Here are two patio-plant varieties, both hardy to 30F, grown by Altman Specialty Plants. Opuntia violacea santa-rita . Native to Texas, Arizona and northern Mexico. Grows to 3 feet. Round pads have a bluish tint and in winter or times of drought turn red or purple.
Flowers are yellow with red centers.
Many variations exist and flower color ranges from yellow to white. North and South America and the West Indies. The characteristic jointed stems can resemble flat paddles, cylinders or globes. Some species are mere groundcovers reaching no higher than a few inches, others are 20-foot trees. Many are suitable as landscape or potted plants.