Fairy Castle Cactus – How To Grow, Care And Propagate A Magical Miniature Cactus!


Fairy Castle Cactus, a miniature cultivar of Acanthocereus tetragonus (a popular species of cacti native to North and Central America), features many cylindrical stems which, as the plant grows, join together vertically, recalling the towers of a fairy castle. Each stem has five sides covered in little white spines growing along the ribs. So, you might ask, how big does a Fairy Castle Cactus actually get? Well, even though it’s a very slow-growing plant, it can reach up to 6 feet (almost 2 meters) tall!

Fairy Castle Cactus rarely blooms, but when it gets to its mature stage (sometimes after a decade or more!), can produce white or yellow large flowers. This cactus is very trendy and you can easily find it online, at your local garden center, and even at the grocery store! If you get yours at your local store, it will probably come with bright pink or yellow fake flowers glued to the top of the stems, and you may wonder why.

It’s just a commercial strategy to make the cactus look more appealing to customers, but, once you get home with your new thorny friend, make sure to carefully remove the fake flowers without damaging the poor plant. If you want to find out more about how to care for Fairy Castle Cactus, keep reading this informative article!

Featured Image Credit: @thesomethinggreen

How To Care For Fairy Castle Cactus

Fairy Castle Cactus is an excellent choice for beginners. It doesn’t require any special care and can survive in many environmental and growing conditions. It can be grown both indoors and outdoors. In any case, keep in mind that you will need to provide your plant with proper growing conditions to make it thrive well.

Frost Tolerance

Fairy Castle Cactus is semi-hardy, so if you live in a zone that gets colder than 30° F (-1.1° C), you should grow your plant in a container that can be brought indoors.

To say more, Fairy Castle Cactus is hardy to USDA zone 10 to 11 only so, depending on where you live, you will need to grow this plant indoors and move it outside just for the warmer months of the year. This cactus is really not cold-hardy, will suffer greatly in freezing climates, and won’t be able to tolerate frost for very long. If your region gets mild winters, you may be able to leave the plant outdoors all year long and even plant it directly into the ground.

However, if you live in an area with extreme winter conditions and temperatures below 20°F (-6,7 C°), you should grow your cactus in pots or containers and keep it indoors or in a greenhouse to protect it from freezing temperatures. If you have to leave your plant outdoors during winter, make sure you provide protection from frost by using frost cloths.

Light Requirements – How Much Sun Does A Fairy Cactus Need?

You just bought your new spiky friend and now you are wondering ‘How much sun does a fairy cactus need?‘ Well, if grown outdoors as part of a cactus or succulent garden, your Fairy Castle Cactus should be planted in an area that gets at least 6 hours of morning sunlight. However, during extreme heat or heat waves, it’s a good idea to place a sunshade over the cactus to protect it from sunburn. If grown indoors, make sure to provide your plant with plenty of bright light by placing the pot in a sunny spot such as near a southern-facing window. If you lack sunlight, you may use grow lights, but natural light is always preferable.

Water Requirements – How Often To Water Fairy Castle Cactus?

As far as watering requirements, always remember that Fairy Castle Cactus is drought-resistant, and overwatering it may lead to waterlogging and then root rot. So, how often to water Fairy Castle Cactus?

If you keep your cactus outdoors and you get regular rainfall in the area where you live, you can forget about watering!  Otherwise, water every 2-3 weeks during summer and less frequently during the winter months, when the cactus goes dormant. If you grow your cactus in pots or containers, I suggest you follow the ‘soak and dry’ method: water the soil until it is completely soaked and wait until it’s totally dried out before watering again (this may depend on your location and container). It’s also important to keep Fairy Castle Cactus in well-draining soil in a pot with drainage holes to avoid root rot.

Pot And Soil Requirements

If you plan to grow your Fairy Castle Cactus in a pot, you should choose a terracotta or clay one with drainage holes to reduce the risk of overwatering and consequent root rot. Terracotta or clay pots provide a healthy environment for most plants. The porosity of clay allows air and moisture to penetrate the sides of the pot. That being said, terracotta pots release moisture faster when it’s hot outside, which means you’ll need to water the plants more frequently to prevent soil from drying out.

For best-growing results, use a fast-draining cactus mix that allows for stronger root growth. For extra drainage, you can add 70% to 80% mineral grit such as coarse sand, pumice, or perlite.

As far as fertilizing your Fairy Castle Cactus, if you’ve just repotted it in fresh soil, fertilization may not be necessary since the soil still has plenty of nutrients in it. However, if you do need to add some nutrients to the soil, it is best to apply organic fertilizer, specifically designed for cacti, at half-strength during the spring-summer season when the plant is actively growing. Do not fertilize during the winter months when the plant is dormant.

