Cleistocactus smaragdiflorus (F.A.C.Weber) Britton & Rose
Cereus smaragdiflorus, Cleistocactus ferrarii, Cereus baumannii var. smaragdiflorus, Cereus colubrinus var. smaragdiflorus
This species is native to Argentina and Bolivia.
Cleistocactus smaragdiflorus is a shrubby cactus with slender, cylindrical, arching to creeping stems with 12 to 14 ribs and closely set clusters of spines along the ribs. It grows up to 6.6 feet (2 m) tall, densely branched at the base. The stems are up to 6.6 feet (2 m) long and 2 inches (5 cm) in diameter. Each yellow wooly areole bears 4 to 6 central and 10 to 14 radial spines. The central spines are yellowish to dark brown and up to 1.4 inches (3.5 cm) long. Radial spines are yellowish and 0.4 inches (1 cm) long. Flowers are red to pinkish with a greenish apex and appear in summer. They are tubular, up to 4 inches (10 cm) inches long, and up to 0.5 inches (1.2 cm) in diameter. Fruits are spherical, yellow to reddish, and up to 0.6 inches (1.5 cm) in diameter.
USDA hardiness zones 9b to 11b: from 25 °F (−3.9 °C) to 50 °F (+10 °C).
How to Grow and Care
Choose a location that gets full sun and has well-draining soil. During the spring and summer, water Cleistocactus when the top inch (2.5 cm) of soil dries out. During the fall, reduce watering to every five weeks if the ground dries out. In winter, keep your cactus dry, or the moist ground combined with the cool temperatures and dormancy may cause the roots to rot. Fertilize with a low-nitrogen fertilizer during the active growth period. A slow-release fertilizer applied in the spring will be sufficient for the whole year.
It is possible to propagate by cutting a small branch from a Cleistocactus and rooting it, but this inevitably leaves a disfiguring scar near the base of the main stem. If an offset is removed to be used in propagation, remember to let it dry for a week or so, letting the wound heal. Rooting usually occurs within 3 to 8 weeks. It is, therefore, best to raise Cleistocactus from seed. Be sure to get the seeds from a reputable source.
Learn more at How to Grow and Care for Cleistocactus.
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