Red-headed Irishman

Mammillaria spinosissima

Family: Cactaceae (kak-TAY-see-ee) (Info)
Genus: Mammillaria (mam-mil-AR-ee-uh) (Info)
Species: spinosissima (spin-oh-SIS-ee-muh) (Info)
Synonym:Mammillaria spinosissima subsp. spinosissima
Synonym:Mammillaria auricoma
Synonym:Mammillaria pitcayensis
Synonym:Mammillaria centraliplumosa
Synonym:Mammillaria virginis


Cactus and Succulents

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Drought-tolerant; suitable for xeriscaping

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Suitable for growing in containers


6-12 in. (15-30 cm)


3-6 in. (7-15 cm)

6-9 in. (15-22 cm)


USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Sun Exposure:

Full Sun

Sun to Partial Shade

Light Shade


Plant has spines or sharp edges; use extreme caution when handling

Bloom Color:

Magenta (Pink-Purple)

Fuchsia (Red-Purple)

Bloom Time:

Late Winter/Early Spring

Mid Spring


Unknown - Tell us

Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

From seed; direct sow after last frost

Seed Collecting:

Allow unblemished fruit to ripen; clean and dry seeds

Unblemished fruit must be significantly overripe before harvesting seed; clean and dry seeds

Properly cleaned, seed can be successfully stored


This plant has been said to grow in the following regions:

Chandler, Arizona

Phoenix, Arizona

Huntington Beach, California

Mountain View, California

Pittsburg, California

Pleasant Hill, California

San Diego, California (3 reports)

Fort Walton Beach, Florida

Melbourne Beach, Florida

Las Vegas, Nevada

San Antonio, Texas

show all

Gardeners' Notes:


On Jun 27, 2016, Max64 from Las Vegas, NV (Zone 9a) wrote:

Grows extremely well here in the Las Vegas scorching heat. Both are planted in my SW facing yard but one is covered with burlap during the heat of the summer and the second one gets filtered light from the fronds of one of my palm trees. In the winter I just put a styrofoam cup on top for good measures just to be on the safe side.


On Mar 28, 2010, JohnTS71 from San Antonio, TX (Zone 9a) wrote:

I wonder if someone can changed the hardiness of this plant? I was afraid I was going to lose this with a hard freeze of 13 and several more in the low 20's but to my surprise I didn't!


On Nov 27, 2009, NancySLAZ from Sun Lakes, AZ (Zone 9a) wrote:

This plant grows very well for me, except I want to point out that you need to watch the sun exposure because mine got sunburned quickly on one side until I moved it. It prefers bright light but not direct sun on the plant.


On Apr 10, 2005, Xenomorf from Phoenix, AZ (Zone 9b) wrote:

The subspecies 'spinosissima' only rarely grows higher than 12 inches. It has dirty white spines and does not have the bristles in the axils most of the time.
The subspecies 'tepoxlana' has yellow spines.
The subspecies 'pilcayensis' has whiter spines and the stems can grow to 20 inches long/high. It might have some latex/bristles in the axils.
The flowers are purple-pink on all subspecies.

Another synonym of this plant is Mammillaria haasii


On Apr 9, 2005, cacti_lover from Henderson, NV (Zone 9b) wrote:

This cactus can grow to over 12" tall and 4" thick. Mostly solitary but can form pups on old plants. It is very variable due to it's wide area of origin in Mexico. The color of the spines are usually red or rust (common name Red headed Irishman), but can be white. Flowers are red to deep pink in color and are about 3/4" across.