Light
Full Sun
Needs at least 6 hours of direct sunlight daily. An unobstructed south-facing window or patio is ideal.
Reference image Opuntia erinacea
Grizzly Bear Cactus
Overview
Opuntia erinacea, commonly known as the Grizzly Bear Cactus or Mojave Prickly Pear, is a striking succulent subshrub belonging to the Cactaceae family 1. It is highly distinguished by its dense cover of long, flexible, hair-like white spines.
Taxonomy and Naming
First described by George Engelmann and John Milton Bigelow, this taxon is frequently treated by modern botanists as a variety of the widespread star-flowered prickly pear, designated as Opuntia polyacantha var. erinacea 2. The specific epithet erinacea derives from Latin for "hedgehog-like," referencing its extremely spiny pads.
Distribution and Habitat
This species is native to the southwestern United States (including Utah, Nevada, Arizona, and California) and northern Mexico 1. It thrives in high-elevation desert scrub, dry gravelly slopes, and arid plains.
Appearance
The plant forms low, spreading clumps of flattened, obovate to circular jointed pads. These pads are heavily armed with flexible, woolly, or thread-like spines that can reach up to 12 cm in length, creating a "shaggy" look 2. Large, showy flowers in shades of yellow, pink, or bronze appear in late spring.
Cultivation and Care
Opuntia erinacea requires full sun and extremely well-draining, gritty soil to prevent root decline. It is exceptionally cold-hardy, surviving sub-zero temperatures with ease, provided the substrate remains dry during winter dormancy 3.
Common Cultivation Mistakes
Overwatering is the single most common cause of failure, quickly leading to root rot. Insufficient sunlight will cause weak, elongated growth (etiolation) and prevent the development of its iconic dense, white spines 3.
References
Watering
14-45 Days
Water only when the substrate is completely dry. Keep nearly bone dry throughout the winter months.
Soil
Extremely well-drained, sandy and gritty cactus mix
Use a porous mineral substrate rich in coarse sand, pumice, and perlite with minimal organic matter.
Safety
Contact/Ingestion Risk
Non-toxic, but the microscopic barbed bristles (glochids) cause painful skin irritation and require careful handling.
Difficulty
Easy
Very easy to maintain, provided you avoid overwatering and provide abundant light.
Native Habitat
Southwestern USA, Utah, Nevada, Arizona, Mexico
Hails from the high-altitude rocky slopes, barren plains, and gravelly washes of the Mojave Desert and Great Basin.
Frequently Asked Questions
Can the Grizzly Bear Cactus be grown in a pot?
Yes, it can be grown successfully in wide, shallow pots with excellent drainage holes and very porous cactus soil.
How often should I water this cactus?
Water only when the soil is dry to the bottom (about every 10–14 days in summer). Stop watering almost completely in winter.
Is the Grizzly Bear Cactus cold hardy?
Yes, this species is extremely cold hardy and can survive outdoor winter temperatures down to -15°C (5°F) if kept dry.
Is it toxic to pets?
It is chemically non-toxic, but its tiny barbed glochids pose a physical hazard, easily embedding in paws or mouths.
How do I get it to bloom?
Provide maximum direct sunlight during summer and allow a cold, completely dry rest period during winter.
Why is my cactus shriveling?
Slight shriveling is normal in winter as a freeze-defense. In summer, it indicates extreme dehydration or root rot from overwatering.
What is the best soil mix?
An ideal mix is 50% pumice or perlite, 30% coarse sand, and 20% organic potting soil.
How fast does it grow?
It has a slow-to-moderate growth rate, producing a few new pads each year under optimal conditions.
Why are its spines falling off or getting shorter?
Inadequate sunlight causes new growth to have weaker, shorter, and less dense spines.
How do I remove the spines if they prick me?
Use tweezers for larger spines, or apply and peel off adhesive tape or warm wax to pull out the tiny, invisible glochids.