The fishbone cactus, known botanically as Disocactus anguliger or sometimes Epiphyllum anguliger, is a houseplant treasured for its unique, flattened stems that zigzag in a pattern reminiscent of a fish skeleton. Unlike the familiar desert cacti, this species is a jungle cactus, naturally growing as an epiphyte on the branches of trees in the rainforests of Mexico. This distinction means its care requirements differ significantly from its arid-loving relatives, demanding a balance of moisture and excellent drainage. Understanding its tropical origin is the first step toward successfully cultivating this striking, trailing plant indoors.
Ideal Environmental Conditions
The fishbone cactus thrives in conditions that mimic the jungle understory, requiring bright but diffused light rather than intense, direct sun. A location near an east or north-facing window is often ideal, providing several hours of light without the harsh rays that can scorch its delicate stems. Direct, midday sunlight should be avoided, as it can scorch the stems, causing them to yellow or develop a bleached, pale appearance.
Optimal temperatures generally range from 60°F to 78°F throughout the year. The plant is intolerant of cold drafts and should be kept away from exterior doors or air conditioning vents, though it can tolerate a brief drop to around 50°F during a winter rest period. High ambient moisture is beneficial, with humidity levels of 50% to 60% supporting healthy growth. Placing the pot on a pebble tray or using a room humidifier can help maintain the necessary moisture in dry interior environments.
Watering Techniques and Substrate Selection
Successful care for this epiphytic cactus hinges on balancing its need for moisture with its requirement for rapid drainage. The correct watering method is a “soak and dry” approach, where the plant is thoroughly watered until it drains from the bottom, and then the top two to three inches of the potting mix are allowed to dry completely before watering again. Overwatering is a common cause of failure, as its roots cannot tolerate being perpetually saturated, which leads to root rot.
Watering frequency should increase during the active growing period of spring and summer and reduce substantially in the cooler, dormant months. During the winter, the plant may only need water once every three to four weeks, depending on the environment. Use room-temperature water, and allow tap water to sit for 24 hours to help chemicals like chlorine dissipate.
Because the fishbone cactus naturally grows on tree bark, it demands a potting mix that is highly airy, chunky, and fast-draining to prevent compaction. A suitable substrate should contain significant organic matter and large particles. Use a mix of commercial cactus soil blended with materials like orchid bark, perlite, or pumice to ensure excellent aeration for the roots.
Encouraging Growth and Propagation
To support vigorous growth, the fishbone cactus benefits from regular feeding during its active period. A balanced, diluted houseplant fertilizer or one specifically formulated for cacti can be applied monthly throughout the spring and summer. Some growers switch to a fertilizer higher in potassium during the summer to encourage the formation of its spectacular night-blooming flowers. Fertilization should be suspended entirely during the fall and winter when the plant’s growth naturally slows down.
The plant enjoys being somewhat root-bound, so repotting is only necessary every two to three years or when the roots completely fill the container. When repotting, select a container only one size larger than the previous one and use a fresh batch of the recommended chunky, well-draining epiphytic mix.
Propagation
To take a cutting, a healthy stem segment about four to six inches long should be removed with a clean, sharp tool. The cutting must then be placed in a cool, dry location for at least 24 hours to allow the cut surface to dry out and form a protective scab, known as a callus. Once calloused, the cutting can be planted directly into a small pot of the same airy potting mix, with the medium kept lightly moist until new roots and growth establish.
Addressing Common Care Difficulties
A common sign of distress is limp or shriveled stems, which typically indicates a severe lack of water, causing the plant to draw moisture from its own tissue. Conversely, brown, mushy stems are usually a sign of root rot, which is a consequence of overwatering and poor drainage. Correcting the watering schedule and ensuring the soil is not compacted are the primary solutions for both issues.
Pests
Pests like mealybugs and scale insects may occasionally infest the plant, often congregating in the crevices of the stem segments. These sap-sucking insects can be treated by manually wiping them off with a cotton swab dipped in rubbing alcohol or by applying a solution of insecticidal soap or neem oil to the affected areas.
Failure to Bloom
Failure to bloom is often related to a lack of winter rest. The plant requires a period of cooler temperatures, ideally between 50°F and 57°F, and reduced watering during the winter months to set flower buds.