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Photo by Stan Shebs

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Petrophytum caespitosum

Also Known As

Petrophyton caespitosum
Petrophyton caespitosum subsp. caespitosum
Petrophytum caespitosum subsp. caespitosum
Dwarf Spiraea
Mat Rock Spiraea
Rocky Mountain Rockmat
Tufted Rockmat

Plant type

shrub, perennial, groundcover

size

H: 1"-6"
W: 2"-6'

planting zones

4a-9b

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Petrophytum caespitosum plant details

Petrophytum caespitosum is a broadleaf deciduous, evergreen or semi-evergreen perennial groundcover shrub with blue and green foliage. In summer white flowers emerge. Grows well with sun and low water. Drought tolerant once established. Does well in average, gritty, rocky and well-drained soil. A good option if you're seeking something verticillium wilt resistant.

CHARACTERISTICS OF Petrophytum caespitosum

Plant type: perennial groundcover shrub
Plant family: rosaceae
Foliage: deciduous, evergreen or semi-evergreen blue and green
Mature size: 2 IN - 6 FT - wide, 1 IN - 6 IN - tall
Flowers: white blooms in summer
Uses: easy-to-grow, mat-forming, rock garden, showy

GROWING CONDITIONS for Petrophytum caespitosum

USDA Zones: 4a - 9b
Sun exposure: sun
Watering frequency: low
Resistant to: verticillium wilt
Soil needs: average, gritty, rocky and well-drained

Nursery contributed plant descriptions

One of the tiniest of rosaceous shrubs exceeded only by Kelseya, these are from a Bradshaw collection in Johnson Co WY at 8200'. Unlike Kelseya, Petrophytum is a relatively easy to grow calciphile; forming mats 20cm across in 10 years, the silky downy foliage topped with tiny white plumes like a miniature Astilbe or Spirea. A classic plant that deserves a prime place in the garden. ZONE 4