Crown of Thorns (Euphorbia milii) is a tropical plant, so it is impossible to grow it outdoors year-round unless you live in USDA hardiness zones 9 through 11.
However, if you are fortunate enough to live in one of these tropical, semi-tropical, or desert settings, you can grow this attractive plant outdoors year-round.
In other settings, your Crown of Thorns can spend the summertime outside but must come in and live as a houseplant during the winter months. In this article, we share details on keeping Crown of Thorns as an outdoor plant.
What Is The Crown of Thorns Plant?
Crown of Thorns is a tropical, succulent perennial hailing from Madagascar. The plant is extremely tolerant of drought and heat and does very well in dry, sharply draining soil. It is an excellent outdoor plant choice in hot, dry, desert settings.
You may hear this plant referred to as:
- Crown of Thorns Euphorbia
- Christ Thorn
- Christ Plant
It is so-called because it is thought that this plant was used to fashion Jesus’ thorny crown at the time of His crucifixion.
The plant’s botanical name is Euphorbia milii (yoo-FOR-bee-uh MIL-ee-eye), and it is related to other types of Euphorbia, such as poinsettia. However, it differs from this type of plant because of its thick, fleshy, tear-shaped succulent leaves.
There are several different selections of this intriguing plant. It’s available in variegated and solid-colored varieties sporting many different colorful bracts and color combinations of pretty flowers.
In tropical and desert settings, Euphorbia milii grows happily as a small shrub or specimen plant in the landscape. With plenty of sun, a warm climate, and sharply draining soil, the plant will bloom profusely throughout the year.
How Do You Keep Outdoor Crown of Thorns in the Landscape?
Location is one of your first considerations when thinking of planting Crown of Thorns in your landscape. This thorny succulent plant has earned its common name, so you’ll want to be sure to choose a location for it that is well away from the beaten path.
It should also have plenty of surrounding space so that you do not encounter its painful thorns accidentally when you are attending to other plants.
Bright Light and Sharply Draining Soil are Essential
In addition to choosing a setting that takes your safety into account, you should also consider the plants’ needs for bright, direct sunlight and sharp well-draining soil.
Without ample, bright sunlight, your plant will not produce as many flowers as you would probably like. Additionally, you must remember that these plants are extremely drought tolerant, so too much water around the root ball will lead to fatal root rot.
To be sure that your Euphorbia milii are well established:
- Keep the soil well irrigated for a couple of weeks after transplanting.
- Keep the potting mix moist for the first couple of weeks.
- Never allow this plant to stand in water for any significant time.
- When you see new growth, reduce watering.
Euphorbia milii are slow growers, but they need to be pruned annually, just before the growing season. To tidy your plants up, trim away any damaged, diseased, or dead stems. Now is an excellent time to start new plants from cuttings.
Propagating this hardy plant is very easy. Kept in a sharp well drained soil and a warm area receiving bright, indirect sunlight, tip cuttings will put down roots eagerly and will soon grow into mature plants.
When handling your Crown of Thorns, be sure to wear protective gloves that will protect you both against the sharp thorns and the irritating latex sap.
Guard Crown of Thorns Against Cold Temperatures
This plant is quite happy in dry, hot settings with temperatures higher than 90° degrees Fahrenheit. Once established, this hardy succulent does very well with little or no maintenance.
As a result, it is an excellent xeriscaping choice in dry, warm climates. Because it is also quite tolerant of salt spray, it’s a good choice for an ocean-side landscape.
Although this is a very rugged plant, understand that it is not at all tolerant of frost. If you live in an area with occasional temperature dips, keep a close eye on the weather forecast. Anytime the forecast predicts temperatures to drop below 45° degrees Fahrenheit, cover your plants.
If temperatures lower than 32° degrees Fahrenheit are anticipated, it’s a good idea to plant these warm weather succulents in containers that can be brought indoors during cold snaps.