Euphorbia milii is a succulent that is native to Madagascar. It is mainly grown outdoors but can be kept indoors as a houseplant.
It is characterized by its beautiful bracts, thin foliage, and thorns on its stems. It is also known as the “Crown of Thorns” plant.
Euphorbia milii plants need very little care, but occasional watering and fertilization will keep them healthy and flowering.
In this post, we will go over how to care for an Euphorbia milii plant.
Table of Contents
- 1 What is an Euphorbia Milii Plant?
- 2 How to Care for a Euphorbia Milii?
- 3 FAQ
- 4 Conclusion
- 5 Other Euphorbia Plants
- 6 References
What is an Euphorbia Milii Plant?
Euphorbia milii plants (also known as Crown of Thorns plants) are flowering succulent shrubs with bright green leaves.
The ornamental succulent is native to Madagascar and can survive in many tropical regions of the world.
The plant is so beautiful and popular that the Royal Horticultural Society presented it with an Award of Garden Merit in 1993 .
It is considered one of the oldest houseplants in history because it is a very strong plant that can grow in almost any indoor setting.
Euphorbia milii was named after Baron Milius, the Governor of Bourbon Island who introduced the cultivation of the plant.
The plant has a thought-provoking and interesting history, which is why it has so many different names, such as:
- Christ plants
- Christ thorn plant
- Crown of thorns
- Corona de espinas (Latin America)
Within Christian religious lore, the crown, which was made of stems of thorns, that was worn by Jesus Christ during his crucifixion was comprised entirely of Euphorbia milii plant stems; hence, it is the reason why some also call the plant the “Christ Plant.”
The Crown of Thorns, being a tropical plant, thrives in hot summer climates, blooms in droughts, and frowns at frosts.
The plant is grown outdoors in a container and moved indoors during the cold winter. The plant thrives all year round, making it the best ornamental plant for beginner gardeners and busy folks.
Under natural conditions, the growth of the crown of thorns is between 5 and 6 inches in height.
However, when grown in warm climates in the southern US, like Georgia or Florida, it can reach a height of 3 inches outdoors and 2 inches indoors.
Keep in mind that while the crown of thorns blooms throughout the year, it is more prevalent during winter through spring.
When grown indoors, their blooming season is from late winter through fall.
Because Euphorbia milii blooms an abundance of red and pink flowers, some gardeners believe that the more flowers it blooms, the more luck the owner will have.
In some parts of Southeast Asia, like Thailand, there is folklore that states that the number of blossoms on the Crown of Thorns plant will determine the owner’s good luck and fate.
Different Varieties of Crown of Thorns Plants
There are several types and varieties of Euphorbia milii. There continue to be new hybrids being developed by botanists.
Generally speaking, local nurseries and garden centers will only a few kinds, whereas online retailers may have abundantly more varieties – even rare hybrids.
Below are just a few of our favorite varieties of Crown of Thorn plants.
Euphorbia milii “Brush Fire”: This hybrid has thick, shiny leaves that make it really stand out. The bright red flowers that give this plant its name are right above these thick leaves. When the Brush Fire plant is grown outdoors with many bunched together, the blooming of red flowers can look like a bush on fire. You can grow these plants indoors for home decor but does just as well outside.
Euphorbia milii “Creme Supreme”: The Creme Supreme name is due to the creamy white flowers it blooms. Its leaves are much longer than the typical Crown of Thorns and they look like thick, fleshy grass. The plant’s stems are almost entirely covered in spines, which help protect it from plant pests. With this defense system, it is known to be one of the easiest varieties to grow.
Euphorbia milii “Golden Gem”: The Golden Gem name is derived from irregularly shaped yellow spots on the edges of the leaves. They have sharp spines that are up to an inch long! Its flowers can be bright red or an off-shade yellow. They can bloom year-round, but they need bright sunlight in order to do so.
How to Care for a Euphorbia Milii?
Euphorbia milii, commonly known as the crown of thorns, is a popular houseplant due to its attractive spiny foliage.
This succulent plant requires moderate water and light levels and can be propagated from stem cuttings.
It does best in well-draining but dry soil that is rich in organic matter and requires regular fertilization. When it becomes overgrown, repot the plant into a larger container.
We will go into more detail on Crown of Thorns growing care below.
The best soil for Euphorbia milii plants is soil designed specifically for succulent plants. The reason is that soil designed for succulents drains water well and has nutrients that the plant needs to grow.
Euphorbia milii plant roots cannot remain moist for a long period of time because this will lead to root rot or other fungal diseases. Hence, well-draining soil is a must.
