How to grow and care for it
Crown of Thorns do well in even the poorest soil, provided that it is well drained and does not remain moist. It prefers a location in full sun but will tolerate some shade for a portion of the day. It is a good choice for a seaside location with salt spray or soil with high salt content. If you are growing your Crown of Thorns as a house plant, place it in a south-facing or west-facing uncovered window to ensure it receives maximum sunlight. Although the plant is drought tolerant, you can induce your plant to retain its leaves and blooms frequently by watering it regularly and giving it an occasional dose of fertilizer. Be sure to check the fertilizer labels and choose a basic, balanced formula without added micro-nutrients, since the plant is sensitive to boron.
The plant benefits from light pruning as it matures. At the end of each grow season, remove some older, leafless branches to stimulate new growth in spring. Clear away dead leaves and any dropped, matted flowers to allow the soil to dry well and reduce the likelihood of fungal disease. If you notice any brown stems or leaves on your plant, cut these back to a healthy tissue to prevent rot from spreading through the plant. If you grow your plant indoors and wish for it to move outside for warmer weather, keep it in partial shade for a week or two until it assimilates to bright sunlight.