Native to Argentina and Bolivia, this shrubby columnar cactus has shaggy fine white hair that protects it from the night frost and the sun in the morning of high altitudes on arid mountains.  

The Oreocereus trollii can form a small clump of stems, each reaching up to 2 feet tall and 4 inches wide, with long, yellow-to-red hair-like radial spines that poke out of the wool. It grows slowly, adding new growth rings each year, which can be seen as distinct bands on its stem. With time, it develops a majestic presence in your garden or indoor space.  

The Oreocereus trollii flowers bloom during late spring to early summer, with stunning pink or violet-red flowers that emerge from the top of the plant. These semi-tubular blooms add a vibrant splash of color to its otherwise muted appearance, creating a delightful contrast against its shaggy white hairs. 

When it comes to Oreocereus trollii care, it loves full sun exposure. It is best to plant it in an area where it receives good bright light for at least 6 hours a day. Water the old man of the mountain cactus sparingly to prevent root rot and ensure the soil is fully dried out between two waterings. Avoid allowing the cactus to sit in water, as overwatering can cause it to die. During the winter months, it benefits from a period of dormancy with cooler temperatures and reduced watering.  

The Oreocereus trollii grows happily in a specialized well-drained soil mix. For outdoor cultivation, it is best suited for USDA zones 8 to 11. In colder regions, it is ideal for planting them indoors in warm temperatures between 50 - 75 F.  

To propagate this old man of the mountain cactus, you can collect its seeds or take stem cuttings. To harvest seeds, allow them to mature and dry before harvesting. For stem cuttings, choose a healthy stem and let it be callous for a few days before planting it in well-draining soil with lightly moist soil.  

With its unique appearance, this cactus makes for an eye-catching addition to rock gardens, xeriscapes, or desert-themed landscapes. Its shaggy white hair creates a striking contrast against the surrounding greenery or other desert plants. People often confuse the Old Man of the Mountain cactus, with the Old Man of the Andes cactus because of their similar names and the presence of shaggy white hairs on their bodies.  

So, if you're looking for a cactus that will add a touch of whimsy and intrigue to your garden, the Oreocereus trollii, the Old Man of the Mountain cactus, is definitely worth considering.