You can either make your own succulent soil by mixing general potting mix with soil amendments that drain water, such as perlite or coconut coir.
Temperature and Climate
Euphorbia milii plants thrive in temperatures between 65 and 75 degrees Fahrenheit. 
It can tolerate temperatures down to 50 degrees Fahrenheit during the winter and up to 90 degrees Fahrenheit during the summer.
The Crown of Thorns will thrive in US hardiness zones 9B through 11. If you plan to plant these plants outside of these zones, you should consider growing them indoors.
Crown of Thorns plants loves the direct sun. You should provide them with at least 4 hours of direct sunlight per day.
However, if you want more bloom, you will want to provide your plant with some midday shade.
If you’re growing them indoors, be sure to position them in a bright, sunny location of the home, especially in the south or west area.
On the other hand, when planting Euphorbia milii plants outdoors, you should plant them in a sunny area in the garden.
They look great in a rock garden and add great curb appeal mixed in with other succulents, cacti, and other xeriscape-type plants.
You should water Euphorbia milii plants only when the soil is dry. In other words, use the soak-and-dry method of watering.
The crown of thorns is highly drought-resistant, so it may take a week before you need to water them again. You can test the soil by using your finger and dipping it into the soil.
Once you know the soil is dry, flood your container with water. Then let the water drain out of the bottom of the pot. You do not want the roots to be soaked in water for long.
Since the Crown of Thorns is a succulent plant, the leaves can store water in their leaves.
However, the leaves can only absorb so much before they become overwatered. Overwatering can lead to root rot and leaf drop.
While the Euphorbia milii plants can grow without fertilizer as they are slow growers, it may help to plant to bloom more flowers.
If you decide to add fertilizer, add it about once a month during springtime. There is no need for fertilizer in the winter.
The best type of fertilizer to use is a slow-release fertilizer. The last thing you want to do is to overfertilize it.
Euphorbia milii plants are rarely affected by pests and disease. But if you grow these plants indoors, pests like mealybugs, plant scales, or spider mites can infest them.
All of these pests can cause damage to the plants by sucking sap from the leaves or stems.
They can also cause the leaves to turn yellow or brown, which may even lead to the death of the plant.
Mealybugs are sap-sucking insects that can infest Euphorbia milii. These bugs can cause plants to wither and reduce growth. If mealybugs are present, insecticide treatment is recommended.
Always follow the insecticide’s directions to ensure that it is safe to use on succulent plants.
Ensure that the insecticide is applied to all sections of the plant. Reapply as required until mealybugs are completely eradicated.
Spider mites are another common pest that can be found on Euphorbia milii plants.
These tiny pests can cause extensive damage to the plant by sucking the sap from the leaves. The best way to get rid of spider mites is by using an insecticide.
Alternatively, use rubbing alcohol with a cotton ball to wipe all the leaves, including the undersides of the leaves. Repeat this treatment every seven days or until the spider mites are gone.
Repotting Euphorbia milii plants should be done every two to three years. It is best to repot these plants in late winter to early spring because they will come out of dormancy and enter the growing season.
Make sure you choose potting soil that drains quickly and can accommodate some nutrients for the plant to absorb.
As the potting soil ages, it begins to lose its ability to retain nutrients and hold water effectively. That’s why it’s better to change them periodically.
Lastly, remember to remove the old potting soil carefully without damaging the roots.
You can propagate Euphorbia milii by using its cuttings (either stem or tip cuttings).
First, you should water your plants for a couple of days before pruning your plants to take your stem cuttings to ensure that the cuttings have an adequate supply of water in their stems.
Cut the top 4 to 5 inches of a strong, fresh stem with sterile pruning shears.
You may prefer to cut a larger piece to form the mother plant, but then reduce it to 3–4 inches in length for propagation. Ensure that the stems you cut have some leaves on them.
Spray some cold water on the cut end to halt the flow of sap. The sap is irritating to the skin and can stain clothing and soft furnishings, so wear gloves and shield your eyes.
Place the Christ plant cuttings on a wet paper towel for 3-5 days to allow the wound to callous; this is an absolutely essential step.
It’s not a necessary step, but using a rooting hormone will increase the chances of rooting.
Remove the majority of the leaves from the cuttings, keeping three or four intact. At this time, keep the cuttings out of direct sunlight. Place them in a pot with well-drained soil.
Once the pots are completely filled with the potting mixture, poke a hole about 1 1/2 inches deep with a pencil or your finger.
