Crown of Thorns Plant Leaves Turning Yellow – Reasons Why?

Euphorbia milii, the Crown of Thorns plant, is a popular decorative succulent from Madagascar. 

The crown of thorns grows as a landscape plant or potted for use indoors and out.

Leaves of Crown of Thorns turning yellowPin
Crown of Thorns blooms with yellow leaves in background | PlantCareToday

You may also know this plant from other common names, including:

  • Christ Thorn
  • Christ Plant
  • Euphorbia milii 

Euphorbia milii displays:

  • Graceful, thorny stalks
  • Bright green leaves
  • Vibrant flowers that bloom even in winter

The crown of thorns plant needs proper care if it looks its best year-round. However, you may suddenly notice its leaves turning yellow.

But with the right environment, you can prevent your crown of thorns and plant leaves from turning yellow.

Related: Details on Crown of Thorns Plant Care

In this article, we’ll delve into why your Crown of Thorns plant leaves are turning yellow and how to control it.

Yellowing Crown of Thorns – Is That Normal?

Given proper care, a crown of thorns plant has emerald green leaves and white, pink, red, and even yellow flowers. 

Though usually considered a small succulent, a healthy crown of thorns typically grows up to two to three feet tall.

Like most succulents, the crown of thorns plant can begin to lose its bold colors without proper care. If anything in their environment is off, leaves start to turn yellow and drop off faster than usual.

Yellowing Crown of Thorns, small potPin

Yellowing can be due to many different environmental factors. Often, succulent plant leaves shrivel and turn yellow due to lack of water. But other stress factors can also cause yellow leaves, from rapid temperature changes and lack of nutrients to poor soil quality.

Too much light will result in yellowing leaves.

What Does Yellowing Crown of Thorns Leaves Indicate?

There are a couple of reasons why your crown of thorns might be starting to yellow. First, many gardeners immediately assume it’s due to underwatering.

Underwatering is usually accompanied by telltale shriveling and wilting.

With succulents like the Crown of Thorns, overwatering tends to be more of an issue for plant health. It can result in the absence of new growth, leaf loss, or leaves yellowing or turning brown and crisping up. 

Moreover, overwatering can cause root rot, spongy or stem rot, and make the plant prone to diseases and pests like aphids, thrips, scales, mealybugs, and spider mites.

As a desert plant, the crown of thorns doesn’t need very much water to survive. However, too much can cause damage to the leaves on a cellular level.

Peach-colored Euphorbia flowers with green leaves.Pin
Photo Credit: Instagram @succulentsmylovely

You should stick to watering your crown of thorns roughly once per week. Allow the soil to dry between waterings. Then, you can water more or less as needed, depending on factors such as the size and location of your plant.

Sunlight is another important consideration with the crown of thorns. Like most succulents, they do best in full sun that mimics their natural environment. They will also do well in bright, direct sunlight.

Crown of thorns plants also prefers higher temperatures, about 65° to 90° degrees Fahrenheit. Move them if possible or shelter them when frost begins to hit. Otherwise, leaves may start to yellow, and the houseplant can eventually die.

Regarding humidity levels, cold temperatures, and high humidity can also contribute to the Crown of Thorns plant leaves turning yellow.

Sometimes, you may see your crown of thorns plant leaves turning yellow simply because they’re not getting the nutrients they need. A high-phosphorus environment can help mature plants thrive in your garden.

How To Control Crown of Thorns Plant Leaves Turning Yellow

A proper care schedule can prevent the leaves of your crown of thorns from turning yellow. It’s important to water and fertilize regularly. 

If you live in a four-season area, you will want to move your plant depending on the time of year.

Close-up of pink-tinged euphorbia flowers.Pin
Photo Credit: Instagram @hnoiphoodoi_photography

Question: Is Crown of Thorns Poisonous?

There are a couple of things that you can do to keep your crown of thorns from turning yellow:

  • A regular watering schedule is vital to good plant health. For most gardeners, watering weekly will suffice. But remember to restrict watering when it begins to get cold.
  • When container-grown, ensure the pot has adequate drainage holes to allow the excess water to drain freely. This will also prevent the plant from sitting in excess water.
  • Provide full sun exposure but not for a whole day, and provide some necessary shade.
  • Avoid adding fertilizer during winter, and prepare your plant for next year’s bloom.
  • Using the right potting mix helps ensure that your crown of thorns never ends up overwatered. Provide plenty of drainage for the root system. The plant will only take the water it needs to survive.
  • Adding pumice to your soil is a good way to provide drainage for succulents such as the crown of thorns.
  • You can also add components such as sand or perlite to your soil to help break it up.
  • Some gardeners like to add peat moss for both texture and nutrition.
  • Add liquid fertilizer or cactus-labeled feed if your plant is not getting the nutrients it needs from the soil. It’s best to fertilize when first planting using a slow-release fertilizer. Afterward, apply half-strength fertilizer or nitrogen-rich fertilizer as needed until your plant is back to its bright, vibrant self.
  • Prune damaged or yellowing leaves to prevent further spread of disease.

If you give your crown of thorns plant proper care, it can thrive for years. Prevent yellowing by giving your plant the right level of moisture, sunlight, and nutrients.

This allows this desert succulent to thrive.

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