Old man cactus care guide
Cephalocereus senilis
Also known as: Old man of Mexico, Cephalocereus
Pets and children
Caution advised
Sharp spines hide under the white hair and pierce whatever touches or chews it; keep it out of reach and see a veterinarian (or a doctor, for a child) if one sticks or a piece is eaten.
How often to water Old man cactus
- Spring–Summer (Mar–Sep)
- Every 14 days
- A summer grower from arid country: as a guide, water thoroughly about a week after the soil has dried through, pouring onto the soil so the hair stays dry.
- Autumn (Oct–Nov)
- Every 20 days
- As it cools, water roughly ten days after the soil dries, as a guide.
- Winter (Dec–Feb)
- Every 30 days
- Nearly dry, with only a very light moistening about once a month on a warm morning.
Light and placement for Old man cactus
Generally full sun and moving air year round; rain mats and dirties the white hair, so keep it under the eaves outdoors, and weak light makes the new growth thin with sparse hair.
Overwintering Old man cactus
Overwintering guide: 5°C (41°F) or above
As a guide, move it to a sunny indoor window before nights fall below about 5°C, keep it dry and away from heater drafts, and dryness makes the cold less damaging.
Fertilizing and repotting Old man cactus
Fertilizer
It grows slowly and needs little: diluted liquid feed about once a month from April to September, none in winter.
When to repot
Spring–Summer (Mar–Sep)
Common problems with Old man cactus
- Water trapped in the hair stays damp and starts rot.
- Left in the rain, the white hair yellows and mats together.
- Watered in a warm room over winter, the base rots.
Tips for growing Old man cactus
- Clean dirty hair with a dry brush rather than water.
- Growth is slow, so repotting every two or three years is enough.
- Pour water gently along the rim of the pot so none reaches the body.
These are AI-generated general guidelines. They vary with the variety, the placement and the pot size. For effects on pets or children, consult a veterinarian or a doctor.
Keep your plant log going
Greenery is a free app that keeps your plant care going, with watering reminders and photo records. Available on iOS and Android.
