crown of thorns

How To Grow and Care for Crown Of Thorns Plants (Euphorbia milii)

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Are you looking for an easy to propagate, easy maintenance, colorful plant to add to your garden? If so, it’s time to consider learning how to grow the Crown of Thorns, or Euphorbia milii.

This species grows and flowers more often in the summer or spring, but still thrives year-round. All year, you will have vibrant and healthy houseplants for your garden or home. 

Originally from Madagascar, this species has had a rich history of naturally crossing with other plants to produce unique succulent-like shrubs. For example, instead of only producing bright yellow or red flowers, certain varieties and cultivars produce light pink, white, or cream colors that can change throughout the season. 

In this article, we’ve compiled a guide to all you need to know about Crown of Thorns.

Plant Facts:

Scientific nameEuphorbia milii
Common namesChrist plant, Christ thorn 
FamilyEuphorbiaceae
Plant TypeOutdoor or houseplant, spurges
Height and Width5–6 ft. tall (in the country of origin), 2-3 fit. Tall (houseplant), 1–3 ft. wide (indoors), 1 ft. 6 in. – 3 ft. in width
OriginMadagascar
Flower colorsGreen flowers inclosed with bracts of red or yellow, pastel colors (depending on cultivar)
Foliage colorBright green 
Sun ExposureIndirect sun (indoors), full sun (outdoors), partial shade (if living in extremely hot climates)
Soil Type & pHDry-medium moisture, well-draining soils, acidic, alkaline, or neutral (5.0-7.0)
Special featuresFlowers bloom throughout the year, leaves drop in a cyclical pattern (around winter), has long spines that may be dangerous for pets, prefers low humidity, poisonous to humans and animals (skin irritation, nausea, vomiting, diarrhea)

How to Grow Crown of Thorns 

If you’re looking for a versatile plant, Crown of Thorns might be a nice addition to your collection. You can grow this species in your garden bed, as a border specimen, as a hedge, or in a container. 

Additionally, you can keep them indoors or outdoors. Either way, you just need to make sure that they get through sunlight. 

E. milii can also grow year-round. In other words, you can plant them whenever you want. Their preferred season is Spring, but they still grow well in the other seasons too. If you are planning to grow it during the hot summer, make sure E. milii receives partial shade around noontime. 

Without further ado, let’s look at how to grow this hardy plant.

Propagation

The best time for cuttings is during the spring and summer months when it is actively thriving. You can also propagate this plant from seeds, but taking cuttings is more efficient. We will explore both options in the sections below.

Propagating from Cuttings:

Before cutting for propagation, take note that the sap that comes out of E. miliis stems and leaves are extremely sticky and toxic if ingested. It is important to wear gloves and avoid touching your eyes and mouth when cutting the stems or leaves. 

Take a 3-4 inch long cutting. Lay the cuttings on a newspaper in a cool, dry place. This will promote root growth. This process usually takes a couple of days until the cut ends of the leaves callus (harden).

Once the cuttings have dried and callused, you can now start propagating them. 

It is recommended to propagate from cuttings rather than seeds as the process takes less time, requires less management, and has a higher chance of taking root. The soil for the cuttings must be equal parts moist peat and sand. The soil must allow for proper ventilation and be well-draining. 

Prepare a 4-5 in. wide pot and grab some of the callused cuttings you set aside. Then, gently push the callused into the soil so about half the cutting is sticking out of the soil. Keep the soil lightly moist and set the container in an area that gets plenty of indirect sun. Propagation usually takes 3-4 months, so be patient and enjoy watching E. milii grow. 

Propagating from Seeds:

Seeds must be sown immediately. Sow seeds then lightly cover with soil. Keep the soil moist while covering the seeds with a clear, plastic lid. It is recommended that you place a heating pad underneath the pot, but it is not absolutely necessary. Placing the heating pad under your container will contribute greatly to the health and growth of the plant, but if you do not have a heating pad, keeping your seeds in a brightly lit area will do fine. 

Make sure to keep the seeds in a place where plenty of light pours over it. Once you begin to see the little baby plants sprouting up, you can remove the clear plastic lid and keep the surface moist. You can transplant when leaves have sprouted.

Soil

These succulents are extremely low maintenance when it comes to soil care. They need well-draining, acidic-neutral soil.

Organic soil works best, so if you want to concoct your own soil mixture, feel free to do so! Make sure that your soil is equal parts peat, compost, or organic manure mixed with sand, chalk, or loam. Gravel is discouraged because it provides too rough of a texture for most plants. In other words, mixing with gravel might affect the roots. 

In terms of the moisture level of the soil, it is important to let the soil dry in between waterings to prevent waterlogging of the plant or root rot. 

Pruning

Luckily, E. milii is easy to prune! You can prune the plant into any size, shape, or height you desire. Keep in mind that both the stems and the leaves have an extremely sticky sap-like goo that seeps out when cut. In addition, this plant does have spikes and thorns, so please be mindful of those when you handle this plant (especially when pruning!). 

