Cotoneaster horizontalis aka Rock Cotoneaster

Cotoneaster horizontalis is a woody shrub in the rose family. Gardeners also call it rock cotoneaster or rockspray cotoneaster. It comes from central and southern China and Taiwan. Most garden plants reach 2–3 feet [0.6–0.9 metres] tall. They spread 6–8 feet [1.8–2.4 metres] across. Reports also describe heights of 6 feet [1.8 metres]. Some plants spread beyond 10 feet [3 metres]. Most sources describe slow growth, though UConn reports faster growth.

The shrub forms a dense, low mound with spreading branches. Its flat sprays develop tiers as the plant ages. Small side branches form a pattern like a fish skeleton. Smooth gray bark covers older stems. Young stems range from green to reddish brown. The small, glossy leaves are dark green, round or oval. Each leaf grows alone, alternating along the stem. Leaves turn red or purple before falling in cooler regions. Plants may keep some or all leaves in warmer areas.

Small flowers open in May and June, close to the branches. They grow alone or in pairs and have five petals. Their colour ranges from pale pink to white with pink tints. Bees visit the flowers. Bright red pomes appear from late summer into autumn. These oval fruits measure about a quarter-inch across. Birds eat them, and some fruits remain through winter. Flowers, fruit and autumn leaves each add seasonal interest.

Grow this shrub in full sun or partial shade. It prefers loose, moist loam with good drainage. It also tolerates poor soil, clay, sand and varied pH. Established plants cope with drought, but hot summers can cause poor growth. Most sources place it in USDA zones 5–7. Chicago Botanic Garden gives a wider range of 4–7. The RHS rates its UK hardiness as H7. A well-sited plant needs little pruning. Stem cuttings offer a way to raise more plants.

Gardeners use it as groundcover on banks and slopes. Its spreading growth can help limit soil loss. Branches can trail over rocks or stone walls. It also suits borders, group plantings and training as an espalier. Fireblight, leaf spot and canker can damage plants. Lace bugs, webworms and mites may also cause problems. Hot, dry sites favour mite trouble. Dense branches can trap dead leaves and other debris. Seedlings may need removal where plants sow themselves. Great Britain lists this species as invasive. There, causing it to grow in the wild is unlawful. The fruit is not food for people or pets. Eating it can upset the stomach.