Fairy Castle Cactus Care (Acanthocereus tetragonus)

Fairy castle cactus

Last updated on August 29th, 2022 at 09:37 pm

Fairy castle cactus, also known as Acanthocereus tetragonus, cereus tetragonus, fairytale castle cactus, or just fairytale cactus, is a small, low-growing species that reaches heights of only about four to six inches. They have flat, round stems and dark green spines on the end.

It does not do well in hot climates during the summer months because it has no water storage mechanism or protection from high heat (meaning it will die) in direct sunlight. If you see a Fairy Castle Cactus with brown edges, it is dehydrated.

The only way to water fairytale castle cactus is either by misting it regularly or soaking the soil in its pot every couple of weeks and allowing time for the excess moisture to drain away before watering again. In order to keep your fairy castle cactus alive, you need to make sure it has a well-draining soil mixture and some humidity in the air.

Heights: four to six inches long

Spines: dark green on ends

Drought tolerant? No (dies if exposed to direct sunlight during summer months)

Watering method: mist or soak

Soil mixture: well-draining

Humidity requirement: some humidity in the air.

Fairy castle cactus propagation

Fairy castle cactus

Propagation of this species is done with cuttings. Use a sharp blade to make clean cuts on the side of the cactus where there are no spines, and allow several days for it to dry out before planting in potting soil or perlite. The bottom should be planted at least an inch below ground so that water does not seep in.

A simple way to propagate cereus tetragonus is by separating a potted plant into two or three sections in late summer before it has started to produce new pads. The pieces can be planted about six inches apart and watered regularly. It should take several years for the cactus to grow back but if you do not have patience, cuttings can be taken.

The best time to propagate cacti is after the summer rainy season (June-August) when the plants are starting to slow down and enter dormancy. When planting, try to find a place that’s out of direct sunlight but still receives plenty of light. It will need at least six hours of sun a day.

Fairy castle cactus care information

Fairy castle cactus

Fairy castle cactus care is easy, you just need to follow some basic tips as highlighted below:

Light requirements

Fairy Castle Cactus prefers bright, indirect light. Too much direct sunlight will cause the plant to drop its leaves and turn yellow or brown. If you notice your cacti doing this, move them away from any windows that might be letting in too much sunlight. They also need lots of air circulation so make sure they are not in a drafty spot.

Schlumbergera × buckleyi: The True Christmas Cactus

Fairy Castle Cactus plants do really well under grow lights, so if you don’t have any windows near your cactus that are lit enough for it to get the right amount of light, try placing them anywhere else where there is adequate indirect light and lots of air circulation.

If Fairy Castle Cactus is getting enough light, but it’s still dropping leaves or turning yellow, then you may be watering too much.

Soil/potting mix

When potting your cacti, make sure the soil is very well-drained. Cactus prefers a sandy, clay-free mix that drains water quickly and doesn’t stay wet for long periods of time. Gardeners often use small pebbles or crushed glass on top to help keep it dry while still retaining some moisture close to the roots.

It is not necessary to water Fairy Castle Cactus every day or even twice a week. The most important thing you can do for your plants, in general, is to pay attention and make adjustments as needed.

Fairy castle prefers cacti soil mix that does not contain too much sand, so it’s best to use a potting mix or soil that is made specifically for cacti.

Fairytale castle cactus fertilizer

Fairy castle cactus does not need to be fertilized every time the soil is watered. In fact, it’s better to water them less often and use a fertilizer that doesn’t contain too much nitrogen.

Do you want your plants to grow bigger? Then you may wish to fertilize with a product like Miracle Grow twice per year during the spring and summer.

When fertilizing, you should water your plants first before adding fertilizer. This will help to prevent burning the roots due to salt build-up from too much fertilizer in the soil’s moisture.


Fairy Castle Cactus prefer watering as needed, or about once per week. The best time of day for watering is usually during the late evening when it’s cooler out so that evaporation doesn’t lead to overwatering.

When you water your plants, make sure there are no standing puddles, and then wait a few minutes before watering again.

If your Fairy Castle Cactus is turning yellow or dropping leaves, then you may be overwatering them due to too much water retention in the soil mix. You should try sandy cacti soil with more drainage so that there isn’t as much standing moisture and they don’t need to be watered nearly as often.

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Fairytale cactus temperature

Fairy Castle Cactus prefer warm temperatures. They can tolerate some cooler temps, but not below 55 degrees Fahrenheit or 13 Celsius.

The ideal temperature range for Fairy Gardeners is 65-75 degrees Farenheit (18-24 Celsius) with a nighttime dipping down to about 60°F (-16°C).

Cereus tetragonus humidity

Fairy castle cactus

Fairy Castle Cacti prefer a humidity range of 40-50%. If the relative humidity is too high, it can be difficult for the plant to absorb water and they will drop their leaves or turn yellow.

