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Arizona Rainbow Hedgehog, Sonoran Rainbow Cactus, Cabeza de Viejo
Echinocereus rigidissimus

Family: Cactaceae (kak-TAY-see-ee) (Info)
Genus: Echinocereus (ek-in-oh-KER-ee-us) (Info)
Species: rigidissimus (rig-id-ISS-ih-mus) (Info)
Synonym:Echinocereus rigidissimus subsp. rigidissimus
Synonym:Cereus pectinatus var. rigidissimus
Synonym:Echinocereus pectinatus var. rigidissimus

Category:

Tropicals and Tender Perennials

Cactus and Succulents

Height:

6-12 in. (15-30 cm)

Spacing:

3-6 in. (7-15 cm)

6-9 in. (15-22 cm)

Hardiness:

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Sun Exposure:

Full Sun

Sun to Partial Shade

Light Shade

Danger:

Plant has spines or sharp edges; use extreme caution when handling

Bloom Color:

Magenta (Pink-Purple)

Red

Bloom Time:

Late Spring/Early Summer

Mid Summer

Foliage:

Unknown - Tell us

Other details:

This plant is suitable for growing indoors

Drought-tolerant; suitable for xeriscaping

Suitable for growing in containers

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:

Non-patented

Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

Allow cut surface to callous over before planting

From seed; direct sow after last frost

Seed Collecting:

Allow unblemished fruit to ripen; clean and dry seeds

Unblemished fruit must be significantly overripe before harvesting seed; clean and dry seeds

Regional

This plant has been said to grow in the following regions:

Chandler, Arizona

Hereford, Arizona (2 reports)

Maricopa, Arizona

Patagonia, Arizona

Phoenix, Arizona (2 reports)

Rio Rico, Arizona

Scottsdale, Arizona

Tucson, Arizona (2 reports)

Canoga Park, California

Hesperia, California

Spring Valley, California

show all

Gardeners' Notes:

1
positive
0
neutrals
0
negatives
RatingContent
Positive

On Apr 23, 2005, Xenomorf from Valley of the Sun, AZ (Zone 9b) wrote:

The subspecies 'rigidissumus' has stems that reach over 4 inches thick with 15-23 radial spines per areole.
The subspecies 'rubispinus' has stems that only get about 2 1/2 inches thick with 30-35 radial spines per areole. The spines are also more Ruby/pinkish colored compared to the 'rigidissimus' subspecies.
The flowers on both are bright pinkish-red or magenta or red with white throats.

I've seen these growing in the wild on the West Ruby Road Trail in Arizona (South of Tucson), off of Interstate 19 through to Ruby, AZ and on to Arivaca, AZ.