Ferocactus viridescens is a rare species of barrel cactus known by several common names, including coast barrel cactus and San Diego barrel cactus. It is native to southern California and northern Baja California, along a very restricted portion of the coast. Most of its native range is in San Diego County, California, where most of its habitat has already been removed, and much of the remaining habitat is threatened by development, agriculture, and other alterations in its habitat. This cactus is spherical, oblate, or nearly cylindrical, is usually wider than tall, and less than 30 centimeters in height. The flesh is bright green and arranged into several ribs covered in arrays of long spines. The spines stick straight out or may curve a bit, and are red when new, dulling to gray or tan. The cactus blooms in yellow to greenish flowers with red or pink scales. The fruit is yellow or red. Although wild populations are in the immediate vicinity of the coast, it can be grown inland in areas that do not experience regular freezing. It makes a great specimen for the dry coastal garden in the southern counties.