How often should I water it?

Water sparingly during the growing season and keep it completely dry during winter.

Does it need full sun?

Yes, it requires bright, direct sunlight to maintain its hair growth and structural integrity.

Plant guide

Old man cactus.

Cephalocereus senilis

Pronounced sef-uh-loh-SEE-ree-us sen-IL-iss

Also known as bunny cactus, old man of Mexico, old-man cactus, white Persian-cat cactus, Old Man Cactus

Cephalocereus senilis — Photo by Carlos Lozano-Flores (CC BY) via gbif

The old man cactus is a striking succulent known for its long, shaggy white hairs that cover its columnar body. It grows quite slowly and brings a unique, fuzzy texture to any sunny collection. You will love how those silver locks catch the light in a bright window.

Another photo of Old man cactus — Photo by Codrin Bucur (CC BY) via iNaturalist

At a glance

Care level: Moderate
Plant type: Succulent
Light: Full sun
Indoor light: Direct sun
Water: Every 14 to 30 days
Mature size: Up to 40 to 50 feet (12 to 15 m) in habitat
Growth rate: Slow
Hardiness: USDA 9 to 11
Bloom time: Late spring to early summer

Care

Keep this cactus in a spot with plenty of direct sun to maintain its dense hair growth. Watch for signs of rot like mushy stems, which usually happen if the soil stays damp for too long. Use a well draining cactus mix to keep the roots happy and dry.

Watering: Allow the soil to dry out completely between waterings to prevent root rot.
Feeding: Feed with a balanced cactus fertilizer during the active growing season.
Pruning: Pruning is rarely needed, but you can remove dead or damaged sections with clean shears.
Repotting: Repot only when the plant becomes rootbound, as it prefers to stay in a snug container.
Soil: Sandy, well draining cactus mix
Soil pH: 6.0 to 7.5
Temperature: 10 to 35°C
Humidity: 10 to 30%
Drought tolerance: High
Lifespan: Perennial, can live for many decades
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage hole
Plant becomes top heavy and unstable
Soil no longer drains effectively

Safety

People: The plant is not toxic, but its sharp spines hidden beneath the hair can cause painful skin punctures.
Pets: This plant is generally considered non-toxic to cats and dogs.
Children: Keep this plant away from small children because the sharp, hidden spines can easily pierce skin upon contact.
Contact allergens: The stiff, needle like spines hidden under the soft hairs can cause mechanical skin irritation.
Airborne allergens: There are no known respiratory allergens associated with this species.
Edibility: This plant is not considered edible and may cause gastrointestinal distress if ingested.

How to identify it

Columnar stem covered in white hair
Sharp yellow spines hidden under hair
Slow growing cylindrical body
Dense woolly growth at the crown

Height: 1.5 to 6m
Spread: 0.3 to 0.6m
Leaves: green, evergreen
Flowers: pink, yellow, 5 to 9cm
Fruit: red, Late summer

Problems to watch for

MealybugsCommon
Root RotCommon
Scale InsectsUncommon
Spider MitesUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: seed, cuttings
When to plant: spring, summer
Overwintering: Move the plant to a dry, cool location and withhold all water until spring to prevent rot.
In containers: It is excellent for containers, provided you use a deep pot with drainage holes and a gritty cactus mix.

Seed Sowing

1. Sow seeds in a well draining cactus soil mix.
2. Keep the soil lightly moist until germination occurs.
3. Provide bright, indirect light for seedlings.

Stem Cuttings

1. Cut a healthy offset from the main plant.
2. Allow the cut end to callous for several days.
3. Place the cutting in dry, sandy soil until roots form.

Group this cactus with other slow growing desert plants that do not require frequent watering to prevent accidental overwatering.

Grows well with

Agave · They share similar requirements for sun and low water.
Aloe · These succulents thrive in the same well draining, arid conditions.

Similar species

Espostoa · It also features a dense covering of white hair.

Science

Family: Cactaceae
Genus: Cephalocereus
Order: Caryophyllales
Class: Magnoliopsida
Native range: Central Mexico
Conservation: This species is listed as endangered in its native habitat due to over collection and habitat loss.

It grows on steep limestone cliffs where its hair helps regulate temperature and moisture in a harsh environment.

Value to wildlife: nectar source
Pollinators: bats, moths
Uses: ornamental, xeriscaping, container specimen

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 1/9
Soil reaction: 7/9
Light: 8/9
Temperature: 7/9
Moisture: 2/9
Nutrients: 2/9

Taxonomy resolved against GBIF.

Questions people ask

How often should I water it?: Water sparingly during the growing season and keep it completely dry during winter.
Does it need full sun?: Yes, it requires bright, direct sunlight to maintain its hair growth and structural integrity.

Where the name comes from

The name Cephalocereus comes from the Greek word for head, referring to the hairy top, while senilis means old, referencing the beard like appearance.

Good to know

It is commonly called the Old Man Cactus because its white hair resembles an elderly person's beard.
In its natural habitat, it can grow up to 15 meters tall.
The hair density increases as the plant ages.
It grows very slowly, often taking years to reach a significant size.

Also in

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.