Stenocereus pruinosus is a large shrubby or tree-like cactus with a distinct trunk from which the branching stems arise. It grows up to 16 feet (4.9 m) tall and 10 feet (3 m) wide. Stems are gray-green, often with powdery bloom near the apex, up to 4 inches (10 cm) across. They have 6 to 10 very high ribs lined with areoles. Spines are grey to brownish and up to 1.2 inches (3 cm) long. Each areole bears 1 to 4 central and 5 to 8 radial spines. Flowers are white, funnel-shaped, and appear on new growth at the stem tips in summer. Fruits are egg-shaped, up to 3.2 inches (8 cm) long, and change color from yellow to orange-green and purple.

Like most cacti, Cereus are fairly low-maintenance and hardy. Ensure they receive enough water without becoming waterlogged, especially during the summer, and fertilize them for the best results. If the roots have become black or overly soft, the cactus could be experiencing root rot. Cut away the affected parts and replant. Most gardeners interested in cacti should be able to cultivate these without much problem.

It may become necessary to repot your Cereus if it outgrows its container. If so, ensure the soil is dry and remove the pot. Knock away old soil, prune away any rotted or dead roots, then replace it in a new pot and backfill it with new soil. Ensure not to overwater cacti planted in new pots, as this can lead to root rot. It should be left dry for about a week and then watered lightly.

These cacti propagate quite easily from cuttings. Simply sever a branch and replant in moist, well-drained soil.