If you have rooting hormone powder, place a small amount in a small container and dip the cut end into it—enough to coat it but not more.
Ensure that any residual hormone powder is disposed of properly. Fill the hole with the powdery, cut end, then firm the dirt around the cutting carefully. Place the pot in a place that gets a lot of light but isn’t directly in the sun.
After you are finished, water the cut sparingly. After that, water every few days, but simply enough to maintain a medium moisture soil.
Do not water like a regular plant because the baby plant (new plant) does not yet have roots to take water from the soil. Watering as normal will risk causing some rotting in the soil.
It will take several weeks for the stem cutting to establish itself and its roots.
Once you observe new stem growth, transfer the new plant to its own pot with fresh soil and resume a normal watering schedule.
Euphorbia milii needs to be pruned in the spring and summer as it typically grows vigorously during this time of year.
Make sure you use a good pruner to maintain its shape and size. Remove old branches with withered leaves in the fall.
This will help stimulate new growth in preparation for spring. Always wear gloves and clean your pruner after each use.
Does Euphorbia Milii Need Full Sun?
Yes, Euphorbia milii needs full sun. When planted outdoors, Euphorbia milii requires plenty of sunlight and well-drained soil. In particularly hot and dry locations, the plants will require shade to avoid leaf burn during the daytime sun.
How Do You Make Euphorbia Milii Bloom?
To make Euphorbia milii bloom, you need to limit the sunlight. Crown of thorns plants thrives in full sun, which equates to four to six hours of sunlight every day. Any more than that will be too much for these plants. Euphorbia milii will typically bloom at night.
Why Is My Crown of Thorns Not Blooming?
Crown of thorns plants are not blooming because there is a sudden change in temperature or an increase in moisture like rain or overwatering. Euphorbia milii is sensitive to both temperature and moisture. So, the loss of blooming flowers is a good indication that there is sudden cool weather or a rainy stretch. With the proper growing conditions, you may enjoy beautiful blossoms all year. Provide plenty of direct sunlight—at least three or four hours every day.
Why Are the Leaves on My Crown of Thorns Turning Brown?
Leaves on Crown of Thorns plants turn brown because of insufficient water and excessive sun exposure. If you live in a sunny place, Crown of Thorns will thrive. However, too much sun will sunburn and shock the plant.
Are Crown of Thorns Plants Toxic?
Yes, Crown of Thorns plants are poisonous if touched. Do not touch the sharp thorns or get in contact with the milky sap, as it is a skin irritant. Always wear gloves when you want to trim or prune them and keep them away from kids or pets.
The Crown of thorns is a succulent plant that is easy to maintain and does well in direct sun.
If you don’t have much experience with indoor planting or are looking for a simple but bright-colored landscaping plant, then a Crown of Thorns will be a good choice for you.
Other Euphorbia Plants
Euphorbia milii, or Crown of Thorns, makes great landscaping plants. However, there are other types of Euphorbia plants that you can plant. Check out our list of other types of Euphorbia to grow in your indoor or outdoor garden!
Euphorbia Lactea Cristata: More commonly known as the Coral Cactus, it is probably one of the best-looking Euphorbia plants. The plant has fan-shaped branches that grow in a waving pattern that resembles an ocean reef. The stems and branches range from vivid green to blue-gray or even silver in hue. When it is stressed, the edges of the wavy leaves sometimes take on a pinkish tinge.
Euphorbia Hypericifolia Inneuphdia: Most commonly known as the Diamond Frost Euphorbia, it is a very hardy plant that can handle almost everything you throw at it. It is super easy to take care of and its pretty little white flowers don’t need any deadheading. It can be used as a cut flower in flower arrangements or grown on its own adding texture and curb appeal to any front yard.
Euphorbia Leucodendron: Cat Tails Euphorbia Plant is the common name for this plant. Euphorbia leucodendron, a succulent shrub with spineless branches, can develop into a small tree under optimal conditions. It is an excellent landscape plant. It is native to the subtropical region of Madagascar, where it can grow up to more than 10 feet tall. It is not the same plant as Euphorbia tirucalli because its stems are much thinner and have fewer branches.
Lindsey Hyland grew up in Arizona where she studied at the University of Arizona’s Controlled Environment Agriculture Center. She continued her gardening education by working on organic farms in both rural and urban settings. She started UrbanOrganicYield.com to share gardening tips and tactics. She’s happy to talk about succulents and houseplants or vegetables and herbs – or just about anything in a backyard garden or hydroponics garden.