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Indoor plant care

Crown of Thorns

Euphorbia milii

• LightCrown of Thorns needs bright direct light of 250 to 1000…
• WaterAllow Crown of Thorns soil to dry out completely between…
• ToxicityToxic to pets
• Mature sizeIt can reach 2 to 3 ft / 60 to 90 cm…

Crown of Thorns is a woody succulent shrub with thick, spiny stems. Small flowers are surrounded by colorful bracts that create most of the display. Its upright form and tolerance for dry soil make it manageable in sunny indoor spaces. Growers must place it carefully because both the sharp spines and irritating milky sap can cause injury.

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Care data checked 25 September 2026 · Dany · A-Z Plants

Light requirements

Crown of Thorns needs bright direct light of 250 to 1000 μmol·m⁻²·s⁻¹. Provide 6+ hours of direct sunlight each day.

• Place it within 2 ft / 60 cm of a south or southwest-facing window. Give it an unobstructed view of the sky.
• Too much light: sudden exposure can scorch tissue, so adjust the plant gradually.
• Too little light: stems weaken and flowering declines. Grow lights can support it in winter when daylight hours are shorter.
• A PAR meter or PAR meter app can measure PPFD in μmol·m⁻²·s⁻¹.

Watering

Allow Crown of Thorns soil to dry out completely between waterings. Check several depths with a knitting needle or chopstick. Do not add water while the lower part of the pot remains damp.

• Use room temperature rainwater, distilled water, or reverse osmosis water.
• Water deeply until liquid exits the drainage holes. Let all excess drain before returning the pot to a saucer or decorative planter.
• A container with drainage holes is essential. Wet soil can cause root rot and soft, failing stems.
• Water considerably less in winter, when active growth slows. Extreme drought may cause shriveling, dropped leaves, or crisp edges, but overwatering is the greater risk.

Soil

Use a specialty organic succulent potting mix with fast drainage. Crown of Thorns needs plenty of air around its roots and cannot tolerate dense, wet soil. The container must have drainage holes.

• DIY recipe: combine 2 parts coir, 2 parts coarse sand, and 1 part pumice.

Feeding

Apply an organic fertilizer formulated for succulents every 2 to 4 weeks from March to October. Follow the label strength and feed only after watering. Do not fertilize dry roots, and stop frequent feeding during winter when Crown of Thorns grows more slowly.

Temperature & humidity

Crown of Thorns prefers 65 to 90 °F / 18 to 32 °C. Keep it warm and away from cold drafts. Ideal humidity is 40%. Normal dry indoor air is suitable, while high humidity combined with wet soil can increase the chance of rot.

What to expect

Crown of Thorns takes around 2 to 3 years to mature. It can reach 2 to 3 ft / 60 to 90 cm tall and spread 1 to 2 ft / 30 to 60 cm. Growth is moderate, with stems becoming woodier as the plant ages.

Varieties & cultivars

• Euphorbia milii ‘Deshoei’: White flower bracts create a clean contrast with the thorny stems.
• Euphorbia milii ‘Rosea’: This form produces pink flower bracts.
• Euphorbia milii ‘Splendens’: The most common variety is known for vivid red flower bracts.
• Euphorbia milii ‘Dazzling Salmon’: Delicate salmon-pink bracts surround its small flowers.
• Euphorbia milii ‘Double Red’: Dense clusters contain double red flower bracts.