The Whimsical Beauty of the Fairy Castle Cactus

The Fairy Castle Cactus, Acanthocereus tetragonus, is native to Central America, Mexico, the Caribbean, and the southern United States. This cactus is a slow-growing variety and is considered low maintenance. 

Acanthocereus tetragonus

Fairy Tale Cactus Appearance

The Fairy Castle Cactus grows 6 feet (2 meters) tall at maturity. The cactus earns its name from the plant’s multiple stems, of varying lengths, that resemble the turrets and spires of a castle.

The stems are five-sided and feature wooly spines on each plane. While the stems start out as bright green, they turn woody and brown with age. Fairy Tale cactus flowers often do not appear when grown indoors.

Young plants may not bloom at all with the best chance of flowers occurring on plants 10 years or older. Flowers are white or yellow and average 3 to 6 inches ( 7.6 to 15.2 cm) in length. The blooms appear at night.

Fairy Tale Cactus Light Requirements

For proper Fairy Tale cactus care, provide full sun or partial shade. At least six to eight hours of direct sunlight is recommended. If moving the plant outside, place it in full sun but watch for signs of dehydration such as color change or shrunken stems. Avoid low lighting as it causes faded color and misshapen columns. 

Water Needs

Allow the soil to dry completely between waterings for your Fairy Tale cactus. Water until it seeps through the soil and collects in the drip tray. Pour out excess water collected to avoid root rot. For proper Fairy Castle care, grow the cactus in an unglazed clay pot which allows wicking of excess soil moisture.

Temperature and Humidity

Temperature and Humidity
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The Fairy Castle cactus loves high-heat conditions. Provide temperatures between 64-79 degrees Fahrenheit (18-26 degrees Celsius) during the spring and summer growth months. For optimal Fairy Castle care, avoid temperatures below 30 degrees Fahrenheit ( -1 degrees Celsius) as the plant is not frost tolerant. Average household humidity levels are sufficient for the plant to thrive. Avoid placing the cactus near cold drafts or air conditioners. 

Soil and Fertilizer

Use a soil mixture that is well-draining such as cactus soil. Make your own soil using one part each of a peat-based potting soil, coarse sand, and perlite. For added drainage and root protection, add a 1-inch layer of fine gravel to the bottom of the plant’s pot. Feed your Fairy Castle cactus once per month with a liquid fertilizer in the spring and summer. You can also dilute the fertilizer into your watering can and provide a weak feeding at each watering. Do not fertilize the cactus during the winter as it requires dormancy.

Fairy Castle Cactus Propagation

Propagation of the Fairy Castle cactus is possible by both seeds and cuttings. Due to the plant’s slow growth rate, cuttings is the recommended procedure. If propagating by seeds, collect the seeds from dried blooms and sow them in a small pot filled with a cactus soil mix. Keep the soil moist and place the pot in a warm location. For cuttings, cut a stem using a sharp and sterile knife. Let the cutting sit until a callus forms over the cut end. Place the cut end into a pot filled with a cactus soil and keep the soil moist until roots form. Once the new cactus is established, water as you would the mother plant. 

Fairy Castle Cactus Pests and Diseases

Proper Fairy Castle cactus care will eliminate the chance of infestations. If your cactus is struggling, Mealybugs and scale are common pests for this variety. If caught early, remove the pests by wiping the plant with a cotton swab dipped in rubbing alcohol. Full-plant infestations require treatment with neem oil or an insecticidal soap. It is recommended to quarantine the plant until the infestation is resolved. 

Your Fairy Castle cactus may develop root rot if it is overwatered or the pot’s drip tray is not emptied after waterings. Remove the cactus from its pot and snip away any dark or mushy roots with a pair of sharp, sterile shears. If significant rot is present, stop the bacterial spread by repotting the plant in fresh soil. Treat the new soil by pouring a mixture of one part 3 percent hydrogen peroxide and two parts water into the dry soil. This will kill off any remaining bacteria. 

The Fairy Castle cactus has an enchanting appearance and makes a great addition to any cacti collection. The plant is sun and drought tolerant, making it a perfect plant for a sunny location both inside or outdoors. 

Fairy Castle Cactus FAQ
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Fairy Castle Cactus FAQ

What Type of Pot Should I Grow My Fairy Castle Cactus in?

While this cactus does produce several stems, like the Peanut Cactus, the stems grow upright and do not trail. A wide, clay pot is recommended to allow the stems to form without being crowded. 

Can I Grow a Fairy Castle Cactus Outdoors?

Yes, this cactus will grow outdoors in USDA zones 10 and 11. It is tolerant of full sun but do watch for signs of scorching and adjust accordingly. Bring the plant indoors once temperatures dip near freezing.

What are Other Names for the Fairy Castle Cactus?

Alternate names for the Fairy Castle cactus include the Night Blooming cereus, Triangle Cactus, and Barbed Wire Cactus

When Should I Repot My Fairy Castle Cactus?

On average, this cactus requires repotting every two years to accommodate its wide root system and sprawling growth pattern.

Can I Buy a Fairy Castle Cactus with Blooms?

It is rare to buy this plant with Fairy Castle cactus flowers already present. In fact, it has been reported that some sellers will glue fake flowers onto the cacti to increase sales. Blooms should be either white or yellow and not be dry to the touch. 

Cindy McKie
About Cindy McKie
Cindy McKie provides helpful, easy-to-follow care guides for plant lovers of all experience levels. She has written for several online gardening publications and has self-published her own guide to growing herbs under the pen name Sophia Darby. When not writing about plants, she can be found in her gardens or reading a good book.

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