Euphorbia

Architectural, fast, and not a cactus

The African Milk Tree — Euphorbia trigona, in the reddish form usually sold here as Rubra or Red Milk Tree — grows as upright three-sided green columns edged with short paired thorns, with small teardrop leaves along the ridges that flush deep red in strong light. It looks like a cactus and it is not one. It is a Euphorbia, and that difference matters for one specific reason covered below.

It is also fast for a succulent. Given real sun it puts on visible height in a season and branches into a candelabra, which makes it one of the few plants in this catalogue that can genuinely fill a corner rather than decorate a shelf.

Light

The more the better. Bright indirect light keeps it alive; several hours of direct sun keeps it compact and brings out the red. In poor light the columns stretch thin, the red drains away to green, and the plant becomes top-heavy enough to lean. A south or west-facing spot suits it. If you move one from indoors to a balcony, do it over a week or two — a plant acclimatised to a room will scorch in full June sun.

Water

Only when the soil is completely dry, which through summer means roughly every two weeks and through winter means considerably less. Through the monsoon, when the air itself stops soil drying, leave it alone and check by weight rather than schedule. Soft, yellowing or wrinkling at the base of the column is overwatering, not thirst.

Soil and potting

Gritty, fast-draining mix in a heavy pot with a drainage hole. A tall plant in a light plastic pot topples, and the thorns make picking it up unpleasant. The soil mix guide has the ratio.

Good to know — the sap

Every Euphorbia bleeds a milky white latex when cut or broken, and this one is no exception. It is a serious irritant. On skin it causes burning and rash; in the eyes it can cause real injury, and people have needed hospital treatment after rubbing an eye while pruning one. Wear gloves, keep it well away from children and pets, and wash immediately if you get sap on you. This is the single most important thing to know about the plant, and it is why we would not recommend it as a gift for a house with toddlers. The cactus care guide covers the rest of its seasonal routine.