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Guide to Growing the Beautiful Crown of Thorns Plant

Learn how to grow and care for the unique, vibrant Beautiful Crown of Thorns Plant (Euphorbia milii) with this step-by-step guide covering everything from planting to blooming.

How to Grow and Care for Crown of Thorns (Euphorbia milii)

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If you’re looking for a bold, eye-catching houseplant, the crown of thorns or Christ plant (Euphorbia milii) may be just what you need. With its thick, winding stems covered in sharp spines and pops of bright flowers, it certainly makes a statement in any space.

Despite its prickly appearance, the crown of thorns is a relatively easy plant to grow indoors. It thrives on neglect and doesn’t require much watering or pruning to maintain its unique form. Just provide it with enough light and well-drained soil, and this durable succulent will reward you with loads of vibrant blooms year after year.

This guide covers everything you need to know to successfully grow crown of thorns as a houseplant, including ideal growing conditions, care requirements, potential issues, and more. With a few tips, you can enjoy this unique plant’s stunning displays for a long time.

What is Crown of Thorns?

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The crown of thorns gets its common name from the sharp, prickly spines that cover its succulent stems and branches. These inch-long spines are actually bharved leaves, not thorns, that have evolved to conserve water in the plant’s native habitat.

Euphorbia milii is a succulent shrub that belongs to the Euphorbiaceae family, which also includes poinsettias and castor beans. It originates from Madagascar but has naturalized in many warm parts of the world.

In its natural environment, the crown of thorns grows into a dense, sprawling shrub up to 6 feet tall. But when grown in containers indoors, it remains a much smaller 1-2 foot plant.

One of the biggest draws of growing crown of thorns is its unique growth habit. The stems are thick and winding, created visually striking forms and shapes. Each stem segment is covered in the plant’s iconic spines and pops of small but vibrantly colored flowers.

Crown of thorns blooms are small, but they pack a punch with their bright reds, yellows, or bicolored patterns. And this plant is amazingly floriferous, capable of producing blooms nearly year-round in the right conditions.

Why Grow Crown of Thorns?

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Euphorbia milii has a number of characteristics that make it an appealing and unique houseplant:

  • Distinctive, sculptural growth habit with winding, branching stems
  • Eye-catching spines that create striking visual texture
  • Amazing bloom displays with small but vibrantly colorful flowers
  • Year-round flowers in the right conditions
  • Very low-maintenance, drought-tolerant succulent
  • No serious pest or disease issues
  • Long-lived (can thrive for over 100 years!)

Although it looks intimidating with its spiny stems, the crown of thorns plant is actually quite easy to grow indoors. Like other succulents, it requires excellent drainage and dry conditions but minimalwatering once established. Proper light and temperatures will keep it blooming nearly continually.

With a naturally small, compact mature size and no major care demands, it makes an excellent conservatory, sunroom or bright window plant. Just be sure to handle it carefully to avoid its sharp spines!

Planting Crown of Thorns

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Fortunately, starting crown of thorns plants indoors is very easy, whether growing from cuttings or nursery transplants.

Growing From Cuttings Many gardeners propagate new crown of thorns plants from stem cuttings of an established plant. This ensures you’ll get the same flower color and growth habit. Here’s how:

  1. Using very sharp, sterilized pruners, take 4-6 inch cuttings from an existing euphorbia milii plant, cutting just below a stem node.
  2. Allow the cuttings to callous over for 1-2 days before continuing.
  3. Fill a small container with a fast-draining cactus/succulent potting mix.
  4. Push the cuttings into the potting mix, ensuring at least 2 nodes are buried under the soil. Space cuttings 3-4 inches apart if planting multiples.
  5. Water the potting mix thoroughly and place in a bright, warm location out of direct sun.
  6. Keep the soil lightly moist and provide bottom heat if possible to encourage rooting.
  7. Once new growth appears in 4-6 weeks, the cuttings have rooted successfully. Allow soil to dry slightly before watering again.

Growing from Nursery Plants You can also purchase small crown of thorns transplants from a garden center or nursery to get a head start.

  1. Select a young, compact plant with plenty of branching but no signs of damage, disease or pests.
  2. Transplant into a container only 1-2″ wider than the nursery pot, using a well-drained potting mix made for cacti and succulents.
  3. Water thoroughly after transplanting and place in a bright spot out of direct sunlight for 2 weeks to recover.
  4. Once established, follow proper crown of thorns care as described below.

The Best Potting Mix Providing excellent drainage is essential for preventing root rot in this succulent plant. Use a quality cactus/succulent mix, or make your own by combining:

  • 2 parts potting soil
  • 1 part coarse sand or perlite
  • 1 part small pebbles or baked clay

Adding a handful of charcoal or bark to the mix can also improve drainage and aeration. Ensure the container has ample drainage holes as well.

Light Requirements

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Very few houseplants can tolerate as much direct sunlight as the crown of thorns. In fact, euphorbia milii thrives and blooms most prolifically when provided with maximum sun exposure.

Outdoors, full sun is best, though the plant can tolerate partial shade. Indoors, situate your plant in a south or west-facing window that gets 6+ hours of direct sun per day.

If you cannot provide enough natural light, supplement with a grow light positioned just a few inches above the plant. Crown of thorns exposed to insufficient light will become leggy and produce fewer blooms.

Temperature Needs

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These succulents originate from tropical environments, so they require warm temperatures year-round for best growth. Here are the ideal ranges:

  • Spring/Summer (Active Growth): 70-100°F
  • Fall/Winter (Rest Period): 60-70°F

While they can tolerate highs up to 100°F during the summer months, prolonged exposure to extreme heat will stress the plant. Aim to provide a consistent warm environment with plenty of airflow to prevent issues.

