Cleistocactus strausii, commonly known as the silver torch or wooly torch, is a perennial cactus of the family Cactaceae. Its slender, erect, grey-green columns can reach a height of 3 m, but are only about 6 cm across. The silver torch cactus (Cleistocactus strausii), also called a wooly torch cactus, is a columnar cactus that reaches up to 10 feet tall. The name silver or wooly torch comes from the wooly white appearance given by the fine needles and bristles that cover the stem. Mature plants have red flowers that bloom at the tops of the stems in spring or summer. It is native to mountainous regions of Department Tarija, Bolivia between 1,500 m and 3,000 m.
Water your torch cactus deeply and allow to slightly dry between waterings in the spring and summer time. Always water near the base of the plant and try to keep the column of the plant dry. They will not tolerate wet soggy soil or roots. Make sure to empty the saucer of all standing water. During the late fall and winter, you can go 4 weeks without watering your cactus.
Torch cactus needs as much sunlight as it can possibly get through the early spring and into late fall. Turn it frequently so a new section faces the light or it will begin to lean. It can handle indirect sunlight, but will not thrive as it will in full sun. Make sure to acclimate if moving outside into the direct sunlight. In the winter, if possible, move it to a cooler spot with less light so it can go dormant and rest.
Fertilize the silver torch with a low-nitrogen fertilizer during the active growth period. A slow-release fertilizer applied in the spring will be sufficient for the whole year. Follow the manufacturer's instructions for rates and application methods.
Plant silver torch cactus in soil amended with at least 50 percent sand. If the soil is clay-based, add even more sand to improve drainage. Alternatively, use 25 percent sand, 15 percent pea gravel and 10 percent peat moss or compost. Without drainage, the cactus will rot.
