Christplant (Euphorbia milii)

How much light does a Christplant need?

Full sun outdoors is the best light for this plant, at least six hours of direct sun a day. It can also grow in part shade, though full sun is the preferred condition for this species. Both full sun and part shade are listed as suitable light levels for it outdoors.

• Light: Full sun and part shade (full sun preferred)^1,2

How often to water a Christplant

Give this plant water that ranges from dry to medium, not a constant moisture level. Water deeply, then let the soil dry out before you water again. This dry-to-medium range suits a plant that does not want to stay wet all the time. Avoid letting it sit in soggy soil between waterings.

• Water: Dry to medium²

Best soil for a Christplant

This plant needs soil that drains well when grown outdoors. It also tolerates soil that is occasionally dry rather than evenly moist. Well-drained and occasionally dry are the two soil conditions recorded for this species. A constantly wet mix is not one of them. Choose a planting spot or pot that lets water drain through instead of pooling. This plant is not documented as needing consistently moist soil outdoors.

• Soil drainage: Well drained and occasionally dry²

Hardiness and temperature

USDA zones 9a through 11b mark this plant's outdoor hardiness range. It does not tolerate wet, cold soil, and it dislikes temperatures below 35.6°F (2°C). This plant does well in low humidity rather than high humidity. Zones below 9a fall outside its documented hardiness range. The coldest temperature it is documented to tolerate is 35.6°F (2°C). Humidity levels on the higher side are not what this plant is documented to prefer.

• Hardiness: Zones 9a–11b¹
• Minimum temperature: 35.6 °F (2 °C)¹

Fertilizing a Christplant

Spring and summer are when to fertilize this plant, lightly and just once a year. Use a balanced fertilizer rather than a strong or frequent feed. Outside of spring and summer, this plant is not documented as needing fertilizer. A light touch is enough, rather than a heavy feeding schedule.

• Fertilizer: Light, once a year (Mar–Aug)²

Pruning a Christplant

Prune this plant lightly to shape it. Light shaping also helps keep its size in check. At maturity, this plant can reach about 5 ft (1.52 m) tall and 3 ft (0.91 m) wide. Light pruning keeps its shape and size under control as it grows.

• Pruning: Light shaping²

How to plant a Christplant

Plant this species outdoors in USDA zones 9a through 11b. Space plants about 3 ft (0.91 m) apart, matching their mature spread. It can also grow up to about 5 ft (1.52 m) tall at maturity. This species is native to Madagascar. In the continental United States and Puerto Rico, it is classified as introduced rather than native. Replant it in spring or summer, when it is growing vigorously.

• Hardiness: Zones 9a–11b¹

Winter care

In winter, protect this plant from temperatures below 35.6°F (2°C). Outdoors, that limit applies in zones cooler than its hardy range of 9a to 11b. Indoors for winter, it succeeds in heated homes, since it does well in low humidity. Below zone 9a, this species does not have a documented outdoor winter hardiness. Where winters dip below 35.6°F (2°C), bring the plant indoors or grow it in a container instead.

• Hardiness: Zones 9a–11b¹
• Minimum temperature: 35.6 °F (2 °C)¹

How to propagate a Christplant

You can propagate this plant from seed, stem cuttings or grafting. Stem cuttings are one way to start a new plant. Growers can also use a technique called V cleft grafting to propagate it. Seed is a third documented method for growing new plants of this species. No single method is marked as the preferred one among the three documented here.

• Propagation: Seed, stem cuttings and grafting^1,2,2

Common problems

Scale, mealybugs, thrips and spider mites are the insect pests recorded on this plant. Leaf spot, stem rot, root rot and botrytis blight are its documented diseases. In the Midwest, mealybugs are the most common of these pests, while spider mites, scale and thrips occur less often.

• Common pests: scale, mealybugs, thrips and spider mites^1,2
• Common diseases: leaf spot, stem rot, root rot and botrytis blight¹

Questions and answers

Is Euphorbia milii toxic to cats and dogs?

Crown of thorns is toxic to both cats and dogs. In cats, it is documented to cause mild irritation to the mouth and stomach.

What light does crown of thorns need outdoors?

Give it full sun outdoors, with at least six hours of direct light a day. It also tolerates part shade, though full sun is preferred.

How can you propagate Euphorbia milii?

You can propagate this plant from seed, stem cuttings or grafting. Stem cuttings are one way to start a new plant. Grafting, specifically a technique called V cleft grafting, is another documented method.