Usually grown as a potted plant, Crown of Thorns also does well in gardens. If you want to keep the neighbors' dogs away, you can't beat it. It grows quickly, and propagates easily. The plant is a member of the Euphorbia family and a relative of the Mexican Euphorbia. This is one of the few commercial uses of cacti.
Most cacti prefer full sun and sandy soil.
They like dry air but can deal with average humidity. Cacti need some, but not much, water. Water infrequently, but soak the plant when you do. Overwatering will rot the roots and kill the plant. About the only pest to attack cactus is the caterpillar, which will take the leaves off.