Euphorbia trigona

Central African range and habitat of Euphorbia trigona

Euphorbia trigona is native from Gabon to Malawi, including Angola, the Republic of the Congo and the Democratic Republic of the Congo. It grows as an upright succulent shrub or small tree in warm central and south-central Africa.

The species grows in places with a pronounced dry season, where the ground dries well between seasonal rains.

Caring for Euphorbia trigona indoors

• Repotting and balance: Move to a larger pot when roots are crowded or the plant begins to tip. A broad, heavy pot helps steady mature plants.
• Light: Place it in very bright light; established plants can take direct sun when it is introduced gradually. Light from several directions helps keep the vertical branches balanced.
• Watering: Wait until the potting mix is dry throughout, then water well. When leaf and branch growth slows or pauses, water less often, always waiting for the mix to dry completely first.
• Potting mix: Use a loose, gritty succulent mix that drains quickly around the roots.
• Temperature: An indoor temperature around 15–24 °C suits new growth well. Keep the plant around 10 °C or above.
• Humidity and airflow: Low to average room humidity is suitable. Give the lower stem good airflow.
• Feeding: Use a diluted succulent fertiliser while new leaves and branches are growing.
• Propagation: A healthy side branch can be rooted after the cut has dried and sealed. Wear gloves and eye protection because the stems release irritating latex.

Problems and solutions for Euphorbia trigona

• Leaves fall while the green stems stay firm: Temporary leaf loss can follow slower growth, reduced light or another change in conditions. Check that the stems are firm and make sure the plant is still getting bright light. If growth has paused, leave the mix dry for longer between waterings. If the plant is still growing in dim light, move it gradually into a brighter position.
• The lower stem becomes soft or black: A soft or black lower stem can indicate rot after the potting mix has stayed wet too long. Stop watering, unpot the plant and cut away all soft or rotten tissue with a clean tool until only firm, healthy tissue remains. Discard the rot and let the cut seal before repotting or rooting the healthy part.
• Stems lean strongly toward one side: A strong lean can result from uneven light, a top-heavy crown, or both. Give it bright light from several directions, rotate the pot gradually and use a heavier pot if the plant is unstable.
• White cottony clusters or fixed brown bumps appear: Check the rib edges and leaf bases for mealybugs or scale. Isolate the plant, remove visible pests and use a treatment labelled for the insect you find, repeating it only as directed.

Euphorbia trigona is toxic to people and pets

• Keep this plant away from children, cats and dogs, and avoid contact with its milky sap.
• The sap contains irritating diterpene esters that can burn the mouth and damage skin or eyes.
• Sap exposure may cause painful irritation, while swallowing plant material can cause vomiting or stomach pain. Contact a veterinarian or medical professional promptly, especially after eye exposure.

About the name Euphorbia trigona

Euphorbia honours Euphorbus. Trigona means three-angled, referring to the characteristic stem form.

Carl Linnaeus established the genus Euphorbia in 1753 in Species Plantarum, page 450.

Philip Miller first described Euphorbia trigona in 1768 in The Gardeners Dictionary, eighth edition, n.° 3.