How to Grow Crown of Thorns – A Quick Guide!

When we think about succulents, we mostly picture plants with fleshy, green leaves and little to no flowers. However, not all succulents look like that. There are various kinds in this huge plant family that are very different from one another.

Crown of thorns is one of the more unique succulents that can add a splash of color to your surroundings with their radiant flower clusters and bright green foliage. Here’s what you need to know about growing and caring for these plants. 

About Crown of Thorns

how to grow crown of thorns

Botanically named “Euphorbia milii”, these plants are also known as “Christ plants” or “Christ thorn”. Originally indigenous to Madagascar, they began to spread gradually across the world after the 19th century, starting from France. Though Crown of thorns is mainly grown as an indoor houseplant, they’re naturalized in many regions around the world in both indoor and outdoor environments. 

Christ plants (Crown of thorns) are known for their sharp, pointy prickles, bright green leaves, and small flowers that come in numerous colors including red, pink, white, yellow, and even bi-colors. 

They’re best grown in USDA zones 9 to 11 while in colder climates they can only be grown inside.

How to Propagate and Plant Crown of Thorns

white crown of thorns

Crown of thorns can be grown from both seeds and cuttings, but seed propagation is much more complicated and takes time, so the most convenient method would be using cuttings. Here’s how to do it:  

1. Take the Cuttings

The best time to take cuttings from Christ plants is in the spring or summer when the new growing season has started. Don’t forget to take some extra cuttings as there’s a chance that some of them won’t root successfully.

  • First, choose some of the healthy plants and water them well for at least 1 or 2 days before taking the cuttings. This will give the plants enough time to store water in their stems.
  • Next, prepare a sharp, clean knife or a pruner and a thick pair of gardening or leather gloves as tools to protect your hands from the thorns.
  • Choose young, fresh stems and cut the top parts off, making sure that each one is about 3 to 4 inches long. There should be some leaves on them as well. 
  • These plants release a milky sap that can be harmful to human eyes and skin, so to be safe, spray the cut ends with some cool water as it will stop the sap from flowing.

2. Prepare the Cuttings

Now that you have your cuttings, remove any leaves from the bottom part, leaving only a couple on the top part. Then, place the cuttings on some clean paper towels and store them in a cool, dry place. 

This is an important step in the propagation process since it’s necessary to dry them properly before the planting is done. Planting cuttings as soon as you take them can cause root rot due to wetness on their cut ends. 

It can take a couple of days for a cutting to dry out properly and this time period depends on the temperature and humidity of the specific environment they’re kept in. When the cutting ends look shriveled and have turned greyish, this means that they have dried up properly and are ready to be planted.

3. Prepare the Potting Mix

getting potting mix ready

Crown of thorns prefers well-draining, neutral or acidic, sandy soil with a pH level below 7.0. Higher pH levels aren’t ideal for these plants, so if your soil pH is too high, you can always lower it by adding agricultural sulphur to the soil. 

However, Christ plants don’t do well when planted in soil alone. This is why you will need to prepare a moist growing media by mixing other materials into the soil such as bark, peat moss, and perlite. For example, a potting mix made with equal parts of soil and the above-said materials makes a great growing media for these plants.

4. Planting the Cuttings

Plant the cuttings in small pots that are about 3 inches in diameter. This size is enough since you will need to transplant them anyway in bigger pots later on. 

  • First, fill the pots with pre-prepared potting mix.
  • Coat the planting ends of the cuttings with some hormone powder for faster and better rooting.
  • Use a pencil to make holes in the potting mix about 1 ½ inches deep.
  • Coat the ends of the cuttings in hormone powder and place them in these holes, pressing down the soil firmly using your hands.
  • Water well to make the soil moist, but not too damp.
  • Keep them in a bright and sunny place or under grow lights.

5. Re-planting the Young Plants

Cuttings normally root within 3-4 weeks, but they can also take more time. Keep a close eye on the roots. Once they have grown about 1-2 inches long, they’re ready to be re-planted. 

Choose containers about 6-8 inches in size with enough drainage holes to transplant your young crown of thorns. Use pots made from porous materials such as terracotta as such containers will help in maintaining better water drainage.

6. Where to Place Your Plants

succulents on a window sill

Crown of thorns needs at least 3-4 hours of full sun per day to flourish. While the ideal temperature should be maintained between 65-75 degrees Fahrenheit (18-23 Celsius), these plants can tolerate temperatures much higher than that as well.

Place your plants on a sunny windowsill or somewhere where they will be exposed to sunlight for healthy growth and a better flowering experience. However, they won’t survive in temperatures below 54 Fahrenheit degrees (12 Celsius) so you’ll need to keep this in mind during the winter. 

How to Maintain Your Crown of Thorns 

watering plants

Watering

Like all succulents, these plants are drought-tolerant and only need to be watered when the soil is completely dry and hard. When watering, make sure to do it thoroughly until the water drains out from the bottom drainage holes.

Fertilizing

Crown of thorns aren’t heavy feeding plants so they can survive even without any additional nourishment at all. However, you can always give them a little bit of fertilizer now and then to boost their growth.  

Fertilize your plants with a slow-releasing and well-balanced diluted fertilizer in the spring and summer. You can also use granulated fertilizer, about 4 tablespoons for every 10 square feet.

Pest and Disease Control

mealy bugs on a plant
Mealy bugs

While mealybugs often infest Crown of thorns plants, some other common garden pests include spider mites, thrips, whiteflies, and scales. Wash off the pests with water and spray the plants with a pesticide to treat the infestations.

Most of the time over-watering is the main cause of diseases and fungal infections that affect these plants. Root and stem rot and discolored and curled leaves are just a couple of examples of such cases. If infected, separate the sick plants from the good ones immediately and then use a fungicide or horticultural oil to control the spreading and prevent a relapse.

Re-Potting

Crown of thorns are slow-growers so re-potting them once every 2 years is sufficient. Do this in the summer as these plants get extra hardy and strong within that time period. It helps with lessening the stress on the plants caused by moving and adjusting to their new homes. 

Always choose pots that are only 1-2 inches bigger than the previous ones as these plants like to be grown in a somewhat tight space. First, loosen the soil and take out the plants carefully without harming the root ball and remove any dried up or damaged root parts. Then, plant them in the new pots that are filled with fresh growing media and water well.

Pruning

Occasional pruning is a must for crown of thorns to keep them in shape and good health. Autumn is the best time to prune them as this will stimulate new growth by the start of the spring. 

Trim any excessively long branches and ones that have grown in unwanted directions. Remove all the dried-up and damaged leaves, stems, and also flowers to complete the pruning. When doing so, don’t forget to take all the necessary safety precautions to protect your eyes and skin from the poisonous sap and sharp thorns of these plants.

The Take-Away

Crown of thorns is an extremely easy houseplant to grow and maintain as it doesn’t much effort or gardening know-how. If you’re looking for a plant that won’t take up much of your precious time these plants are an excellent choice! 

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