Scientific: Cotoneaster horizontalis
Common: rock cotoneaster, rockspray cotoneaster
Family: Rosaceae
Origin: China
Pronounciation: Ka-tone-ee-ASS-ter hor-i-zone-TAL-is
Hardiness zones
Sunset 5-24
USDA 6-11 (though limited in zones 9-11 by intense summer heat)
Landscape Use: For use in Arizona landscapes between 2,500 feet and 6,000 feet in elevation in towns and communities ranging from Benson and Wilcox to Payson, Prescott, and Kingman. Not for landscape use in the lower desert cities of Phoenix, Tucson, or Yuma because of the intense summer heat. Primarily used as a larger-scale landscape shrub ground cover, slope cover, hanging over retaining walls, some color accent.
Form & Character: Rock cotoneaster is prostrate and spreading, mounding, trailing, a bit oriental and informal, can be stiff.
Growth Habit: Mostly evergreen to partially deciduous, woody perennial shrub, moderately spreading to as much as 10 to 15 feet in width with an ultimate mature height of only 2 to 3 feet.
Foliage/Texture: Leaves very small, green to dark green, ovate to lanceolate shaped with entire margins, glabrous but with some pubescence especially when young, sessile, stiff branches; fine texture.
Flowers & Fruits: Clusters of perfect white flowers with a pinkish tinge, 5 petals, mostly terminal and axillary, small to 1/2 inch in diameter; fruit is a small orange to red pome.
Seasonal Color: Masses of showy, small white flowers in spring followed by a very subtle fruit display in autumn. Sometimes during colder weather the foliage with turn a deep scarlet red to almost purple.
Temperature: Tolerant of only mild heat to 105oF, but cold tolerant to near 0oF.
Light: Full sun
Soil: Tolerant of some soil alkalinity, though grows well in almost any soil texture provided drainage is good.
Watering: Regular irrigations especially in arid Arizona landscape.
Pruning: Head back to control spread as needed. Lightly shear to shape....only rarely. DO NOT frequently shear!
Propagation: Mostly by cutting, some seed.
Disease and Pests: Fireblight is a rare problem in Aizona landscapes, spider mites.
Additional comments: At its best, rock cotoneaster is a serviceable prostrate shrub for mid-elevation Arizona communities. Flowers attract bees.
Some outstanding cultivars include:
