Crown of Thorns is a deciduous, herbaceous, perennial shrub with bright green leaves and greenish flowers. The flowers are enclosed within long-lasting and bright bracts of red or yellow. The plant is loose in form, spiny and irregularly shaped, with thick, black spines and its historic presence in the Middle East led to the belief by some that the stems of this plant had been used in Christ's crown of thorns, hence the common name. Crown of Thorns grows best in dry to medium moisture, well-drained soils in full sun. Because it does not like wet, cold soils or temperatures below 35 degrees F, it is an easy to grow indoor plant where it prefers a sunny location in soil-based potting mix. If grown outside in hot summer climates, provide the plant with midday shade and moderate moisture for better flower bloom.