Euphorbia trigona is one of the most impressive succulents that can be grown indoors. This cactus-like, durable giant originated from exotic Madagascar and areas of Central Africa.
Euphorbia trigona is also known as Friendship cactus, African milk tree, Cathedral cactus, or Abyssinian euphorbia.
There is a legend that this plant should only be gifted and not purchased directly for yourself. This is why the plant will bring you happiness and prosperity into your home since it was pleasantly gifted to you one day. Hence the name Friendship cactus!
Plant Profile
African milk trees are fast-growing succulent plants that can grow up to 15 feet tall and can be used as a hedge outdoors. When grown indoors, this evergreen perennial can reach a height of nine feet and last for years.
It has characteristic upright, fleshy triangular stems with 0.5 inch long barbs growing on the edges. The small, 1 inch long, teardrop-shaped leaves grow between the thorns.
New shoots will appear along the stem edges. The shoots are lighter green, grow upright and parallel to the central stem, so the plant resembles a large chandelier in various shades of green.
Similar to all euphorbias, the African milk tree contains a poisonous white milky sap that leaks from any cuts in the leaves or stems.
Varieties: Green or Burgundy?
There are two common color varieties of the African milk tree, the green and burgundy version.
The green African milk trees have lighter v-shaped stripes on the stem and monochromatic dark green leaves.
There is also a cultivar in a deep burgundy color called E.T. Rubra or Royal Red. This stunning burgundy version of euphorbia, as a solitary plant or placed among green-leaved houseplants, will create dramatic visual contrast.
How to Care for Euphorbia Trigona
Whether it is a green or burgundy variant, caring for this modest, undemanding, and hardy plant will not take you much time. As with all succulents, the rule is simple: a lot of light and little water. African milk trees are great houseplants for beginners and for any outdoor area in zones 9b to 11 that receives little water.
Light: Sunny or Shady Spot?
The secret to the successful cultivation of African milk trees is provide a lot of light for this plant.
Ideal areas inside of a home are any location near a south facing window or by placing the plant directly in the windowsill. The African milk tree needs at least four hours of sunlight a day but can tolerate a partial shading position.
However, too much shade will cause the plant to grow slower and the green or burgundy color of the plant may lose its intensity.
Place a dull looking African milk tree in a sunny location to bring this plant’s colors back to its vibrant self.
Water: How Often Should I Water My African Milk Tree?
Another crucial factor for growing this plant is to rarely water this plant such as 2 or 3 times a month.
African milk trees are a succulent, which means that this plant does not need to be watered very often. In fact, succulents can store excess water in its stems and roots which allow them to withstand long periods of drought.
Keep this in mind when watering the plant.
The ideal watering schedule for an African milk tree is to water it once a week from spring to autumn and once every 15 days in the winter months.
Excess water and soaked substrate are the main enemies of this plant, so it is better to forget to water it from time to time than over watering it.
When To Water An African Milk Tree
Succulents are not plants that will show you when its time for more water with drooping branches or loose leaves like other tropical houseplants.
Follow these steps in order to determine when to water an African milk tree:
- Insert your index finger into the soil 2 inches deep
- Feel for moisture
- Water if the soil is dry
- Do not water if the soil is wet or moist
The recommended watering schedule of once every 7 days in summer and once every 15 days in winter is only a framework.
Feeling the soil allows you to adjust the watering regime to each plant because the rate at which water is consumed and evaporates depends on the overall environmental conditions.
Soil: What Soil Makes Euphorbia Trigona Happy?
To ensure the necessary permeability of the soil and prevent dangerous water retention around the roots, it is best to use ready-made mixtures for cactus and succulents.
Cactus and succulent substrates are light, nutritious, and porous, which are very important for an African milk tree.
If the local nursey or garden center does not have ready-made mixtures for cactus and succulents than you can make your own mixture.
This is the ratio I use to make homemade substrate for my succulents and cacti:
- One part soil or compost
- One part peat moss
- One part sand or gravel
If the substrate is not draining fast enough then add more sand or gravel to allow for the water to drain and dry out faster.
Repotting: How Often Should I Repot My Plant?
Another low maintenance feature of the African milk tree is that you do not have to transplant it often.
