Actual size and flowering may vary slightly based on season.
White Clumping Mammillaria
White Clumping Mammillaria is the twin-spine pincushion, a small cactus so densely covered in white spines that it looks white from a distance. Its heads cluster over time into a mound that can spread 2 to 3 feet. In the hot months, pink to carmine flowers open around the heads, followed by small red fruit. It suits pots, raised beds and cactus gardens.
Best for: wide pots and bowls, raised beds, and cactus gardens where a white mound stands out against dark rock.
Its heads cluster and fill a wide pot or bowl over the years. In a pot, water it 3 to 6 times a month during the warm season.
The dense white spines make the clump look white from a distance. Set it against dark gravel or green cacti for contrast.
Pink to carmine flowers open around the heads in the hot months. Small red fruit can follow.
It rots in soil that stays wet. It has handled the low 20s with no damage in Tucson, but cover it on hard freezes to be safe.
Wait about a week after planting before the first water. In a pot, water 3 to 6 times a month in the warm season and let the mix dry between drinks. Keep it dry in winter.
Feed a potted plant once or twice a year with a complete fertilizer, or monthly with a weak solution. Plants in the ground need none.
It can be damaged below about 25°F. On frost nights, cover it with frost cloth or a sheet that reaches the ground, not plastic, and take it off in the morning. Move pots under a patio roof.
It does best in full sun to lightly filtered sun. Light shade in the Valley summer helps.
Drainage test first. Dig the hole and fill it with water. If water is still sitting in the hole a day later, you likely hit caliche, clay or hard soil, so fix the drainage before planting. If it drains very fast, the soil is sandy. Standing water around roots is a common reason new plants fail.
Weed cloth. Cut it away from the planting hole and where the roots will spread. Remove any plastic sheeting completely, since it keeps water and air out of the soil.
Rock or decomposed granite with no soil underneath. Bring in soil close in texture to your native soil, mix it with the soil below, and build up enough depth for roots before planting.
If you can break through. Use a breaker bar, pick, or jackhammer. Dig through the caliche and break out the solid chunks. Backfill with the soil you dug out, with no compost or manure in the hole. Confirm drainage before planting.
If you cannot break through. Dig narrow holes through the hard layer beside the root ball, not under it, and refill them with the same soil, not gravel. If it still will not drain, plant on a low mound of the same soil.
Root ball. Check the outside edges for any roots circling around. Loosen or cut those so they grow outward. Do not break up the center of the root ball.
Depth. The top of the root ball should sit at or just slightly above the surrounding soil level. Planting too deep can lead to rot and kill the plant.
Drip emitters. At planting, put the emitters on the root ball, on different sides of the plant. After about 2 months, move them to the outer edge of the root ball. Over the first year, add emitters farther out toward the edge of the branches as roots grow. Once a plant is rooted, never water only at the trunk.
Why does this cactus look white?
Its heads are densely covered in stiff white spines, some with light brown tips. From a distance the whole clump looks white.
How big does it get?
Each head stays about 4 to 7 inches tall, but the heads cluster into a mound that can spread 2 to 3 feet wide.
When does it bloom?
In the hot months, with pink to carmine flowers around the heads. Small red fruit can follow.
Does it need shade in Phoenix?
It does best in full sun to lightly filtered sun. Light shade in a Phoenix summer keeps it from scorching.
How often should I water it?
In a pot, water it 3 to 6 times a month during the warm season, letting the mix dry between drinks. In the ground it needs less. Keep it dry in winter.
How cold can it take?
It is usually rated to about 25°F, and plants in Tucson have taken the low 20s with no damage. Cover it with frost cloth on hard freezes.
Should I fertilize it?
In a pot, feed it once or twice a year with a complete fertilizer, or monthly with a weak solution. Plants in the ground need no feeding.
Can I plant it in the ground?
Yes, once it is a good-sized clump, in soil that drains well. It still needs some water and care in the ground.
White Clumping Mammillaria for sale in Arizona, delivered to you
White Clumping Mammillaria (Mammillaria geminispina) is a pincushion cactus from central Mexico known for its white spines and wide clumps. This page covers its size, flowers, sun, water and cold in the Valley.
Sourced from trusted Arizona growers and delivered directly to your door, job site, or property. We deliver across the Valley and to nearby towns, and quote delivery anywhere else in Arizona.
What is white clumping mammillaria?
It is Mammillaria geminispina, the twin-spine pincushion from central Mexico, covered in white spines.
How big does it get?
Each head stays 4 to 7 inches tall, and the clump can spread 2 to 3 feet wide.
Twin-spine pincushion flowers
Pink to carmine flowers open around the heads in the hot months, followed by small red fruit.
Watering a potted pincushion in Phoenix
In a pot, water 3 to 6 times a month in the warm season. Keep it dry in winter.
Is it cold hardy?
It is usually rated to about 25°F. Cover it on hard freezes.
In the ground or in a pot
It suits pots and raised beds, and a large clump can go in the ground in soil that drains well.
We deliver across the Valley, from Phoenix, Scottsdale and Mesa out to San Tan Valley, Maricopa and Casa Grande, and up to Prescott, Sedona, Payson and Globe. See delivery areas and rates.