Actual size and flowering may vary slightly based on season.
Mammillaria melanocentra
Mammillaria melanocentra is a stout, blue-green cactus from northern Mexico with big, four-sided bumps and a long black center spine on each one. It usually stays a single, slightly flattened head about 6 inches tall. In spring a full ring of dark pink flowers circles the top. It suits pots, dish gardens and small cactus beds.
Best for: pots, dish gardens and small cactus beds where its black spines and pink flower ring can be seen up close. It usually stays a single, stout head.
It usually stays a single head about 6 inches tall and 4 to 6 inches wide. That size suits a small pot or a dish garden.
In spring a full ring of dark pink flowers circles the top of the plant for several weeks. Pink to red fruit can follow.
Its long black center spines and blue-green body stand out next to golden or white-spined cacti in a small bed.
It can be damaged below about 25°F, so cover it on frost nights. Wet winter soil can rot it. Give it light shade in the Phoenix summer.
Wait about a week after planting before the first water. Then water about every other week while nights stay above 60°F. Once it is rooted, water when the soil has dried out in summer. Keep it dry in winter unless the winter is very dry.
It grows in full sun to light shade. In Phoenix, give it light shade in summer so it does not scorch.
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 on cold nights.
Use a pot with a drainage hole and a gritty cactus mix with plenty of pumice, perlite or coarse sand. Water it when the mix is dry, and keep it drier in winter.
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.
How big does Mammillaria melanocentra get?
It usually stays a single head up to about 6 inches tall and 4 to 6 inches wide. It grows slowly and keeps a stout, flattened shape.
What are the black spines?
Each bump carries a long black center spine that turns gray with age. The name melanocentra means black center, so there is nothing wrong with the plant.
When does it bloom?
It blooms in spring with a full ring of dark pink flowers around the top. Keep it in good light so it blooms.
Does it need shade in Phoenix?
It grows in full sun to light shade. In Phoenix, give it light shade in summer so it does not scorch.
How often should I water it?
Wait about a week after planting, then water about every other week while nights stay above 60°F. Once it is rooted, water it when the soil has dried out in summer. Keep it dry in winter.
How cold can it take?
It is usually rated to about 25°F, and some growers report colder. On frost nights, cover it with frost cloth or a sheet down to the ground, and move pots under a patio roof.
What soil does it need in the Valley?
Plant it in soil that drains fast, like sandy or gravelly native soil, with no compost. If you hit caliche, break through it so water drains, or choose another spot.
How do I handle it without getting stuck?
Wear thick leather gloves, and wrap the plant in folded newspaper or cloth to lift it. Keep it away from spots where kids play.
Mammillaria melanocentra for sale in Arizona, delivered to you
Mammillaria melanocentra is a cactus from northern Mexico, named for its black center spines. Below is what to expect in a Valley pot or bed: size, sun, water, cold and flowers.
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What is Mammillaria melanocentra?
It is a stout, blue-green cactus from northern Mexico. Each large bump carries a long black center spine.
How big does Mammillaria melanocentra get?
It usually stays a single head about 6 inches tall and 4 to 6 inches wide, and it grows slowly.
Mammillaria melanocentra flowers
In spring a full ring of dark pink flowers circles the top of the plant. Pink to red fruit can follow.
Growing Mammillaria melanocentra in Phoenix
Plant it in fast-draining soil in full sun to light shade, with light shade in summer. Keep it dry in winter.
Is Mammillaria melanocentra cold hardy?
It is usually rated to about 25°F. Cover it with frost cloth on frost nights, and keep the soil dry through winter.
Mammillaria melanocentra in a pot
It is a good pot plant. Use a gritty cactus mix and a pot with a drainage hole, and let it dry between waterings.
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