DIY Gardening: Caring for Fairy Castle Cacti

Experts can’t agree on the scientific names of this cactus. Is it Acanthocereus tetragonus, or Cereus hildmannianus? Is its subspecies uruguayanus, or monstrose? Most people simply prefer its whimsical common name: Fairy Castle cactus. Bright green ‘spires’ and ‘turrets’ rise up from the plant’s base and grow out of each other. Each turret is lined with straw-like spines that you can touch. Flowers are a rare reward, and Fairy castle cacti only bloom after years of quality care.

Fortunately, Fairy Castle cacti are easy to care for. It is one of the most commonly sold indoor cacti because of its popularity among beginners. You can find them at any garden center, online, or even your local grocery store. Fairy castles are native to Brazil and love full sunlight, so set it in a window where it gets early morning sun and is perhaps shaded in the afternoon. Rotate the pot every few months to keep the cactus from growing crookedly toward the light.

All cacti are succulents, meaning they swell and store water in their tissue. They are used to downpours followed my long dry spells. Soak a Fairy Castle’s soil and let it completely dry before watering again, about one or two months. Over-watering is the easiest way to damage a cactus. To aid drainage and prevent rot, plant it in a large, unglazed clay plot with a tray. Use a 50/50 mixture of potting soil and sand to mimic its natural environment.

Fairy Castles are often sold with bright straw pink or yellow flowers hot-glued to its spires to add color. Many growers prefer to gently remove the fake flowers, or allow them to fall off as the cactus grows. A more natural way to spruce up a Fairy Castle is to decorate its pot. Unglazed clay is ripe with possibilities.

Although Fairy Castles can grow quickly in the beginning–a two-inch cutting can turn into a mature, foot-tall plant with dozens of spires in just one year–their usual growth rate is slow. Pay attention to oddities that form, and check to see if the symptoms match any cactus maladies. One symptom that looks alarming but is actually part of a cactus’s natural aging process is corking. The base of the oldest stems will turn brown and woody, providing stability for the growing plant. After decades, it can have hundreds of spires and reach six feet in height. At that point it will be more like a fairy palace than a fairy castle! Don’t let its maximum height frighten you away. A Fairy Castle will certainly be a shapely, admirable plant for over a decade.