How to Grow and Care for an African Milk Tree Indoors

African milk tree is a succulent that resembles a cactus and is often grown indoors.

The African milk tree (Euphorbia trigona) goes by many names, including cathedral cactus, friendship cactus, and good luck cactus. Despite having multiple names containing the word cactus, it’s not a cactus but a succulent. Because this plant needs hot temperatures, the African milk tree only grows outdoors in USDA Zones 9–11, found in California, Arizona, Florida, and parts of Texas. Here’s what you need to know about growing this succulent tree.

Like most Euphorbias, the African milk tree produces milky sap that is toxic to pets and humans. It is safest to wear gloves and goggles when working with the plant.

Where to Plant African Milk Tree

If you live in USDA Zones 9–11, you can plant African milk trees outside. Choose an area that receives partial sunlight and has sufficient space for the tree to reach a height of up to 10 feet. 

Most people in the U.S. grow African milk trees indoors. Choose a south-, west-, or east-facing window that receives at least six hours of bright sunlight daily. 

How and When to Plant African Milk Tree

African milk trees can be brought home as houseplants at any time of year. Choose an area of your home that receives plenty of bright, direct light for at least six hours a day, and place it away from any hot or cold drafts.

African Milk Tree Care Tips

African milk trees thrive when they are properly cared for, receive adequate light, and aren’t exposed to cold temperatures.

Light

African milk trees do best in partial to full sun. Place them in an area outdoors that receives partial sunlight. If growing them indoors, put them where they receive bright, direct sunlight.

Soil and Water

These succulents can grow in many types of soil as long as it has good drainage. For heavy clay soil, add plenty of amendments, such as compost or manure, to ensure water drains well. The ideal soil pH is 6.1-7.8.

African milk trees are drought tolerant. When grown outdoors, they need more water in the summer. In the winter, water only when the top inch of soil is dry.

Indoor plants typically need water once a week. Ensure the soil dries out between waterings, and perform an easy soil check by inserting your finger about an inch into the soil to test for moisture before watering. Overwatering leads to root rot.

Temperature and Humidity

African milk trees need hot temperatures to grow outdoors. They don’t fare well in cold weather or frost for long. They can manage when the temperature drops as low as 32°F for a short time. These succulents do best when temperatures are between 60°F and 90°F. This succulent prefers moderate humidity of 40 to 60 percent.

Fertilizer

Fertilize an African milk tree twice a year—once in the spring and once in the summer—with a succulent fertilizer, following the instructions on the packaging.

Related: The 10 Best Fertilizers for Indoor Plants of 2024 to Help Your Greenery Thrive

Pruning

Pruning is important to maintain an African milk tree. Because they have shallow root systems and can grow tall, older plants can become top-heavy, making them candidates for falling over in some circumstances. In early spring, remove any dead or broken branches. Also, remove any branch that rubs on another or heads off in the wrong direction. To manage the plant’s height, cut the tallest branches above a leaf node.

Potting and Repotting

To grow an African milk tree indoors, choose a terra-cotta pot with a drainage hole and fill it with well-draining, good-quality succulent or cactus mix. African milk trees don’t require annual repotting, but if you see roots coming from the drainage hole, it is time to repot it.

Pests and Problems

Healthy African milk trees typically don’t have issues with pests or diseases.  Occasionally, mealybugs may make their home in this succulent. If you spot mealybugs, remove them using a paper towel or cotton swab with some rubbing alcohol or insecticidal soap. 

Overwatering this tree can lead to fungal and root issues. Some signs of overwatering include yellowing leaves, dropping leaves, and a squishy texture. If it’s underwatered, the skin can also dry out and drop leaves.

How to Propagate African Milk Tree

African milk tree is simple to propagate by taking a stem cutting.

1. Wear gloves to protect your hands, and consider goggles to protect your eyes. When cut, this plant releases a sap that can irritate the skin and eyes. 
2. Use a sharp knife or pruners that have been sterilized with alcohol.
3. Cut off a branch or an “arm” at the base of the plant. It will start oozing milky, white sap. 
4. Rinse the cutting with cold water until the sap stops. Then, place it in an area to dry out of direct sunlight until it develops a callus. 
5. When the callus has formed, place the bottom of the branch or arm about an inch into the soil of a pot. 
6. Place a layer of gravel over the soil to add weight and maintain the cutting in place. 
7. Put the pot in a warm area with bright, indirect light.
8. Roots typically form within two months. At that point, the plant is ready to be transplanted to a larger pot.

Types of African Milk Tree

There are two types of African milk tree plants: Euphorbia trigona, the green one, and Euphorbia trigona ‘Rubra’, a predominantly red one. They require the same care, although Rubra can handle a little more full sun.

Frequently Asked Questions

How fast do African milk trees grow?

When planted outside, this plant grows 1 to 2 feet annually until it reaches its maximum height of about 10 feet. When grown indoors, the plant typically grows to about half this height.

How do I make my African milk tree bushier?

If your African milk tree has only a single branch, cut off the end of the main branch to encourage it to grow new side branches. As those new side branches grow, repeat the process on them to promote new growth.

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