Crown of Thorns Plant Leaves Turning Yellow. Reasons And Solutions!

Crown of thorns plant, Euphorbia milii, Christ plant or Christ thorn as you call it, is a flowering decorative succulent grown both indoors and outdoors. Crown of thorns plant has thorny stalks, bright green leaves, and colorful

 flowers that bloom throughout the year, that’s why it is a truly everblooming plant.

You have to properly care for this plant to prevent your crown of thorns plant leaves from turning yellow.

Photo: Wikimedia Commons

Crown Of Thorns Plants Leaves Turning Yellow

 It is common to see Crown of thorns plants leaves turning yellow. The bright colours of the crown of the thorns plant can lighten if the plant is not properly cared for. The leaves start turning yellow and fall off faster than usual if something is amiss in their environment.

Reasons of yellowing of the leaves

Deficiency of water

Generally, succulent plant leaves wilt and become yellow because of the deficiency of water.  Sudden temperature changes, poor soil quality, etc. are the stress factors responsible for yellow leaves. Underwatering turns the leaves yellow followed by shriveling and wilting.


 Overwatering is a major problem with the crown of thorns and often results in spongy stem, leaf loss, and failure to bloom along with yellow leaves. It doesn’t require much water being a desert plant as too much moisture can damage the cells of the leaves. Water your crown of thorns once a week and let the soil dry between waterings. Watering it more or less will also depend upon factors like the size and location of your plant.

Lack of sunlight

Another factor responsible for yellow leaves is the lack of sunlight as they flourish best in full sun and higher temperatures. 

In winters, protect these plants from frost by keeping them inside or in a shelter, otherwise, the leaves may become yellow and the plant will not survive.

Not getting enough nutrients

Sometimes lack of nutrients can also turn your crown of thorns plant leaves yellow and high-phosphorus can help mature plants to blossom. 

How To Prevent Crown of Thorns Plant Leaves Turning Yellow?


Follow a proper care schedule to prevent your crown of thorns plant leaves from turning yellow. It is necessary to water and fertilize your plant regularly. There are  certain things that you should do to keep the leaves of the crown of thorns from turning yellow: 

  •  Regularly water your plant for good plant health. Mostly, watering once a week is sufficient.  Restrict watering when it starts to get cold in winters.
  • Don’t add fertilizers during winter months and use the right potting soil, also make sure that your crown of thorns is never overwatered. Add pumice to the soil to provide drainage for the crown of thorns, also add components like sand or perlite to your soil.
  • Drainage should be proper so that the roots are not clogged with water. Peat moss can be added to give both nutrition and texture. The plant will only take the water it needs to survive.

Giving your crown of thorns plant proper care will take it a long way. Avoid yellowing by

providing your plant the right amount of moisture, sunlight, and nutrients.

Crown Of Thorns Plant Life Span

Crown of thorns is a tough perennial with substantial gray spines and oval leaves that fall as they age. The expanded, branched stems can attain a height of more than seven feet ( two meters ), but the potted plants are much smaller. The small flowers bloom in paired clusters and are enclosed in two bright light red, deep red, or yellow bracts. 


The crown of thorns is widely grown succulent as an ornamental plant since it blooms throughout the year and it is native to Madagascar and grows well in the tropics. It is a low-maintenance plant, making it a good choice for succulent lovers. 

Euphorbia milii got the Royal Horticultural Society’s Award of Garden Merit in 1993 for its outstanding features.


A healthy crown of thorns plant has emerald green leaves and flowers in different colours like white, pink, red, and even yellow that bloom throughout the year. Although it is a small succulent, a healthy crown of thorns can grow up to two to three feet tall.

Euphorbia milii is a slow growing, evergreen succulent known for its piercing, an inch-long thorns found all over the stem. The thick stems store enough water to survive in drought. Euphorbia milii is a salt tolerant succulent.

The narrow, ovoid shaped, glossy leaves whorled on the stem fall off naturally as the plant gets older.


This gives a skinny display in older plants – strikingly delightful for your living room or office.

Crown of thorns is known for its spectacular blooms, which are not real flowers in the actual sense, but leaf-like red bracts present at the shoot tips. These distinct, bell shaped bracts surround the real yellow flowers.

Crown of thorns bloom mostly between spring and late summer but in favourable conditions, the plant can produce flowers throughout the year.

A Crown of Thorns plant likes warm weather and grows well in temperatures ranging from 15.6°to 35°C (60°- 95°F). A Crown of Thorns plant will start losing leaves if the temperature goes down to 12.8°C (55°F).

Is Crown of thorns a poisonous succulent ?

Like the other members of the Euphorbiaceae family, the crown of thorn has sticky, milky sap which is toxic and may cause dermatitis and  partial blindness if it goes into the eyes. All parts are toxic if ingested so keep it away from pets and toddlers. Also be careful of its sharp spines.

 Propagation of Crown of Thorns

Propagation of the crown of thorns is carried out by stem cuttings which is very easy and success rate is also high. 

