Rock Cotoneaster Plants

Plant taxonomy classifies rock cotoneaster as Cotoneaster horizontalis. The genus name thus doubles as part of the common name. Another common name is "rockspray" cotoneaster. These common names allude to the widespread use of Cotoneaster horizontalis as a rockery plant (i.e., a plant used in rock gardens).

Cotoneaster horizontalis plants are deciduous flowering shrubs.

The plant form of Cotoneaster horizontalis is horizontally-spreading (thus the species name, horizontalis). Rock cotoneaster plants have small, roundish leaves that provide a nice contrast with larger-leafed plants. The fall foliage of its shiny leaves ranges from reddish-orange to burgundy; the light pink blooms of late spring yield to equally shiny red berries (or "pomes"). The branching of rock cotoneaster is stiff and dense, giving the plant, overall, a rather bristly look. Stems shoot off the branches in what's often referred to as a "herringbone pattern." Rock cotoneaster reaches 3' in height, 15' in width.

Rock cotoneaster shrubs are cold-hardy to planting zone 5. Cotoneaster horizontalis is indigenous to western China.

Grow rock cotoneaster in moist but well-drained, loamy soil. Although cotoneaster plants are drought-tolerant once established, it's best not to abuse their "tolerance!" I.e., cotoneaster plants will profit from a touch of afternoon shade, even though they are considered plants for full-sun.

Rock cotoneaster shrubs offer a nice example of a plant with four-season interest. They produce flowers in late spring, and their unusual branching pattern hosts glossy green leaves in summer. But rock cotoneasters really come into their own in autumn. They bear both attractive fall foliage and berries in the autumn months. The red berries persist thereafter and remain attractive into early winter but may show signs of shriveling and discoloration by mid-winter. By late winter the berries may attract hungry wild birds.

Birds, bees and butterflies are all attracted by rock cotoneaster; but, fortunately, the plants are deer-resistant. Birds use cotoneaster berries as an emergency food source in winter.

Because they stay low to the ground, rock cotoneaster plants are often used as ground covers and in rockeries (rock gardens). But others have planted them up against walls, whether free-style or in espalier.

It is not necessary to prune cotoneaster plants. And if you do prune them, don't prune off the ends of the branches, as you would, say, with yews -- that would ruin their natural gracefulness.

That said, you might feel that a particular branch spoils the overall shape of the plant. In that case, follow the branch all the way back to the center of the shrub, and make your pruning cut there. The offending member will thereby be excised, without leaving an awkward stump behind.

"Cotoneaster" is a widely mispronounced plant name. The correct pronunication, technically, is cuh-TO-ne-AS-tuhr, but even my dictionary gives some legitimacy to the common mispronunciation, CAWT-tuhn-ES-tuhr. I myself used to pronounce the word that way, despite the fact that cotoneaster shrubs have nothing to do either with cotton or Easter! Others want to drop the first "e" altogether, fancying a juxtaposition of "cotton" and "aster."

Etymologically, "cotoneaster" comes from the new Latin word for "quince," cotneum, plus the suffix, -aster, meaning "imperfectly resembling." So a cotoneaster shrub is literally a plant that imperfectly resembles a quince.

By the way, if you've read up on rock cotoneaster, you've almost inevitably come across references to the arrangement of its stems as forming a "herringbone pattern" along each branch. Such references usually go unexplained, and the pictures provided (if any) fail to reveal a herringbone pattern (or any other pattern), because there's too much foliage in the way.

To remedy this, the 3rd picture in my mini-photo gallery is a closeup of a bare cotoneaster branch in winter (click the photo, above right, to access the mini-photo gallery). Look at the pattern that the young stems are forming. I suppose it's somewhat reminiscent of the herringbone pattern. But to my eye, it looks more like someone tried to form a row of V's along the branch, but failed! The left-hand strokes of the V's don't line up properly with the right-hand strokes -- so that they never intersect.