Old Man Cactus (Cephalocereus senilis): White-Haired Columnar Cactus

Overview

Old Man Cactus (Cephalocereus senilis) is a columnar cactus from eastern Mexico, famous for its dense covering of long, white, silky hairs that conceal the green stem and sharp spines. The hairs protect from intense sun and cold. It grows slowly to 20–50 feet in habitat, but stays smaller in pots. At maturity (10–20 years), it develops a lateral cephalium (flowering zone) of dense wool and bristles, from which pink, nocturnal flowers emerge. A unique, tactile specimen for collectors. The hairs are longest on young plants.

Key Features

• Stems: Columnar, green; concealed by long white silky hairs.
• Hairs: Modified spines; protect from sun/cold; longest on youth.
• Cephalium: Dense wool/bristles at maturity; flowering zone.
• Flowers: Pink, nocturnal; from cephalium.

Care Guidelines

Light

Full sun. Encourages hair growth.

Water

Low. Water when dry. Keep dry in winter.

Soil

Very well-drained, gritty cactus mix.

Hardiness

USDA zones 9–11. Protect from frost.

Taxonomy

Family:	Cactaceae
Genus:	Cephalocereus (sef-uh-low-KER-ee-us)
Species:	senilis (SEE-nil-is)