The Golden Torch Cactus (Trichocereus spachianus, also known as Echinopsis spachiana) is a popular columnar cactus. Cherished for its striking appearance, robust growth, and impressive blooms, it adds a distinctive vertical element to arid landscapes and container gardens.
Key Characteristics
Trichocereus spachianus exhibits a distinctive columnar growth habit, typically forming multiple stems from its base. Individual stems are light green to yellowish-green, reaching heights of up to 6 feet or more and diameters of 2 to 2.5 inches. Each stem features 10 to 15 prominent, rounded ribs that contribute to its sturdy, architectural appearance.
Along the ribs, areoles bear short, sharp spines. Spines are typically white or pale yellow, with a central spine up to 1 inch long, surrounded by shorter radial spines. It produces large, funnel-shaped flowers, usually pure white, reaching 6 to 8 inches in length. These nocturnal blooms open at night, closing by morning, often appearing in late spring or early summer.
Cultivation and Care
Light
The Golden Torch Cactus thrives in bright, direct sunlight. At least six hours of direct sun encourages compact, healthy growth and robust flowering. Insufficient light leads to etiolation, where stems become stretched, pale, and weak. When moving a cactus to a sunnier location, gradually acclimate it over one to two weeks to prevent sunburn, which appears as bleached or browned patches.
Soil
Optimal soil for Trichocereus spachianus must provide excellent drainage to prevent waterlogging and root rot. A specialized cactus or succulent potting mix is ideal, formulated to dry quickly. Improve this base by incorporating inorganic amendments like perlite, pumice, or coarse horticultural sand at a 1:1 ratio with the potting mix.
Watering
Watering Trichocereus spachianus requires a “soak and dry” approach, allowing the soil to dry completely between waterings. During the active growing season (spring through early fall), water thoroughly until it drains from the pot bottom. Before watering again, ensure the top few inches of soil are completely dry. In cooler, dormant months (late fall and winter), significantly reduce watering frequency, often to once a month or less. Overwatering leads to soft, mushy stems, while underwatering may cause the plant to shrivel.
Temperature and Humidity
Trichocereus spachianus prefers warm temperatures during active growth, ideally between 65°F and 90°F (18°C to 32°C). It can tolerate higher temperatures with adequate ventilation. During winter dormancy, the cactus can withstand cooler temperatures, down to about 20°F (-7°C) for short periods, provided the soil remains dry. It thrives in dry climates and requires very low humidity; high humidity, especially with cool temperatures, increases fungal risk. Protecting the plant from frost is important; prolonged freezing temperatures cause irreversible tissue damage.
Fertilizing
Fertilize Trichocereus spachianus during its active growing season (spring through late summer). Use a balanced, low-nitrogen fertilizer for cacti and succulents, such as a 5-10-10 or 2-7-7 NPK ratio. Apply fertilizer every 4 to 6 weeks, diluting it to half or quarter strength to avoid root burn. Cease all fertilization in fall and winter dormancy.
Propagation
Propagating Trichocereus spachianus is commonly achieved through offsets or stem cuttings; seed propagation is also an option. Offsets, often called “pups,” naturally form at the base of the mature plant. To propagate an offset, carefully detach it from the parent plant with a clean, sharp knife, ensuring some root development if possible. For stem cuttings, select a healthy segment of the main stem or a branch and make a clean cut.
After taking an offset or cutting, allow the cut end to callus in a dry, shaded area for one to two weeks, until a dry, protective layer forms. This callusing prevents rot when planted. Once callused, plant the offset or cutting in a well-draining cactus mix, just deep enough to keep it stable. Place the newly planted cutting in a bright location with indirect light and withhold water until roots begin to form, typically within a few weeks. Seed propagation is a slower process, requiring consistent warmth and humidity for germination.
Common Problems
One of the most frequent problems with Trichocereus spachianus is root rot, primarily caused by overwatering or poorly draining soil. Symptoms include a soft, mushy stem, often starting from the base, and discoloration. To address root rot, unpot the plant, trim away soft, blackened roots, allow healthy roots to dry for several days, then repot in fresh, well-draining soil.
Etiolation, characterized by stretched, thin, and pale growth, indicates insufficient light. Correct this by gradually moving the plant to a brighter location. While etiolated growth will not revert, new growth will be compact and healthy if light conditions improve.
Pests like mealybugs and spider mites can also affect Trichocereus spachianus. Mealybugs appear as small, white, cottony masses, often in crevices, while spider mites cause fine webbing and tiny discolored spots on the stem. Treat both by wiping them off with a cotton swab dipped in rubbing alcohol or by applying an insecticidal soap for cacti.