Repotting Tips – How And When To Repot Fairy Castle Cactus

When your Fairy Castle Cactus has outgrown a small pot, transplanting is necessary and beneficial to the well-being of the whole plant, preferably during the warm season. Start by gently removing the whole plant from the pot. Then remove the old soil from the roots and look for any signs of pests or decay. Don’t be afraid to prune roots too – it’s helpful and encourages new growth.

Place the plant in a larger pot and fill it up with potting soil, spreading the roots out as you repot. Leave the soil to dry for a week or more, then start to water lightly to reduce the risk of overwatering with consequent root rot.

Pests Affecting Fairy Castle Cactus


Mealybugs are common pests that attack the roots, body, and spines of your cactus. Getting rid of them can be quite challenging since these pests have a wooly protective cover making them resistant to common pesticides.

They have an amazing ability to hide in the unexpected and narrowest places like between stem and leaves, nested in dried-up leaves, under pots, and tables.

They can even hide in debris around the plant and lay their eggs (up to 600) out of sight but close to the plants so when the little nymphs hatch, they don’t have far to crawl.

This is why detecting them early and isolating them is the best practice. It’s also important to keep clean not only the pots but also the whole area around them.

Solution: if you happen to find a few bugs, it’s easy to squash them with a toothpick. Next, pull out the infected leaves and thoroughly check around the plant to see if there are any bugs left.

Once you have detected and isolated the infected plant, it’s crucial to keep an eye on it for several weeks, just to make sure there aren’t any other outbreaks.

Another possible scenario occurs with a large mealybugs infestation: in this case, it’s necessary to spray the plants with a 70% rubbing alcohol or isopropyl solution with multiple applications. To completely get rid of these tiny pests it’s necessary to kill and wash off every single one.

Why Is My Fairy Castle Cactus Turning Brown?

When your cactus starts turning yellow and then brown and mushy at the top it means that is rotting, unfortunately. Cactus rot is caused by either fungus, disease, or overwatering.  If you keep the soil too wet you can see a yellow shade developing on your cactus. This is a sign of stress and the plant can’t live in such moist conditions. But just because your cactus is rotting doesn’t mean you can’t save it. What you want to do is stop watering and prune your cactus with a sterile sharp knife or pruning shears to remove the rotted part.

How To Propagate Fairy Castle Cactus

Fairy Castle Cactus can be propagated by cuttings or by seeds.  Make sure to use well-draining soil when planting the cuttings. I like to use a combination of cactus mix and perlite (1:1 solution). You can also add coarse sand to this mixture (1:1:1 solution) for added drainage.

By Cuttings

Fairy Castle Cactus can be easily propagated from cuttings. Following a few easy steps, you can successfully propagate your cactus.

  • Start by wearing a pair of rubber gloves to protect your hands from the sharp spines of your cactus. Using a clean, sharp knife cut a branch from the mother’s plant.
  • Place the cutting onto a piece of paper towel and allow it to dry out for a few days until the ‘callus’ ( a soft tissue that forms the cut leading to healing) is formed over the cut surface.
  • When the cutting is nice and dry, dip the end into the rooting hormone (optional) and stick it cut-side down into well-draining soil.
  • Keep the container in a bright spot but away from direct sunlight then slowly transfer it to a sunnier spot.
  • To avoid any risk of root rot or other infections, do not water your cuttings right away. Wait for a few days and then water sparingly, only when the soil feels dry to the touch.

By Seeds

I find this one quite a tricky method and I wouldn’t recommend it because Fairy Castle Cactus is a slow grower. But if you want to try it, go for it! All you want to do is collect the seeds of its overripen fruits. Once you have the seeds, clean them and let them dry. At this point, plant them in a well-draining soil mixture and water only when, touching the soil with your finger, it feels dry. Keep in mind that weather plays an important role to successfully propagate your Fairy Castle Cactus: if the temperatures in your area don’t drop below 32°F (0°C), you can place the seeds outdoors, otherwise, it’s best to keep them indoors under grow lights.

Is Fairy Castle Cactus Toxic To Pets?

Fairy Castle Cactus is not mentioned on the list of ASPCA toxic plants for pets. Your four-legged friend is unlikely to get too close to your cactus anyway, due to the presence of its sharp spines. However, if he does get stung, my advice is to call your veterinarian right away to avoid complications.

Final Thoughts

Hope you enjoyed reading this article on Fairy Castle Cactus (Acanthocereus tetragonus) and found it comprehensive and enlightening! If you like, feel free to leave a comment or share your knowledge on this topic in the section below.