World Plants

Cotoneaster horizontalis (Rockspray or Rock Cotoneaster)

Michael's Opinion

Known as the Rocky or Rockspray Cotoneaster and belonging to the Rosaceae family, Cotoneaster horizontalis produces a beautiful pink flower in late spring and red berries that persist into the winter. This plant is found as a deciduous, semi-deciduous, semi-evergreen, to completely evergreen plant in southern locations. This specimen has beautiful attributes that work nicely in a residential or commercial landscape but use with caution as it can sometimes be a garbage collector in commercial landscape settings where its foliage will trap all manner of debris.

Botanical Information

Family	Rosaceae
Genus	Cotoneaster
Species	horizontalis
Category	Woody
Type	Shrub (deciduous), Shrub (evergreen)
References
Origin	Western China, introduced to the western world in the 1880’s.
Pronunciation

Details

USDA Hardiness Zone	5-7
USDA Hardiness Ref.
Canadian Hardiness Zone	3a-7b
Canada Hardiness Ref.
RHS Hardiness Zone	H7 - H5
RHS Hardiness Ref.
Temperature (°C)	-20
Temperature (°F)	-28
Height	50 - 95 cm
Spread	160 - 260 cm
Growth	Fast
Flowering Period	May, June

Description and Growing Information

General Description	This plant is quite attractive year round, covered in pink flowers in late May and red clusters of fruit during the winter. It grows quite low to the ground, sometimes reaching 95 cm in height but can be trimmed to maintain a compact form in landscaped or formal areas.
ID Characteristic	The stems are arranged in a fish bone arrangement. Produces a rich, red pomme fruit.
Shape	Low growing and spreading horizontally.
Landscape	Rock Cotoneaster can be used as a groundcover, mass planting or espalier up a wall or fence.
Propagation	Scarify the seed in concentrated sulphuric acid for 90-180 minutes then stratify in moist peat soil for 90-120 days at a temperature of 5°C. Softwood cuttings can also be taken in early summer and should be planted immediately, using a rooting hormone for best results.
Cultivation	Well-drained sandy, loamy or clay soils in full sun to partial shade.
Pests	Fire blight, leaf spot, and spider mites can all be factors if planted in shady areas with poorly drained soils however, if planted in the sun with well-drained soils, those pests should not be a problem.
Notable Specimens	Holden Arboretum Mentor, Ohio, United States of America. Great Dixter Garden, East Sussex, England.
Habitat	Thickets on rocky slopes and dry mountains.
Bark/Stem Description	The grey bark is smooth on young stems becoming slightly ridged as it ages.
Flower/Leaf Bud Description	Small, appressed on the stem, grey-brown in colour, covered with 2 bud scales.
Leaf Description	The leaves are simple, alternate, and glabrous on top and pubescent below.
Flower Description	The pink, five petaled flower is quite small at 5 mm however, covers the plant nicely.
Fruit Description	The small, 5 mm, circular red pome fruit persists throughout the winter and can be an attractive attribute. They ripen in September through October.
Colour Description	Leaves are dark green in the summer, losing some of its leaves in winter, those remaining turn a purple/red colour. The bark is grey to brown.