The Red Cathedral Cactus is a striking houseplant known for its unique architectural form. Its upright, columnar growth and vibrant coloration make it a captivating and relatively low-maintenance addition to indoor plant collections.
Understanding Your Red Cathedral Cactus
Despite its common name, the Red Cathedral Cactus is not a true cactus but belongs to the Euphorbia genus, specifically Euphorbia trigona ‘Rubra’ or Euphorbia trigona rubra. This succulent is often called the African Milk Tree due to its milky sap. It features upright, multi-branched, columnar stems that are typically triangular in cross-section, contributing to its species name “trigona”. The stems of the ‘Rubra’ cultivar display a distinctive reddish-burgundy hue, sometimes with mottled patterns of green and purple, especially when exposed to sufficient light. Along the ridges of these stems grow small, teardrop-shaped leaves that are deciduous, meaning they will periodically shed. This plant originates from central regions of Africa, including Angola, Gabon, and Congo, where it thrives in warm, arid environments.
Essential Care for Red Cathedral Cactus
The Red Cathedral Cactus thrives with specific care tailored to its succulent nature. Providing the right conditions for light, water, soil, temperature, and feeding ensures its vibrant appearance and healthy growth.
Light Needs
The Red Cathedral Cactus prefers bright, indirect sunlight for at least four to six hours daily to maintain its rich reddish-burgundy coloration. While it can tolerate some direct morning or late afternoon sun, excessive direct sunlight, especially during the hottest parts of the day, can scorch its stems and leaves, leading to brown or red patches. Conversely, insufficient light can cause the plant to stretch or etiolate, resulting in leggy growth and a loss of its vibrant hue. If natural light is limited, supplemental grow lights can provide the necessary intensity.
Watering Schedule
A proper watering routine for the Red Cathedral Cactus involves allowing the soil to dry out completely between waterings, often referred to as the “soak and dry” method. Overwatering is a common issue that can lead to root rot. During the active growing season in spring and summer, water approximately weekly, ensuring the pot has drainage holes. In the dormant season of fall and winter, reduce watering significantly to once every three to six weeks, or when the soil is completely dry.
Ideal Soil Mix
The Red Cathedral Cactus requires a well-draining soil mix to prevent waterlogging and root rot. A commercial cactus or succulent potting mix is ideal. To further enhance drainage, amendments like perlite, pumice, or coarse sand can be added to a standard potting soil at a ratio of 2:1:1 (potting mix:perlite:sand). Adequate drainage holes in the pot are also essential.
Temperature and Humidity
This plant thrives in warm temperatures, ideally between 65°F to 85°F (18°C to 29°C). While it can withstand brief temperature drops, it is not frost-hardy and should be protected from temperatures below 40°F (4°C). The Red Cathedral Cactus tolerates average household humidity levels and does not require high humidity or misting. Maintaining good air circulation helps prevent fungal issues, especially indoors.
Feeding Your Plant
The Red Cathedral Cactus is a light feeder, requiring minimal fertilization. During its active growing season in spring and summer, apply a balanced, low-nitrogen liquid fertilizer or a cactus-specific fertilizer. Dilute the fertilizer to half strength and apply it once a month or every four to eight weeks. Avoid fertilizing during the fall and winter months when the plant is dormant, as this can lead to salt buildup in the soil and potentially harm the roots.
Propagating Red Cathedral Cactus
Propagating the Red Cathedral Cactus is typically done through stem cuttings. Select a healthy stem section, at least 4 to 6 inches long, and use a clean, sharp knife or scissors to make a clean cut. Allow the cut end to callus over for several days in a dry, shaded location; this prevents rot. Once a callus has formed, plant the cutting about an inch deep into a small pot filled with a well-draining cactus or succulent mix. Water sparingly initially, allowing the soil to dry out completely between waterings, until roots begin to establish, which may take a few weeks.
Common Problems and Troubleshooting
Red Cathedral Cactus plants can experience a few common issues. Overwatering is a frequent problem, leading to root rot, which manifests as yellowing stems or a mushy base. To resolve this, ensure the soil dries thoroughly between waterings and consider repotting into fresh, well-draining soil if rot is severe. Insufficient light can cause etiolation, where the plant stretches and becomes leggy, indicating a need to move it to a brighter location. Pests like mealybugs or spider mites may appear; these can be managed by regular inspection and treating affected areas with isopropyl alcohol or neem oil.
Safety Considerations
The Red Cathedral Cactus, like other Euphorbia species, produces a milky white sap, known as latex, when its stems or leaves are damaged. This sap is an irritant and can cause skin irritation, rashes, or blistering upon contact. It is also toxic if ingested, posing a risk to both humans and pets. When handling or pruning the plant, wear protective gear, such as gloves and eye protection, to prevent exposure to the sap. Should the sap come into contact with skin, wash the affected area immediately with soap and water. Keeping the plant out of reach of children and pets is important.