Crown of thorns
Sources last read 14 September 2026.
Forgiving Among the more tolerant plants here.
Also called Christ plant, Christ thorn and christplant.
Crown of thorns is toxic
- Not assessed for cats. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Not assessed for dogs. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Toxic to people. People and pets: irritates skin and eyes; harmful when eaten. Use gloves and protective gear when handling it. RHS
What the sources say about its care
- Light
- Full sunRHS · read 13 September 2026
- Water
- Well-drainedRHS · read 13 September 2026
- Humidity
No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.
Most foliage plants prefer more humidity than a heated room gives; succulents are named as an exceptionPenn State Extension · read 13 September 2026- Temperature
How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.
H1B — 10–15°C 10–15 °CRHS · read 13 September 2026- Soil
- Chalk, Loam, Sand; pH Acid or Alkaline or NeutralRHS · read 13 September 2026
- Toxic to cats
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Toxic to dogs
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Harmful to people
- People and pets: irritates skin and eyes; harmful when eaten. Use gloves and protective gear when handling it.RHS · read 13 September 2026
How it usually goes wrong
- Leaves soften and curl inward
Posture goes before colour. A thirsty crown of thorns looks deflated rather than diseased, and the compost has shrunk away from the side of the pot.
Its source describes well-drained soil. Below that the cells lose pressure, and pressure is what holds a leaf out straight.
Telling it apart: Lift the pot. A plant that is light and sagging is thirsty; one that is heavy and sagging is not.
RHSCrown of thorns soft or mushy stem: causes- Pale dry areas across the upper leaves only
Affected tissue goes pale and then papery, and the boundary follows where the light falls rather than the shape of the leaf.
Its source names full sun, yet a leaf grown in lower light has thinner tissue than one grown in sun, and it scorches if moved into strong light in one step.
Telling it apart: Whether the patches grow. Scorch is done once it happens; a leaf spot keeps spreading.
RHSDiagnose yellowing leaves on this Crown of thorns- Swollen, darkening leaves that come away at a touch
A leaf of the crown of thorns that should be firm gives under light pressure and stays dented, and those beside it follow within days.
Its source describes well-drained soil. Past that, a plant built to survive drought has no mechanism for shedding the excess, and the tissue breaks down rather than simply looking unwell.
Telling it apart: How recently it was watered. Soft tissue within a week of watering points at the water; soft tissue in dry compost points at cold.
RHSDiagnose leaf drop on this Crown of thorns
Not sure which it is? Ask the diagnosis questions for Crown of thorns.
Routine care
- Watering
- During growth, water sparingly and feed monthly with a low nitrogen liquid fertiliser.RHS · read 13 September 2026
- Feeding
- While growing, water sparingly and give a low-nitrogen liquid fertiliser each month.RHS · read 13 September 2026
- Propagation
- Stem cuttings work, but allow the sap to dry before setting the cutting in growing medium. It is easy to propagate and share, though named cultivars are rarely sold.NC State Extension · read 13 September 2026Sow seed at 15 to 20°C once ripe.RHS · read 13 September 2026
- Pests and diseases
- Usually free of pests. Diseases: grey moulds can occur.RHS · read 13 September 2026
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Photographs
About the plant
Euphorbia milii, the crown-of-thorns, Christ plant or Christ's thorn, is a species of flowering plant in the spurge family, Euphorbiaceae, native to Madagascar. The epithet commemorates Baron Milius, once Governor of Réunion, who introduced the species to France in 1821.
From Wikipedia, CC BY-SA 4.0 · read 13 September 2026
- Native range
- MadagascarWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026MadagascarNC State Extension · read 13 September 2026MadagascarRHS · read 13 September 2026
- Climate
- desert or dry shrublandWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026
- Growth form
- semisucculent subshrub or shrubWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026Shrub, Succulent; habit dense, multi-stemmedNC State Extension · read 13 September 2026Bushy (evergreen)RHS · read 13 September 2026
- Size
- Height 36–72 in; width 18–36 inNC State Extension · read 13 September 2026Height 0.5-1 metres; spread 0.1-0.5 metres after 10–20 yearsRHS · read 13 September 2026
- Flowering
- Flowers gold/yellow, green, red/burgundy; blooms in fall, spring, summer, winterNC State Extension · read 13 September 2026Flowers red in summer; yellow in summerRHS · read 13 September 2026
- Uses
What sources record people using this plant for. A traditional or medicinal use listed here is a record of use, not advice to eat it or treat anything with it.
Toxic if eaten.NC State Extension · read 13 September 2026
Common problems with Crown of thorns
Other Euphorbia
African Milk BarrelSourced care, difficulty not yet judged
African Milk TreeSourced care, difficulty not yet judged
African MilkbushSourced care, difficulty not yet judged
African MilkbushSourced care, difficulty not yet judged
African SpurgeSourced care, difficulty not yet judged
Breathless™ EuphorbiasSourced care, difficulty not yet judged
More of the Euphorbiaceae family
Bristly CopperleafSourced care, difficulty not yet judged
Buddha Belly PlantSourced care, difficulty not yet judged
Candelabra CactusSourced care, difficulty not yet judged
ChureeSourced care, difficulty not yet judged
CooperleafSourced care, difficulty not yet judged
Corncob CactusSourced care, difficulty not yet judged
Plants with similar care
Aloe veraMushy tissue at the base of the aloe vera
Baby rubber plantLeaves turn glassy from the stem outward
Bunny ears cactusLeaves go soft and slightly see-through
HoyaDry scorched spots after a move into a sunnier spot
Jade plantPale dry areas across the upper leaves only
Mexican snowballPale dry areas across the upper leaves only
Sources
- ASPCA · read 13 September 2026
- Kew WCVP · read 13 September 2026
- NC State Extension · read 13 September 2026
- Penn State Extension · read 13 September 2026
- RHS · read 13 September 2026
- Wikipedia · read 13 September 2026
What this does not cover
The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.
Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.
If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.