Denmoza rhodacantha (Salm-Dyck) Britton & Rose
Cereus erythrocephalus, Cereus rhodacanthus, Denmoza erythrocephalus, Echinocactus rhodacanthus, Echinopsis rhodocantha, Pilocereus erythrocephalus
Denmoza rhodacantha is a cactus that slowly grows up to 5 feet (1.5 m) tall. It starts as a globular cactus and stays that way for quite some time before growing into a column. The stem is pale green to dark green, up to 1 foot (30 cm) in diameter, and has 15 to 30 ribs. The spines are brownish-red, becoming grey, awl-shaped, and slightly curved. The flowers are tubular, bright red with white hairs, and up to 3 inches (7.5 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. Make sure 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. Cut away the affected parts and replant them. 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.
Denmoza rhodacantha is native to Argentina.
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