Crown of thorns care: watering, light and repotting
Also called christ plant, christ thorn · Euphorbia milii · Euphorbiaceae family
21 d in winter
How often to water the crown of thorns?
Allow about 10 days between waterings in spring and summer, and 21 days in autumn and winter, when growth slows down. These rhythms apply to a room with its favourite light: in a darker room the plant drinks less; in a brighter one, it drinks more.
Flowers almost all year in full sun. Irritating sap and spines: keep it out of reach.
What light does it need?
The crown of thorns loves the sun: a south- or west-facing window suits it, ideally less than 3 ft (1 m) from the glass. Without enough light, the stems stretch and growth slows down.
Repotting and fertiliser
Repot every 3 years, ideally in April, into a pot only slightly bigger than the last one. As for fertiliser, from April to September, feeding every 30 days is enough; the rest of the year, let it rest.
Adult size: 1–2 ft (30–60 cm).
Toxic to pets and children. Keep this plant out of reach and, if it is eaten, contact a vet or a poison control centre.
Common problems
Falling leaves
Cause: Cold or too much water. What to do: Keep it above 59 °F (15 °C) and let it dry out.
Few flowers
Cause: Not enough sun. What to do: Put it on a south-facing windowsill.
Frequently asked questions
How often should you water the crown of thorns?
About every 10 days in spring and summer, and every 3 weeks in autumn and winter, in a room with its favourite light. The darker the room, the longer you wait between waterings. Before watering, check that the top inch of soil has dried.
Where should you put the crown of thorns?
The crown of thorns loves the sun: a south- or west-facing window suits it, ideally less than 3 ft (1 m) from the glass. Without enough light, the stems stretch and growth slows down.
Should you mist the crown of thorns?
There's no need: indoor air suits it. Wetting its leaves for no reason can even encourage disease.
When should you repot the crown of thorns?
Every 3 years, ideally in April, or sooner if roots come out of the drainage hole. Choose a pot only slightly bigger, 1 to 1.5 in (2 to 4 cm) wider, always with a hole in the bottom.
Cats, dogs, children: is the crown of thorns safe?
The crown of thorns is toxic to pets and to children if eaten. Keep the plant out of reach and, if it's eaten, call a vet or a poison control centre.
Is it an easy plant to care for?
Yes: the crown of thorns forgives a missed watering and adapts well to the home. A good plant to start with.
These are guidelines for an indoor plant in a temperate climate. Trust the soil too: a finger pushed an inch into it will tell you whether it's thirsty.