This cactus can go outside in USDA zones 9 and 10. Native to Mexico, they need hot, dry climates and bright sunlight. The long hair is used by the plant to keep itself cool in its natural habitat. As an outdoor plant, they can get 45 feet tall but are generally slow growing as potted plants.
Use a cactus mix or blend of sand, perlite and topsoil for indoor cactus growing. Also, use an unglazed pot for growing old man cactus. This will allow the pot to evaporate any excess moisture. Old man cactus houseplants like their soil on the dry side and overwatering is a common cause of rot and disease.
Old man cactus needs a sunny, warm location but has few other needs. You should watch it carefully for pests, however, which can hide in the hair. These include mealybugs, scale, and flying pests.