Acanthocereus tetragonus (L.) Hummelinck
Barbed Wire Cactus, Dildo Cactus, Night-blooming Cereus, Triangle Cactus, Sword Pear
Acanthocereus colombianus, Acanthocereus floridanus, Acanthocereus pentagonus, Acanthocereus pitajaya, Acanthocereus princeps, Cactus pentagonus, Cactus pitajaya, Cactus prismaticus, Cactus reptans, Cactus tetragonus, Cereus dussii, Cereus nitidus, Cereus pentagonus, Cereus pitajaya, Cereus princeps, Cereus prismaticus, Cereus reptans, Cereus tetragonus, Cereus undulatus, Cereus variabilis, Cereus vasmerii
Acanthocereus tetragonus is a columnar cactus with dark green stems that usually have 3 to 4 angles. It grows up to 23 feet (7 m) tall. The stems are up to 3 inches (8 cm) in diameter. Areoles are grey and up to 1.2 inches (3 cm) from each other. They bear 1 to 2 (sometimes 3) up to 1.6 inches (4 cm) long central spines and 6 to 8 (sometimes up to 10) up to 1 inch (2.5 cm) long radial spines. Flowers are up to 8 inches (20 cm) in diameter and up to 6 inches (15 cm) long. Outer tepals are greenish-white, inner tepals are pure white, and pistils are creamy white. Shiny, red fruits are up to 2 inches (5 cm) long.
USDA hardiness zones 9a to 11b: from 20 °F (−6.7 °C) to 50 °F (+10 °C).
How to Grow and Care
Like most cacti, Cereus are fairly low-maintenance and hardy. Ensure they receive enough water without becoming waterlogged, especially during the summer, and fertilize them for the best results. If the roots have become black or overly soft, the cactus could be experiencing root rot. Cutaway the affected parts and replant. Most gardeners interested in cacti should be able to cultivate these without much problem.
It may become necessary to repot your Cereus if it outgrows its container. If so, make sure the soil is dry, and then remove the pot. Knock away old soil and prune away any rotted or dead roots, then replace it in a new pot and backfill with fresh soil. Make sure not to overwater cacti planted in new pots, as this can lead to root rot. It should be left dry for about a week and then watered lightly.
These cacti propagate quite easily from cuttings. Simply sever a branch and replant in moist, well-drained soil.
Learn more at How to Grow and Care for Cereus.
Forms and Cultivars
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