Echinocereus rigidissimus (Engelm.) F.Haage
Arizona Rainbow Cactus, Rainbow Hedgehog Cactus, Sonoran Rainbow Cactus
Echinocereus rigidissimus subsp. rigidissimus, Echinocereus rigidissimus var. rigidissimus, Cereus pectinatus var. rigidissimus, Echinocereus pectinatus var. rigidissimus
Echinocereus rigidissimus is a beautiful cactus with a usually solitary stem with pectinate radial spines curved slightly towards the stem. It grows up to 12 inches (30 cm) tall and 4.4 inches (11 cm) in diameter. New spines are reddish to magenta and fade to a yellow or light pink when they mature. This cactus blooms in flushes throughout the spring, with multiple buds borne atop the plant from younger areoles. Flowers are bright pink with a white throat.
USDA hardiness zones 9a to 11b: from 20 °F (−6.7 °C) to 50 °F (+10 °C).
How to Grow and Care
If you can successfully grow other globular cactus, you can most likely grow Echinocereus well. One of the key factors in success with these is avoiding any hint of wet soil. Because their root systems are weak, they are especially prone to root rot, eventually killing your plant. Otherwise, they thrive on a program of strong, bright light, slight water, and a steady diet of light fertilizer. These cacti are vulnerable to mealybugs and aphids.
Echinocereus are slow-growing cacti that should only need repotting every other year or so. You can prolong the time to repotting by removing plantlets and potting them up in their own pots. When repotting a cactus, carefully remove it from its pot and knock away any clumped soil. These plants tend to be shallow-rooted with weak root systems, so take care not to damage their roots.
Learn more at How to Grow and Care for Echinocereus.
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