Echinocereus rigidissimus (Arizona Rainbow Cactus)

Scientific Name

Echinocereus rigidissimus (Engelm.) F.Haage

Common Names

Arizona Rainbow Cactus, Rainbow Hedgehog Cactus, Sonorian Rainbow Cactus

Synonyms

Echinocereus rigidissimus subsp. rigidissimus, Echinocereus rigidissimus var. rigidissimus, Cereus pectinatus var. rigidissimus, Echinocereus pectinatus var. rigidissimus

Scientific Classification

Family: Cactaceae
Subfamily: Cactoideae
Tribe: Pachycereeae
Genus: Echinocereus

Description

Echinocereus rigidissimus is a solitary growing cactus, that rarely branches or offsets with age. It grows up to 12 inches (30 cm) and up to 4.4 inches (11 cm) in diameter when mature, with pectinate radial spines curved slightly towards the stem. The new spines are initially reddish to magenta and fades to a yellow or light pink when they mature. It flowers in flushes throughout the spring season, with multiple buds borne atop the plant from younger areoles. The flowers are bright pink with a white throat.

Photo via wikipedia.org

Hardiness

USDA hardiness zone 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, which will eventually kill your plant. Otherwise, they thrive on a program of strong, bright light; slight water; and a steady diet of light fertilizer. Echinocereus is vulnerable to mealybugs and aphids.

Echinocereus are slow growing cactus 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… – See more at: How to Grow and Care for Echinocereus