Cereus hexagonus is a shrubby or tree-like cactus that usually branches from near the ground and grows into candelabra form with a short main stem. It can reach up to 50 feet (15 m) in height, while the main stem can reach up to 16 inches (40 cm) in diameter. The branches are greyish-green, blue-green to light green, and usually have six ribs and 8 to 10 spines per areole. They can grow up to 6 inches (15 cm) in diameter. The young spines are brown and become white or gray with age.
The flowers are white, funnel-shaped, and can reach up to 10 inches (25 cm) in length. They appear from spring to summer and open at night. The edible fruits are pale red, egg-shaped, and can grow up to 5.2 inches (13 cm) long.
