Trichocereus pasacana is a tree-like cactus that gets up to 10 meters tall though the average height is usually a lot less. It can reach a diameter of 30-45 centimeters and has between 18-22 ribs. It has a lot of small, needle-like spines that can get up to 10-15 centimeters in length. The mature form looks a lot different to its early appearance. The spines are yellow in color and their length is decreasing during the life cycle of the plant. Old plants tend to have lesser spines that young ones and the early spine form is a lot stronger that the adult form.