How Do You Tell If You’re Overwatering Mammillaria Cactus?

Mammillaria is the genus name of an attractive type of succulent cactus plant native mostly to the southwest United States (southern New Mexico and western Texas) and Mexico, with some having naturalized in the Caribbean.

There are around 300 species within the genus Mammillaria.


This plant is also known by its common name, Nipple or Pincushion Cactus plant.

Many of the individual Mammillaria species look so much alike as to be almost indistinguishable. Others vary greatly in appearance and cultivation needs.

In this article, we discuss the care and uses of this interesting plant and share advice on selecting the right mammillaria cactus types of the many species available for your home, greenhouse, patio, yard, garden, or windswept desert property.

Mammillaria Cactus Quick Care Tips

  • Botanical Name: Mammillaria crinita
  • Common Name(s): Pincushion Mammillaria Cactus
  • Synonyms: Mammillaria crinita subsp. crinita
  • Family & Origin: Cactaceae family, native to Mexico
  • Growability: Easy to grow
  • Grow Zone: USDA zones 9-11
  • Size: Grows up to 6 inches tall and 6 inches wide
  • Flowering: Produces pink or white flowers in the spring
  • Light: Needs bright, direct sunlight
  • Humidity: Prefers low humidity
  • Temperature: Thrives in warm temperatures between 60-80°F
  • Soil: Well-draining soil mix
  • Water: Water sparingly, allowing soil to dry out between waterings
  • Fertilizer: Fertilize once a month during the growing season with a cactus fertilizer
  • Pests & Diseases: Susceptible to mealybugs, spider mites, and root rot
  • Propagation: Propagate through offsets or seeds
  • Plant Uses: Makes a great addition to a cactus or succulent garden, can also be grown indoors as a houseplant.

What Are Cactus Mammillaria Related To?

The pincushion cactus is often confused with several other types of small cacti (e.g., Neolloydia, Epithelantha, and Coryphantha). This confusion has led to as many as 400 different species being mistakenly identified in the past.

A great deal of meticulous research in the field, along with genetic analysis has gone into sorting out this jumble.

Now botanists are confident that the genus contains around 300 species.

You won’t find most of the many species offered in nurseries, garden centers, and shops.

The varieties for sale as houseplants are typically small and grow close to the ground in the wild. 

To recognize a true Mammillaria cactus, look for its spirally arranged, succulent nipple-shaped tubercles.

Interestingly, the spines of true cactus Mammillaria are arranged according to the Fibonacci sequence.

This means that each row of tubercles is equal in number to the sum of the two rows immediately above it.

When you view the pincushion cacti from above, you should notice that it has a very organized and orderly appearance.

Growing Mammillaria Cactus Facts

Size & Growth vary greatly depending on the species. Some Mammillaria top out at an inch high, others at a foot high.

Flowering & Fragrance vary greatly from one pincushion cactus to another. All grow in a crown-like formation surrounding the top of the plant. Moreover, it has central spines or cushion-like areoles of blooms and is about 0.4 to 8″ inches in diameter stems. 

Light & Temperature: Generally speaking, Mammillarias like warm temperatures (50° to 85° degrees Fahrenheit) and bright light. It thrives in full sun or partial shade exposure. It needs at least 2 to 6 hours of direct sunlight daily.

Watering & Feeding should be sparse year-round. During the spring, summer, and early fall, water your Cactus mammillaria thoroughly when the soil is almost dry.

During the winter, reduce watering by half. Provide a half-strength feeding of a balanced cactus fertilizer at the beginning of spring and toward mid-summer.

Potting Soil & Transplanting: The pincushion cactus prefers a fairly rich, well-draining cactus mix. Repot or transplant infrequently, as these plants do well when slightly root-bound.

Grooming is Simple: Keep an eagle eye out for any signs of rot, and cut it away immediately if you notice it. Otherwise, separate and repot pups when they become overcrowded.

USDA Hardiness Zone: Mammillaria is generally hardy in USDA zones 8 to 11; however, this may vary from species to species. Refer to the USDA Plant Profile Pages for more specific information.

The various pincushion cactus species are native to habitats ranging from low desert to both cold and tropical forest settings. Their natural range extends across the southwestern US and throughout Central America.

Mammillaria Cactus Care

Mammillaria cactus care for this genus of cacti varies greatly depending on the species you select and how you choose to use this succulent plant.

Rugged outdoor plants require very little care. Keeping a cactus Indoors is another matter entirely.

When you keep indoor cactus, be sure to set up a sunny location in a room with a south-facing window during the wintertime.

