Fairy Castle Cactus – How to Care for this Breathtaking Plant

Today I present to you a dwarf and very particular variety of Acanthocereus, a variety which branches out from an early age, thus giving it a bushy and full appearance. The Acanthocereus tetragonus cv. ‘Fairytale castle’ or Fairy Castle cactus!

Cereus, members of the Cactaceae family, are tough candlestick or candle-shaped, sometimes even candelabra-shaped cacti that have been fairly common in our homes for many reasons for decades. Their ease of cultivation, their very low water requirements and their original appearance have made them a flagship plant in our interiors as well as in Mediterranean or dry tropical gardens.

As its name suggests, the Fairy Castle cactus is a real fairy castle! Its stems, columnar and branching out from the base are really reminiscent of a fairy tale castle, straight out of a child’s overflowing imagination or the pen of an author.

fairy castle
fairy castle cactus in pot 1
Branched stems of Acanthocereus tetragonus cv. ‘Fairytale castle’

You can immediately distinguish it in the photos – it is its stems with many compact and dense ramifications that make it an interesting and unique cactus. Over time, they will develop in height and width, leaving us to imagine a magical fortress in full construction.

The true self of this plant is controversial and some suggest that it may be a form of Cereus hildmannianus. Whichever scientific name is correct, the plant is a delightful cactus.

fairy castle cactus outside

Moreover, unlike the Cereus hildmannianus, it is surprising to notice that the thorns present on the ribs of this cultivar, are almost non-prickly. A significant additional advantage?

How to Care for Fairy Castle Cactus


For our Fairy Castle cactus, we will choose a location exposed to full light or at least very bright. Some cacti can still dry out under the effects of the scorching rays of direct sunlight, so I advise you to avoid full sun for this type of cactus.

The Fairy Castle cactus always leans in the direction from which most of the light falls. So rotate the pot from time to time so that the cactus grows straight up.


In spring and summer, water the cactus every two to three weeks depending on the temperature and humidity of the air and the substrate. In winter, watering is not recommended if temperatures drop below 12 to 15 degrees Celsius. The cactus then enters into winter rest.

However, in the event that temperatures do not drop below 15 degrees, it is advisable to reduce the frequency of watering at a rate of every four to five weeks following significant changes in light.


Fertilizing is not necessary for this cultivar of Acanthocereus. However, during the right season, you can give it a very light dose of liquid fertilizer rich in potassium and minerals (such as tomato fertilizer for example), to be diluted in the irrigation water, every two or three waterings.

fairy castle cactus red 1


In the spring, repotting can be done, which may be necessary if the plant has grown. To do this, you will use a mixture of well-drained soil composed of two-thirds of soil and one-third of draining material such as perlite or small gravel.

Note that some ready-made cactus potting mixes are available. Make sure to use a container with the same diameter or slightly larger than the previous one. Indeed, cacti only consume very little water, a container that is too large will inevitably generate an excess of water which could cause the roots of the plant to rot.

What Diseases and Pests to Watch Out For

The Fairy Castle cactus is very susceptible to diseases and pests. Rotting and fungal attack occur especially when it is wet.

Watch out for pests and always treat pests immediately. Chemical agents have little effect. Often times, you will get better results with natural predators. Common pests are:

  • Spider mites
  • Mealybug
  • Root mealybug

If you’re caring for the Fairy Castle cactus outside in the summer, check the soil for larvae of black weevils and other pests.

How to Care for Fairy Castle Cactus in Winter

Fairy Castle cacti are not hardy and cannot tolerate temperatures below five degrees. In winter, you should give the plant a break and place it cool but very bright at six to eight degrees. Cut down on watering to once a month.