How To Grow and Care for The Thimble Cactus (Mammillaria Gracilis)

Just like any other succulent plant, the Thimble Cactus also has its preferred growth conditions to thrive and survive.

First make sure that watering, soil, lighting, and temperature are all correct. Then learn about fertilizing, propagating, and maintaining, and you’ve aced it! Thimble Cactus is perfect for beginners in succulent gardening. It’s easy to handle and doesn’t prick compared to other cactus varieties. Grow one and see!

Light Exposure

A Thimble Cactus needs to be exposed to bright sunlight. Otherwise, it will stretch and become leggy when it is not receiving enough light. Normally, a Thimble Cactus requires 4-6 hours of sunlight every day to grow and thrive.

Some succulent enthusiasts observed that young Thimble Cactus need a little less amount of sunlight a day, preferably only four hours of bright sunlight a day.

As it matures, you can increase its exposure to sunlight, ideally a total of six hours a day. Place your plant near the window for it to receive direct sunlight.

There are instances where a Thimble Cactus requires less or more sunlight than the ideal light condition mentioned above.

As the owner, you must carefully study your Thimble Cactus to ensure if it adjusts well to the daily light exposure you have set for it.

Lastly, a change in color to yellow or orange indicates too much exposure to light. In this case, move your Thimble Cactus to a shady area.


Cacti are known for their tolerance to high temperatures. Similarly, a Thimble Cactus can withstand hot temperatures, but intense heat is not good for it.

The ideal temperature for Thimble Cactus is between 70 °F to 80 °F (21 °C to 27 °C).

As for cold temperatures, it can tolerate light frost and short-term cold weather but it cannot thrive in long cold seasons.

It can adapt in temperatures down to 32  °F (0 °C) and slightly lower but it can no longer survive in temperatures that drop between 25 °F to 30 °F (-3.9 °C to -1.1 °C).

If you live in a country with a cold climate, place your Thimble Cactus indoor to keep it warm or put it in a greenhouse.

Cold periods are not necessarily harmful to your Thimble Cactus. As a matter of fact, it needs to experience cool temperatures at the end of the summer because low temperatures and reduced watering can prompt blooming.


Thimble Cactus or Mammillaria gracilis is native to the hot deserts in Mexico. It is used in hot and dry climates but not in overly humid conditions.

Room temperature is ideal for this cactus.

If you feel like your house is too hot and stuffy, especially in the summer, you can open the windows so that your Thimble Cactus would get ventilated.

Using a dehumidifier can also help in maintaining the right amount of humidity in your house or room.


Succulents can conserve water through their thick and fleshy parts. For this reason, a Thimble Cactus does not need much watering.

The ideal frequency of watering in Thimble Cactus is quite tricky as it depends on many factors, particularly light intensity.

In watering this succulent, use the soak-and-dry method. This means that you must completely dry out the plant before watering again.

If this is too tiring for you, here is a quick guide in watering Thimble Cactus:

If your outdoor Thimble Cactus gets adequate full exposure to the sun every day, you can water it once or twice a week. Indoor Thimble Cactus most likely requires a little less watering in which once a week would suffice.

Because of the cold weather, Thimble Cactus can be watered only once a month or less in the winter season. Make sure to use lukewarm water during this season.

Your pots should have drainage holes at the base to avoid clogging that will result in the rotting of the roots. Also, place a saucer plate under the pot to hold the water as it flows out.


Thimble Cactus prefers well-drained soil because it retains water long enough for the cactus to absorb and this soil dries out adequately between watering.

This enables the roots to capture oxygen and prevents them from rotting due to excessive moisture.

The most common soil component used in potting Thimble Cactus is composed of 50% potting soil and 50% perlite.

It grows best in fast-draining soil with a pH of 6.1 to 6.5. You can buy this mixture online or you can make your own mixture using 50% organic and 50% nonorganic mix.

Another effective option is the use of soilless medium such as grit to provide good drainage for your Thimble Cactus.


Since Thimble Cactus is a small cactus, you do not need a big pot for it. Instead, plant it in a small pot.

You do not have to dig deep in planting it because its roots do not grow deep.

Repotting can be done once every two to three years, particularly after its hibernation in spring.

If in the process of repotting you see a damaged root, remove it before replanting.


Thimble Cactus only needs fertilizer during its growing season. You do not need to fertilize its soil in the winter because it is dormant during this period.

You can either choose from chemical or natural organic fertilizer. However, most succulent enthusiasts prefer the latter to protect the environment.

Apply fertilizer once a month; planting Thimble Cactus for the first time is the best opportunity to start fertilizing the soil.

How To Propagate Thimble Cactus

Thimble Cactus is easy and simple to propagate. Its propagation is via offsets, the tiny succulents that grow around the base of the mother plant.

You just need to remove the offsets from the base and let it dry for a few days. The dried offsets will instantly grow once placed in a pot with a well-drained soil.

Common Problems in Thimble Cactus and How To Fix Them

Three of the most common issues associated with Thimble Cactus are bacterial/fungal disease, pest control, and bleaching.

• Bacterial/fungal disease 

This is most often caused by excessive watering and very humid air.

Too much moisture in the soil can rot and destroy the roots. In this case, transfer the Thimble Cactus into a different pot and remove rotten roots.

• Pests

Common cactus pests are spider mites, fungus gnats, and plant scale bugs.

It is difficult to spot these pests as they are too small to notice. However, you can use a diluted rubbing alcohol solution to remove them.

• Bleaching

Bleaching is when your cactus loses its green color and turns yellow or orange.

This indicates poor and insufficient exposure to sunlight, hence, all you need to do is maintain the daily light exposure of your Thimble Cactus for four to five hours.


When properly taken care of, a Thimble Cactus can grow healthily in its forest green color and white starry spines.  It can grow into beautiful clusters from the offset sprouts at the bottom of it.

Thimble Cactus is normally small, averaging to 7.5 cm to 12.5 cm tall and 7.5 cm to 10 cm wide. It is cylindrical and looks very much like its name–a thimble. In late winter, tiny creamy yellow flowers bloom from it.

In general, a Thimble Cactus grows in a bright, sunlit area with low humidity. It also adjusts well in smaller pots with the right kind of fertilizer, preferably a natural organic fertilizer.

Pests and bacterial/fungal diseases are common in Thimble Cactus, therefore, careful inspection of the succulent from time to time is necessary.

Final Thoughts

Thimble Cactus is very easy to take care of. Just like its native ancestors in the wild, it can grow in a wide range of temperatures and does not need much attention.

In addition to this, Thimble Cactus is also very easy to propagate.

All the other factors affecting the growth of Thimble Cactus are very minimal and simple to follow.

The most important of all factors is the light exposure and the soil. Remember that a

Thimble Cactus does not need much watering; all you need to do is provide it with four to six hours of sunlight every day.

The soil needs to be well-drained as cacti love this type of soil. As for the fertilizer, it is better to choose an eco-friendly one that will not contribute to the existing air pollution.

Thimble Cactus is a great addition to your cactus collection. It is the perfect cactus for beginners in succulent gardening because it is easy to handle and does not prick compared to other cactus varieties.

Jenny Marie
Tribal Writer

Edited By
Patricia Godwin

Patricia Godwin

Patricia has many years of experience as a content writer on various subjects, but her first love is gardening. She’s never met a plant she didn’t like and, consequently, she writes about every type of plant you can think of. Once an avid gardener with a herb garden, a succulent rockery, and a rose garden – to mention a few. Nowadays, she’s constantly on the move searching for interesting plants to bring to your attention; and explain to you all the details you need to grow, care and maintain these plants.

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