Haageocereus tenuis, commonly known as Thin Columnar Cactus or Long Spined Cactus, is a slow-growing succulent native to the arid regions of Peru, particularly found on dry, rocky hillsides and coastal deserts. This cactus typically reaches a height of 3-6 feet (0.9-1.8 meters) and a width of 1-2 feet (0.3-0.6 meters). It has a cylindrical form with elongated stems covered in long, sharp spines. The white, nocturnal flowers emerge in the summer and are quite showy, attracting pollinators such as moths.

The Thin Columnar Cactus is valued for its striking vertical form and the contrast its spines provide against other plants in xeriscapes and rock gardens. It is well-suited for cultivation in arid or semi-arid climates, requiring minimal maintenance. Gardeners appreciate its drought tolerance and its ability to thrive in full sun with very low water needs. It prefers a fast-draining sandy soil to prevent root rot. While it is generally pest-resistant, overwatering can lead to fungal diseases. This cactus is not known for being invasive but should be handled with care due to its long spines.CC BY-SA 4.0