After you’ve inspected, cleaned, and sharpened your tool of choice, make sure to cut the stem at its place of origin. In other words, cut as far back from where it originally started growing as you can. This will prevent the uneven growing of all your stems altogether. 

Properly dispose of your cut stems and watch as your freshly-pruned Crown of Thorns plant comes back fuller!

Repotting & Transplanting 

To repot or transplant a E. milii plant that has grown too large, gently wrap a gloved hand around the base and use your other hand to loosen some of the soil around the plant. Then, you can carefully pull the plant out. 

After the plant is free from the pot, gently shake off the excess soil from the leaves and use your fingers to clean the roots of the old soil. When you place the plant in its new home, plant it an inch or two lower than it sat in the old pot. After that, fill the excess room around the root ball with soil. Fill with soil and pat down firmly. 

crown of thorns

How to Care for Crown of Thorns

Because E. milii is relatively low-maintenance, caring for it is quite easy. Let’s take a look at what this plant needs to thrive in your home or garden.

Water

Crown of thorns cactus does not need regular watering to survive. In fact, if you overwater the plant, it can cause root rot, wilty leaves and flowers, and yellowing of the foliage. 

It is recommended to water E. milii when the soil has dried out. Usually, it takes 2-3 weeks for the soil to completely dry. After that period of time, you can water. That being said, this plant rarely needs any water during the winter months. Excessive watering during the colder months can potentially be fatal to this plant. 

In all, simply keep an eye on the soil. If it is dried out, you can then water it. 

Sunlight

These plants thrive off of sunlight. They are no stranger to bright, sunny days. If you house them indoors, make sure that they are by a bright, sunny window that receives sunlight for the majority of the day. Similar lighting is required for patios. 

If you do not have a window that gets plenty of sun throughout the day, you can pair the indirect light with artificial lighting. Although, it is best to keep them in natural sunlight if possible. For outside growing, this plant does well with all-day sun. Keep E. milii partially shaded at midday during the hot summer months. 

Temperature & Humidity

Crown of Thorns can tolerate just about any temperature, but they truly thrive in moderate temperatures (55-80 degrees Fahrenheit). Unless you live in an area that consistently dips below 35 degrees Fahrenheit, these plants can grow under almost any temperature. 

These plants like low levels of humidity. If you are keeping this plant indoors, it might be a good idea to lightly spritz it with a spray bottle, although this isn’t necessary unless conditions are extremely dry.

Fertilizer

Over-fertilizing can negatively affect the health of E. milii. When you over-fertilize, the flowers and leaves can become soft. When you do fertilize, it should be with one that is well-balanced 

You can fertilize during the spring and summer months. Avoid fertilizers with high levels of micronutrients as the plant reacts negatively to minerals such as Boron.

Pests & Diseases

Although E. milii is relatively resistant to pests and diseases, there are still a few to watch out for.

Leaf Spots

Leaf spots are small, discolored spots that appear on some of the leaves on your plants. The spots are usually brown or yellow in color and are usually caused by a fungus or bacterial infection.

Root Rot

Root rot is hard to spot since it occurs beneath the soil. However, it can still be identified by carefully looking at the roots of your plant. The roots, when infected, usually turn a brown color and grow soft. This disease is usually caused by overwatering.

Botrytis Blight

Botrytis blight is a grey-colored fungus that can appear on a plant’s flowers, buds, or leaves. When a plant is infected, its flowers usually turn brown and rot quickly. This disease usually occurs due to a fungal or bacterial infection.

Mealybugs

Mealybugs are small, white-colored bugs that are hard to spot on your plants. They usually arrive due to excessive moisture within or around the plant. Similar to mealybugs are scale, mites, and thrips that can severely damage the foliage of your plant and, if left untreated, could kill your plant.

Common Varieties & Cultivars

There are several different varieties of Crown of Thorns that offer different colored flowers. For example, growers in Germany naturally crossed this plant to create varieties such as the Samona and Gabriella. 

In addition to these two varieties, there is also Rosalie, Volcanus, and Saturnus. All of these varieties are a form of California-hybrid with leaves that are greener and bushier, along with more vibrant flower colors. 

Because of the demand for the vibrant colors this plant offers, there are highly-desirable cultivars being grown and developed all over the place (especially in Thailand). Short-and-Sweet and Mini-Bell were different cultivars that were grown to be compact and “dwarf-sized.” 

There are also cultivars with pastel shades that contrast the vibrant colors of the traditional red or yellow:

  • “Jingle Bells” has a soft pink color with red or green tinges.
  • “New Year” has yellow bracts that shift to red as they grow older.
  • “Pink Christmas” has pink flowers with complimentary red streaks. 

Conclusion

If you are looking for a low-maintenance, flowering plant for your collection, Crown of Thorns may be right for you. You can plant them as hedges, border plants, shrubs, potted plants, or a statement piece for your garden. Depending on the variety or cultivar you desire, the flowers offer a nice pop of color to any home or garden. 

E. milii can thrive almost anywhere. If you live in a heavily wintered area, you can still maintain it as a houseplant. Chat with your local nursery for more information about where to buy it!

*image by Wirestock/depositphotos

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