Mammillaria Spinosissima “Red-Headed Irishman” Care & Buying Guide

Mammillaria Spinosissima


Light requirementsHigh
Water requirementsLow
Ease of careEasy
Zone9a to 11b
Temperature resistanceMildly frost-hardy
Growth speedMedium
Indoor growingSuitable


Taking Care Of Mammillaria Spinosissima “Red-Headed Irishman”

Ideal conditions

Mammillaria Spinosissima “Red-Headed Irishman” loves temperatures on the warmer side (though it is somewhat frost-hardy), requires little water, and needs partial to full sunlight to thrive. The Red-Headed Irishman will do best outdoors, though it may be kept indoors as well.


Just like many other succulents, Mammillaria Spinosissima “Red-Headed Irishman” should be watered only when its soil is dry to the touch. This cactus is drought-resistant and requires little water. Do not overwater the Red-Headed Irishman cactus since this may lead to root rot.

During late fall and winter, the Red-Headed Irishman gets dormant and doesn’t need as much water as during its growing season. It can do well without any water, but you may very occasionally mist it. Do keep in mind that in winter, it’s much easier to overwater this cactus.

Where to plant

Plant the Red-Headed Irishman in a fast-draining cactus potting mix. For better drainage, add some perlite or pumice in perhaps a 1:1 ratio with the cactus mix.

Given that this cactus likes partial to full sun, it’s best to grow outdoors. With the sun easily accessible outdoors, the Red-Headed Irishman will get plenty of light and show great growth.

On hotter days, you should move the pot with the cactus to a shaded location, but only temporarily. Once the hottest hours of the day have passed, you should be able to move the pot back to its regular location.

If growing the Red-Headed Irishman indoors, then place it on a sunny window sill to ensure adequate light, but do make sure to shade the plant on very hot days.

Mammillaria Spinosissima “Red-Headed Irishman” should do well outdoors during milder winters, but if the temperatures get low in your area, then be sure to bring the plant inside to protect it from freezing.

General care information

During spring and summer, fertilize the soil of the Red-Headed Irishman with a cactus fertilizer mix diluted to half strength. Depending on the fertilizer used, fertilize the cactus once every 4-8 weeks.

Mammillaria Spinosissima “Red-Headed Irishman” is a relatively fast grower and grows to be up to 12 inches tall, so you’ll need to repot it occasionally. You may repot the cactus as needed, but do so preferably every spring or summer.

Frequent repotting will allow you to inspect the cactus’ roots and treat damaged ones if any. Besides, some people believe that introducing cacti to fresh soil can boost their growth.

Before repotting, allow the plant to dry so that you can easily remove it from the pot. Inspect the roots and cut away any that are rotten or otherwise damaged. After planting the cactus in new soil, allow it to sit for around a week without water so that it can recover from the stress of repotting.