Take a sterilized blade or knife and snip off a younger branch at the point where the trunk and the branch meet. As you cut the branch, some white sap starts dripping from the cuts. You can stop this by immersing the cuts in warm water to avoid the sap from running excessively.

Keep your cuttings in a dry place, on a newspaper or a paper towel to let them dry and callus. It will take two to three days.

Take a small pot and fill it with a well-drained potting mix. Cacti commercial mix is a good option. Soil should be slightly moist because if it is too dry, the roots may not develop and the cuttings may rot if the soil is wet. If you want the roots to develop faster, dip the cuttings in a rooting hormone. Put the cuttings in the moist potting mix and keep them in a sunny area. Do not water it for several weeks until the cuttings start developing roots. You can check this by gently pulling the plants and find if there is some resistance.

The plant will be set up in a month and it will begin to grow. Start watering it lightly now.

Crown of Thorns Problems

Crown of thorns have to encounter some issues like other succulents. Some of the Crown of thorns problems are:

Stem rot

A common problem affecting crown of thorns plants is stem rot and two fungal diseases are responsible for the stem rot that develop easily in moist and humid conditions. You can avoid the development of these diseases with proper care of the plant.

Rhizoctoria Fungus

All soils contain many species of fungus of the Rhizoctoria genus.   

Humidity and excessive soil moisture are the two factors that lead to the development of fungal diseases, especially Rhizoctoria. The Rhizoctoria fungus manifests itself on the stems and roots of the mature Crown of thorns plant. Plants start drooping and become unhealthy. Early stem wounds develop near the soil line due to excessive moisture creating the misconception that the areas are wetted. As the disease grows, the wounds turn brown or black, infecting the whole stem.

Fusarium Fungus

There are many strains of fungi of the Fusarium genus. This fungus invades all parts of the infected plant, not only the stem or roots. Wet, slushy, and sunken stem lesions develop all over the stem that is enclosed by a purple border near the soil line. This fungal infection occurs in cut or pruned stems. The development of Fusarium starts with what looks like dry rot. Infected areas become pulpy, expanding to the base of the stem, soon the entire plant stem gets infected.

Prevention and Control

  1. A soil-borne disease, Rhizoctonia  can remain dormant for many years. To eradicate Rhizoctoria while planting or transplanting crown of thorns plants, use a sterile growing medium and wash and sterilize the pots and plant tools.
  2. Don’t water the plant stems or leaves and water the plants less often, but thoroughly. To find if the plants need water, put a finger deep into the soil. Water the plants only when the soil is dry enough from the surface to the tip of the finger. 
  3. To stop the growth of Fusarium, get rid of the infected plant. Or the disease can affect all the plants by invading plant tissue via lesions or wounds.

Crown Of Thorns Plant Leaves Curling

 Some of the reasons for the crown of thorns plant leaves curling are :

  • When the plant needs water, the leaves start curling but don’t wait for this, allow only an inch or so of the topsoil to dry out. If the root ball starts drying, the leaves will start falling but it can happen due to overwatering as well. Being a little alert will help you in differentiating both. 
  • When you water, do it effectively. Soak the soil completely and make sure it drains completely. Lesser watering in the cool season is good for plants after the flowers drop off.
  • Porous soil is good for Crown of thorns Plants as it drains well. They can flourish in poor soil provided it is not soggy. Rich soils can enhance leaves, but not flowers and they also encourage rot. Cactus potting soil is also good for Crown of thorns and you can also combine equal parts of loam, sand and perlite to make a potting mix.
Photo: / {Phosphorus deficient Crown of thorns}

Best Fertilizer For Crown Of Thorns

When you plant a Crown of thorns, fertilize it first with a slow release, full-strength liquid fertilizer. Afterwards, dilute fertilizer to half-strength and use it once a month in the spring, summer and fall.

Use plant food that is low in nitrogen and high in phosphorus to restrict leaf growth and encourage blooms on a Crown of Thorns plant. 

How To Get Crown Of Thorns To Branch

If your Crown of thorns plant is growing upwards only and lacking branches, let’s find out how to get the crown of thorns to branch.

Cut off the top so that your plant produces branches. Apical dominance can be removed in this way forcing to reallocate the growth hormones that will stimulate a few dormant buds down on the stem to grow.


Or pinch the growing point of your plant with pruning shears if the plant is too spiny or cut the plant back, about 4 inches (10 cm) from its base. This will force your crown of thorns to produce one branch or many.

If your plant produces only one branch, let the new stem grow for at least 6 months, then again cut off the tip. You sometimes need to prune more than once to force some unruly plants to grow multiple branches.

Root the top of the plant when you cut it off again, spray water on the wound to stop its sap from flowing, and plant this rooted cutting along with the mother plant in the same pot.  Do this 2 or 3 times, that will give you a dense cluster of branches that will look good.

Always wear gloves while pruning a crown of thorns as it is a very spiny plant, also its sap irritates the skin and is poisonous if swallowed.


Nikita is a Succulent lover. She really enjoys planting and nourishing them. She loves to share information about various Succulents on this blog to aware people more about these awesome plants.

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