Key Facts
- Succulent, spiny-stemmed shrub often grown as a houseplant in cool climates
- Showy small flowers are surrounded by colorful bracts and may appear much of the year in warm sites
- Prefers well drained soil and is drought tolerant once established
- Needs bright light and flowers best with several hours of direct sun each day
- Milky latex sap is an irritant and can cause skin and eye irritation
- Toxic to pets and people if ingested and may cause gastrointestinal upset
- Easily propagated from stem cuttings that are allowed to dry before rooting
- Often kept as a container plant where winter temperatures fall below its cold tolerance
Crown of Thorns is a spiny succulent shrub grown for long lasting colorful bracts that can appear for much of the year in warm sites. It performs well as a sun loving container specimen or a small outdoor shrub where frost is not a problem.
Identification
Succulent stems with sharp spines and small true flowers surrounded by bright bracts make this plant distinctive. Mature plants in garden settings commonly reach about 3 to 5 feet tall and often have a similar spread, while pot grown specimens are usually much smaller.
Where to grow and best uses
Use Crown of Thorns as a container plant for patios and bright windows where winter temperatures drop below frost. In warm frost free climates it works as a small flowering shrub in sunny beds or mixed xeric borders. The plant is drought tolerant once established but will flower best with several hours of direct sun each day.
Hardiness and site
Generally treated as frost sensitive and often listed for USDA zones 9 to 11. Bring container plants indoors if temperatures approach freezing because frost can cause dieback.
Soil and planting
Plant in a very well drained, light mix. Sharp drainage is essential because waterlogged soil leads to root loss and poor growth. For landscape planting space plants roughly 1 to 4 feet apart depending on cultivar and desired form.
Light and watering
Full sun to very bright light produces the most abundant flowering. In lower light the plant becomes leggy and flowers less. Water sparingly and allow the top few inches of soil to dry between waterings. Overwatering or poor drainage causes yellowing, soft stems and root decline while drier conditions favor compact growth and longer lasting blooms.
After flowering and pruning
Prune to shape after heavy flowering or to control size. Removing woody stems encourages branching and more compact habit. Wear gloves and eye protection when pruning because the milky sap is an irritant.
Containers and overwintering
Crown of Thorns is often kept in containers where it can be moved to bright indoor locations for winter. Use a free draining potting mix and a pot with drainage holes. Reduce watering in cooler months while still providing bright light.
Propagation
Propagate easily from stem cuttings. Allow cut surfaces to dry or callus briefly before placing in a very free draining mix. Always wear gloves and avoid getting sap on skin or in eyes.
Toxicity and safety
The plant produces a milky latex sap that can irritate skin and eyes. Ingestion may cause mouth and digestive upset and the species is considered toxic to dogs and cats. Keep plants out of reach of children and pets and consult local poison control or veterinary advice for exposures.
Frequently asked questions
- How fast does Crown of Thorns grow?
- Growth rate varies with light water and temperature. In warm outdoor conditions it can develop into a small shrub reaching about 3 to 5 feet over several years while container plants usually stay smaller. Pruning controls size and encourages branching.
- When should I plant Crown of Thorns outdoors?
- Plant outdoors after the risk of frost has passed and where the site receives several hours of direct sun each day.
- What soil mix is best for this plant?
- A light gritty or sandy mix with excellent drainage is best. Avoid heavy soils that stay wet.
- Can I grow Crown of Thorns indoors?
- Yes. Place it in the brightest window available and allow the soil to dry somewhat between waterings. Indoor plants may flower intermittently.
- Is the sap dangerous?
- The latex sap can cause skin or eye irritation and may cause gastrointestinal upset if ingested. Wear gloves and eye protection when handling and contact poison control for serious exposures.
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