Crown of thorns care guide
Euphorbia milii
Quick answer
Water your crown of thorns when the top 5 cm (2 in) of soil feel dry. In summer that’s typically every 8 to 12 days.
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- Light
- Bright / direct light
- Typical interval
- Every 8 to 12 days · summer
Every 16 to 24 days, sometimes less · winter - Climate
- 18–29 °C (64–84 °F)
- Humidity
- 30–50%
- Pet safety
- Toxic to cats and dogs
When and how to water
5 cm (2 in)
- Summer · Jun–AugEvery 8 to 12 days
- Winter · Dec–FebEvery 16 to 24 days, sometimes less
Use room-temperature water and let any excess drain. Never leave the pot sitting in standing water.
Adjust the timing for the light at the plant, the pot’s size and material, and the humidity indoors. Terracotta dries faster than glazed ceramic.
Light and placement
Bright / direct light
Crown of thorns needs several hours of direct sun. Turn the pot every week so it grows evenly. Place it directly in front of a south- or southwest-facing window.
Feeding
Feed your crown of thorns every 30 days while it’s actively growing. Use a liquid houseplant or cactus fertilizer, diluted as its label directs, and only on soil that’s already damp.
When growth pauses, skip the fertilizer and let it rest.
Temperature & humidity
Climate18–29 °C (64–84 °F)
Humidity30–50%
During leafy growth, aim for 18–29 °C (64–84 °F). For routine indoor care, keep it above about 10 °C (50 °F) and avoid cold drafts. This is a care guideline, not an exact damage threshold. Cooler overwintering depends on the species and its rest conditions.
It does best at 30–50% humidity. It doesn’t need misting.
Toxic to pets?
Yes. Keep it out of reach.
Wear gloves when you cut or repot it. Keep the sap away from your eyes and skin, and wash your hands afterwards.
Pet-safety information in the JungleBook uses NC State Extension Plant Toolbox where available. It is reference information, not veterinary advice. NC State Extension Plant Toolbox lists the whole Euphorbia genus, so this applies to every Euphorbia species, including this one.
Pet-safe alternatives with similar light
Common questions
How often should I water a crown of thorns?
Water your crown of thorns (Euphorbia milii) when the top 5 cm (2 in) of soil feel dry. In summer, that’s typically every 8 to 12 days. In winter, slow down to every 16 to 24 days, sometimes less.
Sources5 references
- Royal Botanic Gardens, Kew: Plants of the World OnlineAccepted name · classification · native range
- North Carolina State University Extension Gardener Plant ToolboxDescription · indoor care · cyclical leaf drop · insects, diseases, and other plant problems
- University of Wisconsin–Madison Division of ExtensionLight · watering · fertilizer · temperature · flowering · disease and hybrid context
- University of Florida IFAS Extension: Gardening SolutionsFull sun · container drought tolerance · frost protection · milky sap and spines
- Pet Poison HelplineScientific name · oral and gastrointestinal signs · dermal and eye irritation
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