Houseplant of the Week: Crown of Thorns

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What makes Euphorbia milii, the Crown of Thorns, such an easy indoor plant to cultivate? It thrives in the conditions you find in most homes, adapting well to normal room temperatures (although it can withstand temperatures as low as 50 degrees). It doesn’t mind dry indoor conditions and will even forgive you if you miss a watering or two.

The one thing it does insist on is a little sunbathing. Your plant will be super happy in a sunny window where it gets about four hours of bright, indirect sunlight each day.

Caring for Your Crown of Thorns

  • Soil –Use a sandy, well-drained soil that is 2/3 cactus or succulent potting soil and 1/3 perlite or coarse sand. The soil should drain quickly to prevent root-rot.
  • Water – From late spring to early fall, water your plant well and then allow the top half of the soil to dry out before watering again. Reduce the amount of water when the plant is not producing new leaves and flowers, but never allow the soil to totally dry out. 
  • Fertilizer –Feed monthly when it is actively growing with a water-soluble fertilizer diluted to half the recommended strength.
  • Pests & Diseases – While the plant is pest-resistant, too much moisture can cause mildew or fungus on the plant.
  • Repotting – A Crown of Thorns plant needs to be repotted every two to three years.