Plants, like fashion, somehow get outdated and will make a come back after some time. Crown-of-thorns is one example of those plants that have been popular in the past, gone old-fashioned but found its way back in the line with its renewed beauty.
As a slow grower and low maintenance plant, a pot of crown-of-thorns surely deserves a spot in your home. It survives unfavorable growing conditions leaving other annuals and perennials behind. With proper care and maintenance, crown-of-thorns can last a long period of time.
| Scientific Name | Euphorbia milii |
| AKA | Crown-of-Thorns, Christ Crown, Rosa (Corona) Espinas |
| Similar to | Impatiens |
| Native to | Madagascar |
| Shape | Elongated leaves with tiny flowers sheathed in colorful bracts |
| Maximum size | 12-14 inches |
| Watering requirements | Low |
| Light requirements | Bright light to full sun |
| Preferred humidity | Low |
| Preferred temperature | 65° F (18° C) or higher |
| Soil or Potting Medium | Well-drained, sandy potting mix |
| Fertilizer | Medium
Use half strength of liquid fertilizer monthly Use high-phosphorus fertilizer when it reached the flowering stage |
| Propagation method | Seeds, grafting, or cuttings |
| Toxicity | Moderately toxic to cats and dogs |
| Vulnerable to | Scale, mealy bugs, and occasionally aphids |
Crown of Thorns Houseplant Overview
A native of Madagascar, crown-of-thorns (Euphorbia milii) is an ornamental plant that’s a succulent in nature. It’s a member of the Euphorbiaceae (Spurge) family. A popular legend says that crown-of-thorns was the plant used on Christ’s head during the crucifixion, thus its common name.
The stem of crown-of-thorns is woody and thorny and it functions as an efficient water reservoir. The leaves take the form of an oblong and the flowers appear in clusters as tiny yellow sheltered by bean-shaped bracts of red color. The new varieties of crown-of-thorns have red, orange, salmon pink, white, and even bi-color bracts making it more appealing to the eyes.
Water Requirement
Crown-of-thorns have a low water requirement and it’s perfectly fine if you leave it there for weeks without water. Make sure to let the soil dry out completely in between waterings. It has enough water supply in its stem so there’s no need to worry.
Most folks make the mistake of overwatering this plant. If do so by accident, you’ll be noticing the stems getting rotten. That’s a sign the roots below have suffered already and you have to seriously rescue your crown-of-thorns.
Light Requirement
A sucker for light, that’s one major characteristic of this indoor ornamental. Crown-of-thorns do love bright light to full sun. Make sure to reserve the brightest spot in your home for this plant.
If the light is lacking, you can bring your potted crown-of-thorns outside for sunbathing. Full sun is a requirement to trigger blooming. When the light level is low like during the winter seasons, you can supplement light using artificial sources.
Humidity & Temperature Preferences
Low humidity and high temperatures are favorable for your crown-of-thorns. These extreme conditions that usually make tropical plants struggle won’t affect your plant. It’s their nature to thrive in those conditions.
You can keep your potted crown-of-thorns in a dry place together with other succulents and cactus if you have one. A temperature of 65° F (18° C) or higher is preferred. Low temperatures can inhibit flowering and induce leaf dropping which are signs that the lant is going dormant.
Plant Food and Potting Media
Use a well-drained potting mix amended with sand. Do not make lightweight mixes because crown-of-thorns can grow top-heavy. To support the heavy structure atop, the soil below must be stable enough.
Add fertilizer at planting using either a solution containing 150-275 ppm fertilizer or a medium rate of slow-release fertilizer. After that, you can fertilize the crown-of-thorns monthly using half the strength of the liquid fertilizer. This shall serve as their regular feeding.
To encourage flowering, apply a fertilizer that’s higher in phosphorus content when it reached the flowering stage. Do not commit the mistake of overfertilizing your plant. We do not want our plants suffering from leaf tip burning with excess salts building up in the soil.
Additional Care
Pruning
Like most plants, crown-of-thorns benefit from occasional pruning. From time to time, you’ll need to remove aged leaves and stems and dispose them for good. You can do this during autumn so that when spring starts, new growths will start showing.
Braches that are leaning towards an undesired direction can be trimmed as well. The idea is to keep the plant in shape. If you think that the apical portion of your plant is getting heavy, you can cut back a few stems to keep it light.