Avoid letting temperatures drop below 50°F, as this can kill the crown of thorns plant. They do not go fully dormant and cannot tolerate freezing conditions.

How to Water Crown of Thorns

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Like most succulents, crown of thorns should only be watered when the potting soil has completely dried out. Apply enough water to thoroughly saturate the roots, then allow the top 2-3 inches of soil to dry again before watering.

Some key watering tips:

  • Always use room temperature water, not cold. This can shock the euphorbia’s roots.
  • Water deeply and thoroughly to replicate heavy rainfall when you do water.
  • Allow excess moisture to drain fully from the pot to avoid soggy soil.
  • Consider using a moisture meter to determine when the soil is truly dry.
  • Reduce watering frequency from fall to early spring during the plant’s rest period.

Crown of thorns are highly susceptible to root rot if overwatered or planted in poorly draining soil. The potting mix should dry out completely between waterings during the growing season. Err on the side of underwatering rather than overwatering this drought-tolerant plant.

Fertilizing Needs

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Like other succulents, crown of thorns plants have very modest fertilizer requirements. Too much fertilizer can actually cause more harm than good.

During the active growing season from spring through fall, fertilize lightly once a month using:

  • A balanced 10-10-10 liquid fertilizer diluted to half strength
  • A controlled-release fertilizer formulated for cacti/succulents

Apply fertilizers when the soil is already moist and avoid getting any on the spiny stems. No fertilizer is needed during the plant’s rest period from late fall through winter.

Providing occasional supplements of chelated iron and other micronutrients can also encourage better flowering and richer colors.

Pruning Crown of Thorns

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One of the biggest benefits of growing crown of thorns is that they require very little pruning to look their best. The plants naturally grow into a dense, shrubby mound with interestingly twisted stems.

However, you may want to prune your euphorbia milii periodically for size control, shaping, or to remove any dead or damaged growth. Use sharp, sterilized pruning shears and protect your hands from the sharp spines.

The best time for major pruning is in early spring just before the plant’s peak growth period. You can prune off up to 1/3 of the plant to control size and shape it more compactly.

Pruning also encourages the plant to send out new flowering shoots and produce more blooms. Remove any long, leggy stems and thin out overcrowded interior growth to improve airflow.

After major pruning, hold off on fertilizing until you see active new growth emerging in a few weeks.

Blooming and Flowers

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One of the main appeals of growing crown of thorns is its incredible bloom displays. When provided with the right conditions, these plants can remain in constant bloom for months on end.

The small but vibrantly-colored flower clusters emerge directly from the stems among the spiny leaves. Flower colors range from yellows and oranges to bright pinks, reds, and even multi-colored bicolors.

Peak blooming occurs in late winter through summer when nights remain warm (above 60°F). The more sunlight the plant receives, the more floriferous it will be.

To encourage maximum blooming:

  • Provide at least 6 hours of direct sun or bright grow lights
  • Allow soil to dry out completely between waterings
  • Fertilize lightly during the growing season
  • Prune periodically to promote new flowering shoots

With the right care, you can enjoy the spectacular flower displays nearly year-round. Each vibrant bloom cluster lasts 4-6 weeks before fading.

Crown of Thorns Varieties

 Guide to Growing the Beautiful Crown of Thorns Plant

There are numerous named cultivars and varieties of Euphorbia milii available, featuring different growth habits, spine colors, and flower hues. Some popular options include:

  • ‘Buddha’s Temple’ – Dense, compact growth with fiery red-orange blooms
  • ‘Rani’ – Deep pinks and white bicolored flowers
  • ‘Vulcano’ – Brilliant red flowers on coral-colored stems
  • ‘Blackin Yellow’ – Unusual black stems with sunny yellow blooms
  • ‘Garda’ – Tri-color flowers in shades of red, pink, and white
  • ‘Granita Red’ – Large 2-inch flowers in bold crimson red
  • Rubra / Thai varieties – Bright pinks with reddish leaf spines

With so many showy flower colors available, it can be fun to collect multiple varieties of crown of thorns plants.

Potential Growing Problems

While euphorbia milii is generally a very low-maintenance plant, there are a few common problems to watch for:

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Yellowing Leaves – Usually a sign of overwatering or poor drainage. Reduce irrigation and ensure the potting mix is well-draining.

Leggy Growth – Caused by insufficient sunlight. Move to a brighter spot or add supplemental lighting.

Leaf Drop – Often occurs if the plant doesn’t get enough water or endures periods of extreme heat or cold stress. Adjust watering and temperatures accordingly.

Pests – Crown of thorns can occasionally suffer from mealybugs, spider mites or scale. Use insecticidal soap, neem oil or other approved pesticides to treat infestations.

Toxicity – The milky sap that oozes from broken stems can cause skin irritation for some people. Wear gloves when pruning and keep away from pets and children.

Root Rot – Possibly the biggest issue for indoor grown plants, root rot is caused by overwatering or poorly draining soil. Provide fast-draining soil and let it dry out fully between waterings.

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With proper light, water, and temperatures, you’re unlikely to experience many issues with this vigorous, long-lived succulent houseplant. Crown of thorns is regarded as one of the easiest flowering plants to grow indoors with its simple care requirements.

Whether you appreciate its boldly colored blooms, unique spiny texture, or simply want a low-maintenance plant, Euphorbia milii makes a great choice. Just exercise caution when handling to avoid its sharp spines. With some basic care, you’ll be rewarded with years of brilliant flowers and distinctive form from this striking plant.

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