Old Man Cactus

Old Man Cactus (Cephalocereus senilis) is a tall, columnar cactus covered in long white hairs that soften the look of its spines. In habitat it can eventually reach several metres, while container-grown plants are usually much smaller; [North Carolina State Extension](https://plants.ces.ncsu.edu/plants/cephalocereus-senilis/common-name/old-man-cactus/) describes typical houseplants as roughly three to four feet tall and lists a wild range of three to forty feet. ## Light and growth Give this cactus bright light with direct sun, using a sunny window indoors or a warm, open site outdoors in suitable climates. It grows slowly and needs space for its upright column. A pot with a drainage hole and a coarse, fast-draining cactus mix helps prevent water from collecting around the roots. The unusual white covering consists of modified spines; avoid handling the plant directly. ## Water and hardiness The species is native to Mexico and is listed for USDA zones 9–11. Water thoroughly during active growth, then let the mix dry before watering again. In winter, reduce watering and withhold fertilizer while growth slows. Indoor plants are generally more compact than specimens grown in the ground. ## Maintenance Use gloves and tools when repotting, and handle by the container rather than the hairy stem. Repot only when needed, keeping the same planting depth and refreshing the free-draining mix. Protect outdoor plants from frost and prolonged cold rain; bring container plants into bright shelter before temperatures fall below their safe range.