Crown of thorns care guide

Crown of thorns is a thorny succulent shrub that blooms almost all year with small clusters of red, pink, yellow, or white bracts. It loves sun, handles dry air, and forgives missed waterings. Handle it with gloves. The thorns are sharp, and the milky sap stings.

Light

Give it your sunniest window. A south or west window is best. More sun means more flowers.

In low light, it stops blooming and drops leaves.

Water

Water when the top half of the soil is dry. Water until it drains, then empty the saucer.

It holds water in its stems, so it handles dry spells. A plant left dry too long drops its leaves to save water. They grow back once it gets a drink. Soggy soil rots the roots. Read how to tell if a houseplant is overwatered or underwatered.

Soil and potting

Use cactus and succulent mix. A terracotta pot with a drainage hole helps.

Repot every two to three years in spring. Wear thick gloves, or wrap the stems in a folded towel. See how to repot a houseplant step by step.

Humidity and temperature

Dry indoor air is fine. Keep it between 16 and 29°C (60 and 85°F), away from cold windows. It can spend summer outside in sun.

Feeding

Feed monthly in spring and summer with a balanced liquid fertilizer at half strength.

Pruning

Prune in spring to shape it. Cut just above a leaf. Wear gloves and eye protection. The milky sap stings skin and can damage eyes. Rinse cuts with cool water to stop the sap, or dab them with a paper towel.

Propagation

1. Cut a stem tip 8 to 10 cm (3 to 4 in) long.
2. Rinse the cut end in water until the sap stops.
3. Let it dry for a few days, until the end calluses.
4. Push it into dry cactus mix. Give it a little water once roots form, in a few weeks.

Problems

What you see	Most likely cause
Leaves drop	Too dry, too cold, or not enough light
No flowers	Not enough sun
Yellow leaves, soft stems	Too much water
Long, leggy stems	Not enough light
White, cottony spots	Mealybugs

Pests

Mealybugs and scale can hide among the thorns. Dab them with rubbing alcohol on a cotton swab.

Pet safety

The ASPCA lists crown of thorns as toxic to cats and dogs. The milky sap irritates the mouth and stomach and can cause vomiting. It also irritates skin and eyes. The thorns can injure a curious pet. Keep it well out of reach.

Varieties

• Classic crown of thorns has small, red bracts.
• Thai hybrids have large, bold bracts in pink, yellow, cream, and red.
• Dwarf types stay small and bushy.
• Some types have yellow or white bracts.