African milk trees only need to be transplanted when the roots fill the entire pot. Usually an African milk tree can be repotted into a slightly larger pot every 2 to 3 years.
Whenever you plant or replant African milk trees, use a pot with a drainage holes and make sure that the excess water can properly drain out of the pot.
What Container to Use for Euphorbia Trigona?
The African milk tree has a shallow and disproportionately small root system compared to the impressive size of the plant.
So the best container for an African milk tree are wide and shallow pots which will help provide more stability.
African milk trees will grow tall and wide with lateral arm-like stems which can cause the plant to tip over. This is why a wide pot is critical to ensure that your African milk tree does not tip over.
Humidity: Does Friendship Cactus Need Misting?
Most succulents come from dry areas with high temperatures. The combination of warmer temperatures with dry air makes succulents perfect for most homes.
In other words, you do not need to mist or worry about the humidity level for an African milk tree.
Unlike other tropical plants, African milk trees can be kept near a heat source and will not be affected by dry air such as by a radiator or air vent.
That being said, you can occasionally spray the African milk trees’ leaves with stale, lukewarm water. Spraying the plant’s leaves will help remove dust or other particles that can accumulate on the leaves.
Temperature: How Tolerant Is Euphorbia Trigona?
The optimal temperature for growing an African milk tree is between 55°F and 80°F throughout the year. Thankfully most indoor temperatures are in this range which make the African milk tree an ideal houseplant.
Similar to most succulents, African milk trees are not tolerant of low temperatures. The water stored in its stems at low temperatures turns into ice crystals which destroys the plant tissue.
The lowest temperature an African milk tree can tolerate is 40°F but only for a short interval.
On the other hand, high summer temperatures will not harm the African milk tree as long as it gets enough water.
Fertilization: Does African Milk Tree Need Additional Feeding?
Seasonal growth of almost 10 inches means that the African milk tree will benefit from fertilizer.
Liquid fertilizer with an equal proportion of nitrogen, phosphorus, and potassium will stimulate aboveground growth and root development. Thus, fertilizers with an NPK ratio of 10-10-10 will provide balanced feeding.
Nutrients can be added once a week with watering but the fertilizer needs to be diluted to 1/4 of the concentration specified in the manufacturer’s instructions.
Do not fertilize an African milk tree during the winter as the plant will be dormant and does not need extra nutrients.
Pruning: Should I Trim My African Milk Tree?
The word tree in its common name comes from the plants gigantic dimensions. One way to control its growth is by cutting off the top parts of the stem.
At first, the African milk tree might look strange after cutting the top part of the stem off.
However, the cut stem will recover, and in a relatively short amount of time, the cut will be completely invisible once the plant grows more.
Pruning will encourage the development of lateral shoots so the plant will not grow much taller. Not to mention the cuttings can be used for propagating new African milk trees.
Propagation: How To Propagate New African Milk Trees
Any lateral shoots or ‘arms’ detached from the parent stem can grow into a new great euphoria.
Follow the steps below to start new plants even if you do not have much horticultural experience:
- Use gloves and a sharp knife to separate the side shoots.
- Rinse the cut shoots with warm water to stop the milk sap from leaking.
- Dry the cuttings with a towel and leave them in the shade for the next two or three days.
- Wait until the cuts dry and scabs form. You can dip the cut shoots in powdered charcoal is speed up the scabbing process.
- Stick the cuttings with the formed scab into sand or perlite so that two-thirds of the cutting is above the substrate.
- Place the pot with the cuttings in a bright area but not in direct sunlight. Occasionally mist the substrate so that it does not dry out completely.
- The rooting process 10 to 15 days at a temperature of 65°F to 85°F, so it is best to propagate the plants in late spring or early summer.
You can transplant or move the cuttings to a different location once the cuttings have grown roots. Now you have successfully propagate an African milk tree!
Alternative Propagation: Horizontal Cut of Stems
If you cut off the tops of the euphorbia to control its height, you can use these cuttings to start new plants. Follow the same steps above.
The only difference is that the rooting process will take a little longer when starting an African milk tree from horizontal cuts of stems.
Typically the cuttings will root in two or three weeks because the plant needs more time to heal a relatively large surface cut.
