Bright red at Christmas time – and far more harmless than its reputation. It likes it bright, evenly warm and free of draughts. With patience and long nights, it even colours up a second time.

What it does for you

The poinsettia brings strong colour into winter – red, pink or white¹. The bright part isn't flowers, though, but bracts; the real flowers are the small yellow cyathia in the middle^2,3. It doesn't have to be thrown away: with care and long nights, it colours up again the next winter².

Origin & history

In the wild it grows from Mexico to Guatemala in seasonally dry tropical forests – as a shrub several metres tall^7,2.

The Aztecs called it Cuetlaxochitl⁸. In Mexico it later became the "Flor de Nochebuena", the flower of the Holy Night⁹. In 1828 the US envoy Joel R. Poinsett brought it to the USA² – hence the name poinsettia.

Caution

The white milky sap can irritate skin and mucous membranes and trigger allergies^1,5. NC State warns of mild to severe contact dermatitis and, if it gets into the eye, lasting damage to the cornea¹. The Bonn poison centre notes that the strongly irritant diterpenes were found only in the wild form and could not be detected in cultivated varieties⁵. As the sources differ, treat the sap as an irritant: wear gloves and keep it out of your eyes. Eaten leaves cause stomach ache, nausea and vomiting, very rarely drowsiness and dizziness^5,2. In cats and dogs it irritates the mouth and stomach, and they sometimes vomit⁶; isolated severe cases have been described⁵.

Care

Light. Bright, but without harsh sun^10,3; in winter it tolerates full light¹¹.

Water. Water as soon as the surface is dry – neither let it dry out nor keep it wet¹⁰. Open the wrapping at the bottom so water can drain³.

Temperature & humidity. An even 16–21 °C, away from radiators and draughts, not by a cold window at night¹⁰. Below 10 °C it drops leaves²; while it's coloured, keep it at 13 °C or more¹¹. Don't buy one from a cold display outside the shop¹⁰.

Soil, pot & repotting. Peat-free, loam-based soil with some bark¹¹. Cut it back to about 20 cm in early or mid-spring, and move it into a pot 5–10 cm (2–4 in) bigger in early summer².

Feeding. Don't feed while it's coloured³; after that, every two to three weeks from spring to early autumn².

Extras

How to get it to colour up again: it's a short-day plant. From mid-autumn, keep it completely dark for 14 hours every night for eight to ten weeks – under a cardboard box, say – and bright during the day^2,3. Even lamplight in the evening prevents the colouring³.