Botanical Name: Acanthocereus tetragonus
Common Name(s): Fairy Castle Cactus, Triangle Cactus, Barbed-wire Cactus, Night-blooming Cereus

The Fairy Castle Cactus is a whimsical, columnar cactus known for its upright, castle-like shape that resembles miniature spires or towers, hence the name “Fairy Castle.” Native to the southern United States, Mexico, Central America, and the Caribbean, this fast-growing cactus is often grown as a decorative indoor plant or in outdoor desert gardens. Its unique architecture and easy care make it a popular choice among succulent enthusiasts and beginners alike.

This cactus typically features vertical green stems with multiple ridges (usually three to five), giving it a distinct triangular or square cross-section. Each ridge is lined with small clusters of spines, though they are generally less aggressive than those of other cacti. When grown indoors or in containers, the Fairy Castle Cactus can reach up to 2 to 4 feet tall, while in its natural outdoor habitat, it may grow even taller. Mature specimens can occasionally produce large, white, night-blooming flowers, although blooming is rare indoors.

The Fairy Castle Cactus thrives in full sun and bright, indirect light, making it ideal for sunny windowsills, patios, or outdoor xeriscaping. It’s highly drought-tolerant, storing water in its thick, upright stems, and only needs occasional watering, typically once the soil has completely dried out. Overwatering is a common issue, so it’s important to err on the side of dryness to prevent root rot.

This cactus prefers a well-draining soil mix, such as a cactus or succulent blend. You can improve drainage by adding sand, gravel, or perlite to standard potting soil. A pot with drainage holes is essential to keep excess moisture from damaging the roots. During the growing season (spring and summer), it can benefit from a diluted cactus fertilizer once a month to support healthy growth.

Note: The Fairy Castle Cactus is generally considered non-toxic to pets and humans, but it does have small spines that can cause irritation if touched or ingested. Handle with care and place the plant in a location where it won’t be disturbed.