direct sun indoors (south or west window). Outdoors, acclimate over 1–2 weeks to tolerate full sun; intense midsummer sun may scorch unacclimated plants. Insufficient light causes lanky, leaning growth and small, sparse leaves. Supplemental grow lights (PPFD ~200–400 µmol/m²/s for 12–14 hours) can maintain compact form. Variegated ‘Rubra’ needs more light to retain color.
Nutrients
Feed lightly during active growth (spring–summer) with a cactus/succulent fertilizer at 1/4–1/2 strength every 4–6 weeks. A balanced or slightly low-nitrogen formula with micronutrients works well. Do not fertilize in winter or when temperatures are below 60°F (16°C). Flush the soil with plain water every few months to reduce salt buildup. Avoid fertilizing immediately after repotting; wait 4–6 weeks.
Temperature
Ideal range is 65–85°F (18–29°C). Keep above 50°F (10°C) at all times; brief exposure to 45°F (7°C) may be tolerated if the soil is dry, but frost will damage tissues. In hot spells above 95°F (35°C), provide airflow and light shade during peak sun, especially for variegated forms. Cold, wet conditions are the main rot risk; ensure the root zone dries promptly and avoid chilly drafts.
