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Plant Profiles / Old lady cactus
Photos: Wikimedia Commons
Old lady cactus
Mammillaria hahniana · Old woman cactus
A small, round cactus covered in soft white hairs, crowned each spring with a ring of bright pink flowers.
Full sunLight
Every 2–3 weeksWater
Very easyCare level
Care at a glance
Light
Full sun
ShadeFull sun
Bright light with direct sun.
Water
Every 2–3 weeks
DryWet
Water only when dry. Avoid wetting the hairs.
Humidity
Low
LowHigh
Dry air.
Temperature
5–35°C (41–95°F)
CoolWarm
Keep dry in cold weather.
Growth
Slow, clustering
SlowFast
Grows 10–20 cm.
Soil
Cactus mix
LeanRich
Gritty mix.
Fertiliser
Twice a year
RarelyOften
Diluted cactus fertiliser.
Pet safety
Non-toxic
SafeToxic
Non-toxic.
About this plant
Native to central Mexico, the old lady cactus gets its name from its white, hair-like spines. It often forms clusters with time and flowers reliably, even when small.
Best spots
Sunny windowsills, cactus bowls and sunny balconies.
Plant facts
| Botanical name | Mammillaria hahniana |
| Family | Cactaceae |
| Origin | Central Mexico |
| Plant type | Globular cactus |
| Mature size | 10–20 cm |
| Growth rate | Slow |
| Spines | Soft white hairs |
| Flowers | Ring of pink-purple flowers |
| Toxicity | Non-toxic |
| Propagation | Offsets or seed |
Seasonal care calendar
J
F
M
A
M
J
J
A
S
O
N
D
Flowering
Active growth
Keep dry
FloweringActive growthKeep dry
Based on Southern Hemisphere seasons.
Troubleshooting
| No flowers | Needs a cool, dry winter rest. |
| Matted, dirty hairs | Water the soil, not the plant. |
| Soft base | Overwatering. |
| Stretching | Not enough light. |
| Mealybugs | Treat with alcohol. |
Common questions
How do I get it to flower?
Give it a cool, dry winter.
Are the hairs spines?
They're modified spines, soft to look at but with sharp spines underneath.
Is it pet safe?
Yes.
Does it cluster?
Often, with age.