This setting provides the most sunlight. A window location is typically a bit cooler than the rest of the room, and this cool temperature during the winter months is necessary to spur Mammillaria to bloom during the growing season.

In the spring and the summertime, vary the location to provide your Mammillaria cacti with the most light and heat.

Giving your plant an outdoor vacation in direct sunlight is a good idea.

How Often Should Indoor Mammillaria Cactus Be Watered?

During the growing season, let the top couple of inches of soil dry out before watering these succulent plants. Water the plant thoroughly, allowing excess water to run off. 

If your Spiny Pincushion cactus has a drip tray, be sure to empty it. These plants should never stand in water.

How Long Can You Go Without Watering A Mammillaria Cactus?

In wintertime, cut back on watering. You should only water about once a month and then quite sparingly. Just give the plant enough water to prevent it from shriveling up. 

Be sure to keep your plant at about 50° degrees Fahrenheit during the winter and provide plenty of indirect light.

How Much Fertilizer Does A Mammillaria Need?

You can fertilize your Mammillaria with a specially formulated cactus fertilizer or a very weak solution of houseplant fertilizer that is low in nitrogen and high in potassium and phosphorus.

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Don’t overfeed your cactus, as this will encourage green growth and discourage blooming.

What Type Of Potting Soil Is Best For Mammillaria Cactus?

When you repot your pincushion cactus, you can use a prepared cactus/succulent potting soil or make up your own cactus mix to get the soil texture you want using a combination of one part potting mix, one part coarse builder’s sand, and one part loam. Adding pumice will also help improve drainage.

Moreover, ensure the soil mix has good drainage and aeration. 

When And How Often Do Mammillaria Bloom?

Only mature Mammillaria blooms, and when they do bloom, they display an attractive crown of flowers surrounding the top of the plant.

These lovely flowers appear at the top of the stem, which provides a pop of color when blooming. 

Close up of Mammillaria lenta white flowerClose up of Mammillaria lenta white flowerPin
Flowers of Mammillaria lenta up close

Flowers come in a wide range of colors, sizes, and shapes, depending on the species of Mammillaria.

Some of them are richly fragrant and very attractive to hummingbirds and other pollinators.

How Often Do Mammillaria Bloom?

In an ideal outdoor setting, these plants produce buds during one growing season and then go dormant through the winter and into the spring and early summer.

After the first summer rain, the pincushion cactus opens, and the flowers last for about seven days. Healthy, happy Mammillaria may bloom several times during the growing season, always following rain.

Flowers may mature into edible fruits. Some are tart and tasty, while others are quite bland. Generally speaking, these fruits are very small, and it is hard to gather enough to provide much nutrition.

How Long Does It Take Mammillaria To Mature?

It can take many years for a pincushion cactus to mature, so you may not see a flowering plant for a very long time. 

You should also realize that desert cactus kept indoors may never bloom because they simply cannot get enough light. 

The only way of being sure you are getting a mature plant is to purchase one that is already in bloom.

When Should Mammillaria Cactus Be Repotted?

You should not need to repot your cactus more than once every couple of years. They do well with crowded root systems but will need repotting if the cactus becomes top-heavy or the pot becomes overcrowded with offsets.

Naturally, you should replace the potting soil every couple of years because it will become depleted, and salts may build up from water over time.

It is best to repot at the start of the growing season, but it may be done almost any time of the year. 

Don’t water before repotting the cactus, as it is easier to knock away dry soil from the roots, and potting in dry soil helps prevent the risk of root rot.

Examine the roots carefully and cut away any portions that appear to be dead or rotten. Treat the areas you cut with a spritz of hydrogen peroxide or a fungicide. Learn more about using Hydrogen Peroxide for plants.

Put the plant into its new pot with drainage holes and surround it with your prepared cactus mix. Spread the roots out to give them room to grow. 

Don’t water right away. Wait about a week, and then give the plant a light watering. Doing this helps prevent root rot.

Other Mammillaria Cactus Varieties to Grow:

How Do You Propagate Mammillaria?

These cacti are easy to multiply via two propagation methods: seed or offsets (pups) from the mother plant. 

The pincushion cactus spring up in clusters around the base of the parent plant. To propagate them, remove them carefully using a very sharp, sterile blade, or simply pull them away.

Lay the offsets on a clean paper towel in a sheltered, airy setting for a few days. This will allow a callus to form over the cut or area where the pup was separated from the parent plant.

When a callus has formed, you can put the pup into its own pot. Keep it in a warm, sheltered place with bright, indirect sunlight until it takes root. 

This may take a few days or a few weeks. Once the plant has established roots, you can treat it just like the mature parent plant.

What Are Some Common Pests & Problems Affecting Mammillaria?

