Old man cactus Cephalocereus senilis
Old man cactus (Cephalocereus senilis) is an evergreen perennial shrub in the Cactaceae family, native to Limestone canyons of Hidalgo and Veracruz, Mexico. It grows 1–6 m (3.3–20 ft) tall and 30–50 cm (12–20 in) wide, wants full sun and low water, and is hardy to about 0 °C (32 °F). Space plants about 50 cm (20 in) apart.
Plan Old man cactus in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Old man cactus at a glance
| Type | Perennial shrub, evergreen |
|---|---|
| Family | Cactaceae |
| Mature height | 1–6 m (3.3–20 ft) |
| Mature spread | 30–50 cm (12–20 in) |
| Spacing | 50 cm (20 in) centre to centre |
| Sun | Full sun, at least 7 h of direct sun a day |
| Water | Low; drought tolerance high, waterlogging tolerance none |
| Soil pH | 7–8.5 |
| Cold hardiness | About 0 °C (32 °F) once established (roughly USDA zone 10) |
| Heat stress | Likely above about 42 °C (108 °F) |
| Flowering | about 1043–2086 weeks after planting, for 2–4 weeks |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Limestone canyons of Hidalgo and Veracruz, Mexico |
| Common in gardens of | 🇲🇽 Mexico, 🇺🇸 United States, 🇪🇸 Spain, 🇬🇧 United Kingdom, 🇩🇪 Germany, 🇯🇵 Japan |
Is Old man cactus toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Not poisonous; spines hide under the hair.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Old man cactus
No well-documented helpful pairing. Group it with plants that like full sun and low water.
Questions about Old man cactus
- How far apart should I plant Old man cactus?
- About 50 cm (20 in) apart, centre to centre. A mature plant spreads 30–50 cm (12–20 in).
- Does Old man cactus need full sun?
- Full sun: at least 7 hours of direct sun a day.
- How much water does Old man cactus need?
- Low water. Drought tolerance is high and waterlogging tolerance none.
- How cold-hardy is Old man cactus?
- It tolerates about 0 °C (32 °F) once established, roughly USDA zone 10.
- When does Old man cactus flower?
- About 1043–2086 weeks after planting, for 2–4 weeks.
- Is Old man cactus poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Not poisonous; spines hide under the hair.
- What grows well with Old man cactus?
- There is no well-documented companion pairing for Old man cactus. Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- LLIFLE Encyclopedia of Cacti and Succulents, LLIFLE (Living Encyclopedia), Italy
- IUCN Red List of Threatened Species, IUCN
Notes and assumptions
- A plant of dry, sunny places: grow it in gritty, free-draining soil and water deeply but rarely; cold and wet together kill it faster than frost or drought.
- In frosty climates it is a classic pot plant for a bright windowsill, put outside in summer.
- A single grey-green column draped in long, shaggy white hairs like an old man’s beard. Very slow; in the wild it can reach 15 m and only flowers when old, from a woolly zone near the top. Protected in Mexico.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Prickly pear (nopal) Opuntia ficus-indica
- Golden barrel cactus Echinocactus grusonii
- Saguaro Carnegiea gigantea
- Fishhook barrel cactus Ferocactus wislizeni
- Teddy-bear cholla Cylindropuntia bigelovii
- Engelmann's prickly pear Opuntia engelmannii
- Organ pipe cactus Stenocereus thurberi
- Mexican giant cardón Pachycereus pringlei