Problems: What is Wrong With My Euphorbia Trigona?
Below are common problems and solutions that affect African milk trees.
Q: Why Does Euphorbia Trigona Have Yellow Dropping Leaves?
A: There are 3 primary reasons for yellowing and dropping leaves on an African milk tree.
1. Stress: If the African milk tree spends summer outside then it can drop its leaves when you bring the plant back into the house. Stress caused by a drastic change in conditions or transplanting conditions is likely to cause leaf rejection. But do not worry, the leaves will continue to grow when the plant gets used to its new environment.
2. Lack of water: Although African milk trees tolerate drought well, this does not mean that you cannot water the plant for long periods of time. When experiencing drought like conditions from underwatering, the African milk tree will use its reserves to maintain the stem as a vital part and discard the leaves. The logic is simple: if the conditions are right, the stem will produce new leaves, but the leaves cannot produce new stems, so they suffer as collateral damage from unfavorable conditions.
3. Excess water: Yellowing and subsequent leaf fall may be a result of excess water or poor soil permeability. Constantly moist substrate will negatively affect an African milk tree. The initial signs of excess water are yellow and lifeless leaves. If the African milk tree is left in wet or moist soil for too long then the roots may eventually rot. Root rot is recognizable since the rotten stems will no longer be able to stand upright.
Q: Why Does My Euphorbia Trigona Have Shriveled Stems?
A: Various names for the African milk tree often include the word cactus. However, the African milk tree is not a cactus and cannot survive for weeks without water. The shriveled stem clearly shows that the plant is drinking its last reserves of water. As soon as you water a shriveled African milk tree, the stems will fill up with water and return to their normal size.
Q: Why Does My Plant Have Ugly Brown Growths on the Stems?
A: Brown growths on the stems of an African milk tree are caused by too much bright direct sunlight. When an indoor African milk tree is placed outside, it needs a few days to get used to the brightness of the sun. Simply placing the plant in direct sunlight all day will cause the stem to turn brown. The same problem can occur if the African milk treet is placed near a south facing window where the sun’s rays are amplified by the glass and hit the plant for hours each day.
Pests: Do Pests Dare Eat A Toxic Plant?
Generally speaking, the African milk tree is a pest-free plant thanks to its poisonous milky sap.
However, aphids or spider mites can attack the plant, especially if the air in the room is dry.
Aphids and other household pests can be removed by using a homemade remedy or commercial pesticides. Personally I use the homemade remedy since it is safe to use around kids and pets.
Frequently Asked Questions
Q: How Toxic is Euphorbia Trigona?
A: The milky white sap secreted by the plant is quite poisonous and can cause serious issues if ingested. When the white milky sap comes in contact with the skin, it can cause irritation, itching, and burning. Ingesting the white sap can cause more serious problems such as vomiting and diarrhea. So it is a good idea to keep an African milk tree away from any pets or small children that like to play or nibble on plants.
Q: Do African Milk Trees Bloom?
A: Large, adult African milk trees growing freely in nature will bloom in late spring and early summer with tiny white or yellow flowers that appear on the tops of stems. These African milk trees are usually at least 20 years old and over 5 feet tall. Typically African milk trees that are grown indoors will not bloom.
Q: Is Euphorbia Trigona A Useful Houseplant?
A: Although NASA’s research did not include the African milk tree in the top ten air purifiers, it is still a plant that improves the air quality in its environment by eliminating microbes and bacteria. In the process of transpiration, the plant releases water into the air, which regulates the humidity level, and the oxygen it produces has a stimulating and relaxing effect. So African milk trees are great plants to have in the household.
Final Thoughts
In ancient times, the African milk tree was attributed to miraculous properties. Its milky juice was used to remove warts, while in India, for example, the dried root was used to treat snake bites.
Modern pharmacology has also recognized the beneficial properties of Euphorbia trigona, whose extracts are used in various medicaments — from those that treat skin lesions to stimulant antitumor treatments.
Even putting its medical benefits aside, the African milk tree is an undemanding exotic beauty that will liven up any home inside or out. With its green or burgundy coloration, this plant is a great addition for any home whether you’re a beginner or an experienced gardener.
