Cactus · Sonoran native
Rainbow Hedgehog Cactus
Echinocereus rigidissimus · Cactaceae
Also called: Arizona Rainbow Cactus, Rainbow Cactus, Arizona Rainbow Hedgehog
Rainbow Hedgehog Cactus (Echinocereus rigidissimus) is a very low-water cactus native to the Sonoran Desert region well suited to Tucson and the low desert. It's a slow-growing cactus.
Rainbow Hedgehog Cactus at a glance
- Water use
- Very Low (established)
- Sun
- Full sun for best spine color and flowering; benefits from light afternoon shade at hot, reflected-heat Tucson exposures to avoid scald.
- Mature size
- 4-12 in H x 3-4 in W (usually solitary, occasionally with a few offsets; stem is short, stout, and barrel-like)
- Growth rate
- Slow
- Bloom
- Bright rose-pink to magenta with a white throat (large funnel-shaped flowers up to ~3 in across), Late spring to early summer (April-June).
- Cold hardiness
- Hardy to about 10 F (USDA zones 8b-11).
- Soil
- Demands fast-draining sandy, gravelly, or rocky soil; weak shallow root system is highly prone to rot, so avoid any hint of wet soil and heavy ground.
- Native range
- Southeastern Arizona and southwestern New Mexico into Sonora and Chihuahua, Mexico; typically in desert grassland, oak woodland, and rocky upper-Sonoran slopes rather than the hottest low flats.
- Best used as
- Showpiece accent / collector specimen, Container and trough culture, Rock and cactus gardens, Small-scale xeriscape focal points, Pollinator plantings
- Wildlife
- Showy spring flowers attract native bees and other pollinators; fruit eaten by wildlife.
- Toxicity
- Non-toxic. The dense, pectinate (comb-like) spines are the only concern.
How to grow Rainbow Hedgehog Cactus in Tucson & the low desert
Watering
Minimal once established; rely on rainfall with occasional deep watering only in extended drought. Keep dry in winter and avoid frequent summer irrigation, which causes fatal root rot.
Fertilizer & nutrients
Little to none. An optional very dilute low-nitrogen cactus feed once in spring is sufficient; over-fertilizing distorts the characteristic banding.
Pruning & care
None required. Remove any rotted or sunburned tissue with sterile tools and let it callus.
Notes
Named for the colorful horizontal bands of pink, white, and reddish spines that ring the stem like a rainbow. Slow, choice, and somewhat finicky about drainage — best treated as a showcase specimen or container plant in Tucson. Always purchase nursery-propagated plants; wild collection is illegal.
Sources: Arizona-Sonora Desert Museum; University of Arizona Cooperative Extension; SouthwestDesertFlora.com; Spadefoot Nursery (Tucson)