Growth rate

Fairy Castle Cactus can grow slowly over time, but they also have the ability to put on a lot of growth in one season.

If you want your Fairy Castle plants to start producing significant new growth, then shift them into an area that is brighter and has more air circulation. This will help them produce healthy leaves and stems with less risk of rotting or pests.

If fairy castle cactus is still not producing new growth, then you may want to fertilize them with a product that is lower in nitrogen and water less often so there isn’t as much standing moisture. You can also try increasing their exposure to sunlight by moving the pot into an area where they will receive more light.

Sometimes, Fairy Castle Cactus will grow new stems or create offsets to send out multiple clumps. This is a natural process that helps them spread and produce more cacti! It’s best not to disturb the roots of these plants as they may be healing from transplanting stresses.

Repotting Acanthocereus tetragonus

Fairy Castle Cactus should not be repotted more than once every two to three years.

The best time of day for potting is usually during the late evening when it’s cooler out so that evaporation doesn’t lead to over-watering and increased plant stress, which could then slow or stop new growth.

When potting your plants, make sure they have a drainage hole in the bottom of the pot, and then fill up with soil mix that is equal parts peat moss, vermiculite, or perlite.

If you’re wondering how to repot Fairy Castle Cacti without damaging their roots, it’s best not to disturb them too much when repotting. You might want to turn the pot on its side and carefully remove it from the old soil – this will help reduce damage to roots if they are not fully healed or could be damaged by moving them too much while repotting.

Echinocereus triglochidiatus (Claret Cup Cactus)

If you’re going to re-pot the fairy castle plant, make sure that you keep the pot in an area with a consistent temperature range of 65-75 degrees Fahrenheit (18-24 Celsius) and that it’s on the dryer side to reduce plant stress.


Fairy Castle Cactus can look great if they are pruned and kept to a single cluster of stems.

When you’re ready, use only clean tools with sharp blades for the best results – we recommend using shears that have been disinfected before each cutting session.

To make your Fairy Garden as full as possible, try removing some of the branches that are growing upward and directing them to grow downward. You can also remove some of the bottom stems by cutting just above a node – this will encourage new growth from other nodes on the stem!

It’s also important not to let your plants get too tall so it becomes difficult for them to move water up through their stems, causing them to droop.

If you want a smaller Fairy Castle Cactus, then prune off the top of your plant until it’s just two or three branches tall – this will encourage new growth from below!

When cutting stems, make sure that you’re holding them so they are at an angle and not cut straight through because this could cause plant stress.

When cutting off the tip of your plant, make sure to leave a few nodes at the base so it can continue to grow and produce new growth! You should also trim off any stems that are longer than four inches in length – this will encourage healthy root development below as well as help keep the water from pooling too much on the top of the soil.

Hardiness zone

Fairy Castle Cacti are hardy to zones USDA-hardiness zone (which ranges from) USDA Zone 11, 12, and 13.

In colder climates, they will need more care to survive the winter months – we recommend moving them into a warmer area during this time of the year or bringing them inside so they have access to a consistent temperature year-round.

In warmer climates, they can be planted outside all year long as long as there is sufficient shade to protect them from the summer heat and plenty of sun for them during the winter months!

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Fairy Castle Cacti are NOT toxic to pets or humans, but please note that they do produce a white sap when you cut them.

If the sap gets on your skin, it will also be inedible and can cause irritation if not washed off immediately with soap and water!

Acanthocereus tetragonus flower

Fairy castle cactus

The Fairy Castle Cactus produces small flowers which are also edible – we recommend you remove the petals before eating them, or just leave them for your Fairy friends to enjoy!

Pests and diseases

There are few pests and diseases that can affect the fairy castle cactus plant since they’re succulent.

The most common problem is rot or mold because of the high water content in this type of plant – make sure to keep them well-watered but not sitting in any standing water!

If you start seeing yellowing leaves, this could be a sign of root rot. We recommend that you remove and discard these leaves, then water the plant generously to avoid further damage – if there’s any standing water in the pot or tray, it should also be removed as well!

The Fairy Castle Cactus is not prone to insect infestation but can sometimes get aphids – luckily, they are easy to remove with a spray of water or by using insecticidal soap.

You may experience some other pests, such as mealybug and scale insects – but these can be easily removed just by wiping them off the plant with rubbing alcohol.

Additional facts on fairy castle cactus

Fairy castle cactus are great plants that look like miniature castles in your garden!

They are great for use in Fairy Gardens and require little care. They even help clean the air by removing toxins, such as formaldehyde and benzene, from indoor environments.

If you’re wondering how to grow a Fairy Castle Cactus indoors or outdoors, make sure that they have access to plenty of light (indoors) or that you plant them in the ground or a pot.

Fairytale cactus needs access to sunlight for at least six hours per day, so make sure to place your plants where they’ll get full sun – lookout for overhanging trees and structures!