Description

Euphorbia trigona ‘Rubra’ (often sold as Red African Milk Tree) is a sculptural, upright succulent known for its tall, triangular, ribbed stems studded with paired spines and lined with small, paddle-shaped leaves. In strong light, the stems and leaves can flush deep burgundy to wine-red, contrasting attractively with olive-green seams. This species forms a candelabra silhouette as it matures, branching above the base and creating a dramatic architectural presence indoors or on sunny patios.

Note: Like many euphorbias, it exudes a white, milky latex when cut or bruised. This sap is a strong irritant and is toxic if ingested—use gloves and eye protection when handling.

Suggested Uses

• 
  Modern Containers A bold, vertical accent for minimal, contemporary pots. Choose a heavy container to counterbalance height.
• 
  Bright Interiors Thrives near south or west windows, sunrooms, and bright offices. Rotate regularly for even color and form.
• 
  Patio and Porch Summer outdoors in bright light; acclimate gradually to direct sun to avoid scorch, and bring indoors before frost.
• 
  Xeric Combinations Pairs beautifully with Aloe, Haworthia, Gasteria, and Sansevieria (Dracaena trifasciata) in low-water groupings.

Plant Details

• Botanical NameEuphorbia Trigona Red African Milk Tree (syn. Euphorbia trigona ‘Rubra’)
• Common NameEuphorbia Trigona; also called Red African Milk Tree, Cathedral Cactus (not a true cactus)
• Size & GrowthUpright, columnar habit. Indoors typically 4–8 ft (1.2–2.4 m); outdoors in frost-free climates 8–15 ft (2.4–4.5 m). Branches with age.
• Hardiness ZonesUSDA 10–11. Protect from temperatures below ~55°F (13°C); not frost tolerant.
• Foliage TypeEvergreen succulent stems with paired spines; small leaves along ridges may shed in low light or winter dormancy.
• Bloom TimeRare in cultivation; occasional, small inconspicuous cyathia in warm seasons. Grown for form and color, not flowers.
• Growth RateModerate to fast in bright light and warm conditions; slows significantly in winter.
• Light RequirementsBright, indirect light to 4–6+ hours of direct sun. Strong light intensifies red coloration; acclimate to avoid sunscald.
• Attracts PollinatorsLow; flowers are rare indoors and generally not significant to pollinators.
• Indoor FriendlyYes—excellent houseplant when provided with ample light and infrequent watering.
• Container FriendlyThrives in containers with drainage; choose a stable, heavy pot to support height as it matures.
• Deer ResistantYes—the milky latex deters browsing by deer and rabbits.
• Pet WarningToxic if ingested; sap is caustic to skin and eyes. Keep away from pets and children; handle with gloves.
• FragrantNo fragrance; valued for form and stem color.
• Cut FlowerNot suitable as a cut flower due to irritating latex sap and spines.
• Grows Well WithGrows Well With Aloe (A. vera, A. aristata), Haworthia, Gasteria, Sansevieria (Dracaena trifasciata), and other low-water succulents with similar light needs.

Care Tips

• Planting InstructionsUse a pot with a drainage hole. Fill with a well-draining cactus/succulent mix. Set the plant at its original depth—do not bury the stem ribs. Backfill gently and avoid watering for 3–5 days after repotting to allow any wounds to callus. Always handle with gloves and eye protection.
• Soil MoistureWater deeply, then allow 50–75% of the mix to dry before watering again. In winter, water sparingly—about every 3–4 weeks or when fully dry. Never let the pot sit in water.
• Soil TypeFast-draining cactus mix amended with 30–50% pumice or perlite (or coarse sand). Target pH slightly acidic to neutral (≈6.0–7.5).
• HumidityAverage indoor humidity (30–50%) is ideal. Ensure good air circulation; avoid persistently humid, stagnant environments.
• Pruning InstructionsPrune in spring/summer to control height or remove damaged branches. Wear gloves and eye protection; the sap is caustic. Rinse sap with cool water and let cuts dry and callus. Allow cuttings to callus 5–7 days before rooting.
• Winter CareKeep above 55°F (13°C) and in the brightest spot available. Reduce watering and do not fertilize. Protect from cold drafts and any frost exposure.
• Planting DepthPlant at the same soil line as the nursery pot—keep the stem ribs above the mix. For cuttings, insert 1–2 in (2.5–5 cm) into dry, gritty mix after callusing.
• FertilizationLight feeder. Apply a balanced, low-nitrogen cactus fertilizer at 1/4–1/2 strength every 4–6 weeks in spring–summer. Do not feed in fall–winter.
• Special CareRotate the pot monthly for even growth and color. Stake if top-heavy; repot every 2–3 years into a slightly larger, heavy container. Watch for mealybugs and scale; wipe dust off stems. Avoid contact with latex sap.