Fairy Castle Cactus (Full Grow & Care Guide)

The fairy castle cactus (Acanthocereus tetragonus) is a slow grower with a classic columnar shape and a great addition to your garden or your succulent collection. Also known as the night-blooming cereus, triangle cactus, and barbed-wire cactus, it gets its whimsical name from its vertical stems with different heights that look like spires and turrets.

The fairy castle cactus is actually a succulent that grows naturally in southern North America, Central America, northern South America, and the Caribbean. In the wild, its five-sided spines can grow (slowly) up to 6 feet tall. The bright green spines turn to brown and harden as they age, infrequently producing large white-yellow flowers.

If you are a beginner in gardening and looking for an easy-to-grow cactus, this is going to be your dream cactus. In the following parts, we will tell you how to take care of fairy castle cactus, how to propagate it, and how to deal with its most common problems.

How to Take Care of Fairy Castle Cactus?

As we said, this is a low-maintenance plant without inconvenient requirements, which even inexperienced gardeners can grow without trouble.

In this section you will see how to take care of fairy castle cactus, keeping it happy and healthy.

How Much Light Does the Night-Blooming Cereus Need?

When growing the fairy castle cactus indoors, remember that this is a full-sun plant (although it survives in partial shade too). So make sure to place it in a spot with lots of sunlight. If this plant does not receive the light it needs, its vibrant green color will fade while the columns deform.

How Often to Water Fairy Castle Cactus?

Before watering your cactus, let the cactus potting soil dry out and then water well. This method protects your plant from overwatering. Sitting in soggy soil not only causes root rot but also attracts mealybugs. And the result would be the fairy castle cactus drooping or even perishing completely.

What Is the Right Temperature for the Triangle Cactus?

If you know how often to water fairy castle cactus, your plant will be able to handle hot weather. However, you still need to protect the sensitive stem from frost and temperature below 32 degrees Fahrenheit. So if you are growing acanthocereus tetragonus outdoors, bring it inside during the cold months.

Pay attention to where you put this plant when growing indoors. Since cold drafts or air conditioning can lead to some fairy castle cactus problems.

What Is the Right Pot and Soil for Triangle Cactus?

Similar to other succulents, this plant also prefers well-draining soil. You and use cacti potting mixes available at stores, or prepare it at home with large percentages of gravel, bark, sand, or perlite to ensure proper drainage.

And for the fairy castle cactus container, we recommend unglazed pots with drainage holes. These pots absorb excess water and allow it to evaporate. When the plant has outgrown the pot (which is roughly every other year), repot it and also change its soil.

How to Encourage Fairy Castle Cactus Flower?

In general, cacti need perfect growing conditions to bloom. The fairy castle cactus flower is showy and white and only open at night like other members of the Cereus family (hence the name night-blooming cereus). These rare blooms usually do not appear until the plant has ten years or older.

So when buying this plant, if you saw a barbed-wire cactus with a flower, examine it closely, cause it is probably fake.

To be able to enjoy a fairy castle cactus flower, it is a good idea to use fertilizer while proving all the other needs for this plant. In warm months, add plant food to the soil or water to encourage growth. Don’t fertilize in cold months when the plant is dormant. And in the spring, fertilize with a cactus fertilizer.

Fairy Castle Cactus Problems

Common fairy castle cactus problems include mealybugs, scale, spider mites, fungus gnats, and centipedes (in some areas). Let us see what each change in the plant’s appearance tells you about its problem:

Fairy Castle Cactus Drooping

Overwatering and wet roots are the main cause of the fairy castle cactus drooping. As mentioned above, this magical cactus needs a lot of light and well-draining soil. Also, only water when the soil is dried out completely.

Fairy Castle Cactus Turning Yellow (and then Brown)

If you find yourself googling for “why is my fairy castle cactus turning brown?” we have bad news. Fairy castle cactus turning yellow and brown means that your cactus is rotting. And the reason might be fungus, disease, or overwatering. If the soil is always wet, a yellow shade will start to develop on the plant.

Fairy Castle Cactus Propagation

Know that you know how to take care of fairy castle cactus and avoid fairy castle cactus problems, it is time to know how to propagate it. Similar to its growing requirements, propagating this plant is not challenging as well.

For a successful fairy castle cactus propagation, simply follow these instructions:

1. Remove a branch at the base with a sterile knife or razor. Make sure to sterilize your cutting tool so that the cactus does not develop an infection.
2. Let the cut end dry out and harden for a few days. This is to encourage the new cactus to form roots faster.
3. Prepare an unglazed pot with drainage holes and fill it with a suitable potting mix.
4. Keep in a warm environment and do not overwater. When the root system form completely, you can treat it as a mature plant.

Happy gardening!