Most problems with cactus grown as houseplants involve bacterial or fungal diseases that are caused by excessive watering.

This is why it is very important to establish a sparing watering schedule and observe your plants carefully for any signs of rot.

These include black spots around the base of the plant and mushy flesh.

In addition to problems caused by overwatering, common houseplant pests are sometimes problematic. Among these are:

It can be very hard to get these pests under control once they are established because they are very small and hide quite effectively. 

Some of these pests have protective coatings that make it difficult to reach the actual insect with a pesticide or natural treatment.

To make matters worse, many common plant pests have developed resistance to commercial pesticides.

That’s why it is smart to maintain an Integrated Pest Management (IPM) strategy when dealing with any and all garden and houseplant pests.

Follow These 9 Smart IPM Tips!

#1 – Keep your plants healthy by providing the right environment and the correct care. Healthy plants are better able to resist disease and pests.

#2 – Always quarantine new plants for at least three weeks to avoid bringing in illness or hitchhikers. If you discover problems with a new plant, keep it separate and treat it or toss it.

#3 – Use natural treatments first. Spider mites and mealybugs can often just be washed off with a strong spray of water. Remember to cover the soil with plastic to prevent overwatering your cactus in the process.

#4 – Examine and clean the roots of cactus when repotting or transplanting. Root mealybugs can be washed off the roots with a strong spray of water. Blot excess water from the roots and allow them to air dry for a few hours before continuing with repotting or transplanting.

#5 – Examine your cacti often for signs of scale and mealybugs. If you see just a few, you may be able to remove them easily with a cotton swab dipped in rubbing alcohol.

#6 – You can spray your cacti occasionally with a diluted rubbing alcohol solution. Mix up one part alcohol with three parts water for a spray that will help deflect these pests. Be sure to test spray a small spot on the plant before spraying the entire plant. Some cacti are sensitive to rubbing alcohol.

#7 – Trap fungus gnats with yellow sticky traps or set up small jars of apple cider vinegar (ACV) to trap them. To do this, you’ll need a small jar with a lid. Punch small holes in the lid (or use an old spice bottle that already has a lid with holes).

Pour about half an inch of ACV into the jar and screw on the lid. Place the jar among your plants. Gnats will fly in to get the ACV and won’t be able to get out, so they’ll drown in the ACV.

#8 – Make milder insecticides your first choice, applied sparingly and only when necessary. Neem oil and pyrethrins are good choices.

#9 – If you have a problem with pests that are hard to reach with sprays, use systemic insecticides such as acephate and imidacloprid. Follow the packaging instructions carefully.

How Do You Tell If You’re Overwatering Mammillaria Cactus?

Remember, these cactus plants don’t just tolerate drought; they need it. Their roots are very susceptible to rot, and it’s easy to kill them with too much water.

It may not seem that way at first, though. When a cactus first receives too much water, it may become very plump and begin putting out new growth.

Even when this is happening above ground, the roots are sure to be suffering under the soil.

When cactus roots become waterlogged, they start dying and rotting. Gradually, the rotten roots cause the seemingly healthy plant to start deteriorating.

The flesh becomes discolored and begins to soften. When this starts to happen, it may be too late to save the plant.

That’s why it is so important to monitor your cactus carefully and look for soft, discolored spots around the base of the plant.

How Do You Save An Overwatered Mammillaria Cactus?

If your cactus is showing signs of rot around the roots, you must remove it from its pot and use a sharp, sterilized blade to cut away the rotten parts.

Work from the bottom up, removing thin slices until you reach fresh, unaffected flesh.

Seal off the open cut with cornstarch, and allow the cutting to dry on a paper towel for a period of several weeks.

If your cutting is going to survive, it will produce a few roots during this time.

When this happens, carefully brush away the cornstarch and provide the cutting with its own new pot and fresh cactus mix.

Best Uses For Mammillaria Cactus Indoors or Outdoors

There are so many different types of Mammillaria cactus that, no matter what your setting or purpose, you can surely find a variety to suit your needs.

Some species are quite delicate and suited to a sheltered indoor setting. Some are rugged, low-growing, and fast-spreading, making marvelous additions to rock gardens and other challenging settings.

Still, others grow quite tall and exhibit isolated growth patterns, making them ideal as specimen plants in a cactus garden or centrally located planter.

A mini cactus garden is a good way to display several different varieties of Mammillaria indoors!

When grown in pots, Mammillaria Cactus makes a wonderful decorative succulent in a balcony or patio.

This video shows many of the more rugged varieties of the genus Mammillaria in their natural habitat, where the cactus grows, and could inspire some great ideas for using Mammillaria in your own desert landscape.

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