The exotic African Milk Tree, Euphorbia trigona

Euphorbia trigona , or African Milk Tree, is known for rapid and enthusiastic growth. Growing up to six to eight feet tall, it is a rugged, easy-care plant with thorns! The plant features three-sided stalks with spines along its edges and cactus-like branches, and is appropriate in a variety of landscaping and gardening uses.

Many people think of African Milk Tree (Euphorbia trigona) as a cactus. It is grown as an indoor plant and used as an attractive addition to cactus and succulent gardens in warmer areas.

Why Isn’t Euphorbia trigona A Cactus?

African Milk Tree is considered a succulent because it has leaves. Cacti (with the exception of Christmas and Easter Cactus) do not grow leaves. The leaves of the African Milk plant are small and short-lived. They grow along the ridges that make up the corners of the plant’s rectangular stems. Thorns also emerge from these ridges.

The thorns grow in sets of two, and single leaves emerge from between them. When grown outdoors, the plant may produce small white or yellow flowers. Indoors, it is unlikely to bloom.

Why Is The Euphorbia trigona Called A “Milk Tree”?

The African Milk Tree is a member of the Euphorbaceae family. All of these plants exude a poisonous white sap when cut or broken.
For this reason, it’s a good idea to keep them out of the reach of kids and pets and to keep your skin and eyes well-protected when pruning, repotting or otherwise handling the plant. The sap can cause serious skin and eye irritation on contact, as well as severe gastric distress if ingested. [source]

Is Euphorbia trigona Really A Tree?

These big succulents outdoors are tree-like. They can grow as high as nine feet, and grow in a characteristic “candelabra” shape giving them the appearance of a tree. It may also explain some of the plant‘s common names – Candelabra Euphorbia or Cathedral Cactus.
You can control the plant’s growth somewhat by cutting or breaking off stems, which you can plant in their own pots, using a light, sandy soil to grow more “trees” to share with friends.

African Milk Tree Propagation

Propagation of this hardy succulent couldn’t be easier. Visually survey your plant before you begin and decide which new stems or sections you want to reduce.

Be sure to put on rubber gloves and protect your eyes with goggles, then just break or cut sections of the parent plant. Sections used for rooting should be about three or four inches in length. Luckily, this operation turned out alright, but it’s easy to see that these plants produce copious amounts of potentially dangerous sap.

When you take cuttings, be sure to have a damp cloth on hand to wipe up weeping sap. Wear gloves, goggles and long sleeves, and be careful not to let the sap come in contact with your skin or eyes. Once you’ve taken cuttings, lay them on paper towels, newspaper or some other disposable, absorbent material.

Allow the sections to dry out and harden off for a week in a cool, dry place, out of direct sunlight. After your cuttings have hardened off, plant them in an airy, sandy, well-draining soil mixture that is not too fertile. You needn’t worry much about pH level as Euphorbia trigona grow in acidic, neutral or alkaline soil.

Water when you plant the cuttings, keep the soil lightly moist until signs of rooting and growth appear. At this point, you can reduce watering and begin treating the cutting as an adult plant.

Euphorbia trigona Care

Once established Euphorbia trigona is an easy care plant. It’s best to provide lots of sunlight and/or artificial light. If you’ve grown Euphorbia milli (Crown of Thorns) you’ll do fine. These plants can do very well (like Euphorbia milli Crown of Thorns) as houseplants year-round in medium light settings and normal household temperatures.

By gradually transitioning the plant to more sun you can enjoy the African milk tree in the great outdoors during the spring and summer.
Transition the plant gradually, so it acclimates to more sun, air movement and temperature fluctuations. Choose a sheltered area that gets filtered sunlight or part sunlight for potted and container plants.

If you live in a semi-tropical or desert area where temperatures will unlikely to drop below 50 degrees Fahrenheit and never freeze, plant Euphorbia trigona directly in the ground. In this case, choose a fairly sheltered location that receives full sun or part shade.

As a Container Plant

If you need to move your Euphorbia trigona outdoors or repot as a container plant, it’s best to do so in the springtime. You can groom the parent plant and take cuttings while making the transfer. Remember to wear protective gear to prevent accidental stabbings and sap contact.
Grooming is easy with these plants. Just break or cut off stems that don’t seem to fit in. Remove any branch that protrudes and might break off accidentally as people walk past.

If accidental contact with sap does occur, be sure to wash well immediately to avoid irritation. If sap gets in eyes, it should be flushed out with running water, and a visit to the emergency room would not be overly dramatic. [source]

Water: Because these plants are succulents (not cacti) they do not tolerate complete drought. Keep the soil very lightly moist during the growing season (spring and summer).

If the top couple of inches of soil feel dry, a deep watering is in order. Just be sure the plant does not stand in water as this can lead to root rot.
Fertilizer: Provide a light feeding of balanced water-soluble fertilizer monthly during the spring and summer. Reduce watering and do not fertilize at all during the cooler months (fall and winter).

How To Deal With Common Pests and Disease

Euphorbia trigona is relatively hardy and resistant to disease and pest, as long as it has good care. Avoid waterlogging the soil and providing the plant with good sunlight and air circulation. This will go a long way toward preventing problems. Weakened plants may be susceptible to:

Mealybugs

If you see cotton-like threads forming on the plant, wipe them off with a paper towel soaked in rubbing alcohol. If you have a massive infestation, wipe the mealybugs off and spray the plant with a natural insecticide, such as a Neem oil spray solution.

Plant Scale

Scale insects: These tiny insects are covered by a nearly impenetrable brown shield. This makes it difficult to remove them.
Like the mealybug wipe them off firmly with a paper towel soaked in rubbing alcohol. If this doesn’t work, scrape them off gently with a knife blade. A Neem oil solution can be used to assure they are gone and prevent their return.

Fungal Infection Cork Disease

Cork disease is a fungal infection. Patches of cork-like material on the stem is an indication of overwatering and/or soil that is too rich. If you’ve kept cuttings and have replacement plants, you are best to dispose off of the diseased plant. To save it, prune the plant with a very sharp, sterilized knife or shears to completely remove the damaged areas and dispose of them in the trash (not the compost heap).

Paint the cut areas with a plant fungicide. Repot the plant into a cactus soil and keep it in a consistently warm and airy location.
Reduce watering. You may not be able to save the plant, but keeping it dry, warm and well-ventilated will give it the best chance of survival.

Rot or Fusarium Wilt

Fusarium wilt and rot is another fungal infection that comes from the soil. If your plant displays soft, reddish patches around the base of the stem, suspect fusarium rot. Most of the time, it is fatal and disposing of the plant, pot and all is the best solution. If you keep the container, be sure to sterilize it before using it again. If you must save the plant, follow the steps outlined for cork disease. [source]

Hardy Euphorbia trigona is Virtually Problem-Free

All-in-all, caring for African Milk Plant is amazingly easy. Begin by choosing a healthy plant (or cutting) with no soft spots or signs of pests.
If you acquire a potted plant, check to be sure the root system holds the plant into the pot firmly. Make sure the plant has not been sitting in water.

If you begin with a well-cared-for plant and continue to provide it with well-draining soil that’s not too rich, lots of sunlight and an airy setting, it should grow well and provide you with lots of healthy cuttings for many years.