Be extra cautious in pruning crown-of-thorns. The white, milky sap that bleeds out of the cut are irritating to the skin and eyes. Always sterilize your pruning shears or scissors to avoid spreading diseases from plant to plant.
Repotting
Your potted crown-of-thorns will surely need repotting once every two years. Remember that this houseplant is a slow grower so it’ll take a little more time before you shift it to a larger pot. If you’re consistent with pruning extra stems and waters the plant only when needed, the probability of repotting at a sooner time is low.
When the crown-of-thorns is mature enough and has outgrown its present container, you must repot the plant to keep it healthy. The best time to do it is during summer because this time, crown-of-thorns is at its hardiest. Choosing the right time for repotting will lessen the stress that the plant has to undergo.
- Carefully remove the crown-of-thorns from its current pots. Loosen the soil and trim off aged and dead roots. On top, you may also remove other stems or branches to keep it lighter.
- Prepare a well-draining potting mix with sand and put an inch thick in the pot. Settle the plant there a little lower than its original placement and fill the spaces with the remaining mix.
- Water the newly repotted crown and let the excess water drain out completely.
- Bring the pot in a location that has at least 4 hours of sunlight and let it sit there.
Propagation
The best and easiest way to propagate your crown-of-thorns is by stem cuttings. All you need is to cut a mature, good-quality stem from its mother plant. Plant it separately in a pot and wait until it develops its own roots.
Newly propagated cuttings should be placed in a location that’s warm and has no direct light. Unlike in other plants, there’s no need to water the pot to avoid root rot. Just wait until new growths appear and then you can start giving water.
It usually takes a month of waiting before that stem cuttings get fully established as an individual plant. Don’t worry because they have a high chance of survival. You’ll definitely have those babies growing in time.
Pests & Diseases
Scale and mealybugs are the usual pests of crown-of-thorns. Sometimes, they can get infected by aphids too. Infestation is not much of a problem though since this plant is a tough one.
Just be observant and always look for the presence of these harmful organisms. You can remove them manually if they’re just a few. Apply water spray with enough pressure to scrape them off the leaves or stems.
Other solutions include using diluted insecticidal soap or dishwashing liquid or swabbing with cotton dabbed in alcohol. You may also opt to just remove the infected part.
Toxicity
The milky sap of the crown-of-thorns is the culprit for its toxicity. It’s considered mildly toxic to cats and dogs. If ingested, they can irritate the mouth, gastrointestinal tract, skin, and eyes.
Even for humans, contact with the sap can also lead to irritation. It’s wise to always handle it with extra caution. Aside from the sap, the thorns also sting.
Typical Questions for Crown of Thorns Growing
How do I increase the flowers of my crown-of-thorns?
To achieve lush clusters of flowers, you have to provide an ample amount of light to your crown-of-thorns. If pots are kept in a relatively darker room, it will find trouble producing flowers. You have to relocate the plant somewhere well-lit.
Another factor is the lack of nutrients that will initiate flower formation such as phosphorus. Remember to apply fertilizer with higher phosphorus content once it reaches the flowering stage.
Why are my crown-of-thorn leaves turning yellow?
The most probable reason for yellowing leaves is overwatering. Crown-of-thorns doesn’t like so much water because they’re succulents. They have enough water to supply their needs.
Overwatering leads to root rot. When roots start to rot, their function will be compromised making water and nutrients unavailable for the entire plant. Thus, leaves will show signs of dying turning from green to yellow.
If intervention isn’t done immediately, your crown is in danger of early death. You have to stop adding water to the plant until it recovers from the stress brought by overwatering. Place the pot under full sun to facilitate faster evapotranspiration.
Is the crown-of-thorns toxic to pets?
They are considered mildly toxic to cats and dogs. The milky sap that bleeds out of the cut portions is responsible for its toxic properties. When touched, it causes irritation to the skin.
If ingested, your pets will show signs of irritation to the mouth and GI tract. Always consult your veterinarian when this happens to provide immediate treatment.
Conclusion
Though once forgotten, crown-of-thorns has regained its spot in the landscape. It only proves that this ornamental plant is classical. With research and technology advancement, we can expect more varieties and hybrids to appear in the coming years.
Without demanding rigorous care and maintenance, crown-of-thorns surely fit the schedule of busy plant owners. And the fact that it can withstand drastically poor conditions is a big advantage for those who struggle with raising indoor plants.
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