How to Grow and Care for Rockspray Cotoneaster

Rockspray cotoneaster, also known as wall cotoneaster, is a horizontally spreading shrub that offers four-season interest, producing light-pink flowers in late spring, glossy green leaves in summer, and attractive reddish-orange to burgundy foliage and berries in the autumn. The stiff and dense branching gives the plant a bristly look. The shrub grows best in full sun, well-drained soil, and thrives in low humidity. Plant them in spring to allow their shallow root system to establish before the winter. The berries are toxic to humans and animals, although birds do fine with them.

Rockspray Cotoneaster Care

Here are the main care requirements for growing a rockspray cotoneaster shrub.

• Place the shrub in well-draining soil.
• Plant shrubs 4 to 5 feet apart to give them room to spread into a solid mass.
• Water frequently as the shrub is becoming established.
• Prune to contain its rapid spread.

Warning

Cotoneaster horizontalis, part of the genus Cotoneaster Medik, is considered an invasive shrub in parts of the United States, including Minnesota, Washington, Oregon, and California.

Light

Give rockspray cotoneaster full sun for optimal berry production and fall foliage color.

Soil

This plant is not fussy about soil pH, although it generally performs best in soil with a roughly neutral pH. Its main soil requirement is good drainage. A loamy soil works best.

Water

Rock cotoneaster is a drought-tolerant shrub once established. But until it is established, water regularly to keep its soil evenly moist.

Temperature and Humidity

These plants struggle in hot conditions, so don't try to grow them south of zone 7. These plants do well in relatively low humidity; humid weather may cause fungal leaf spots, though this is rarely a life-threatening problem.

Fertilizer

Rock cotoneaster is not a heavy feeder. Add compost to the soil as needed.

Types of Rockspray Cotoneaster

The cotoneasters are a diverse group of plants and are roughly divided into ground-cover types (such as Cotoneaster horizontalis) and taller, more upright types.

Within the rock cotoneaster species, there are two varieties to consider. One is a naturally occurring variety (C. horizontalis var. perpusillus), which grows only 1 foot tall, making it an ideal ground cover plant. And there is a cultivar, 'Variegatus', which has two-toned leaves.

But there are also many species besides C. horizontalis:

• Cotoneaster dammeriis one of the shortest types, reaching just 8 to 12 inches tall (suitable for zones 5 to 8).
• C. divaricatus is one of the varietals that grow tall enough (up to 6 feet in height, with a spread of up to 8 feet) to be used as a hedge (suitable for zones 4 to 7).
• C. lucidus is another species commonly grown in hedges. It grows to be 6 to 10 feet high and wide (grow it in zones 3 to 7).
• C. salicifoliusis one of the taller examples, reaching 10 to 15 feet in height, with a spread of slightly less than that (suitable for zones 6 to 8).

Pruning

It is not necessary to prune cotoneaster plants for their health, but you may want to do so in the spring to contain their spread. And if you do prune them, don't trim off the stem tips, as this will ruin the naturally graceful shape. If you feel that a particular branch spoils the overall shape of the plant, follow the branch back to the center of the shrub and make your pruning cut there.

Rockspray cotoneaster is the type of bush that will strike down roots wherever one of its branches touches the ground. This enables it to spread fairly rapidly. If this is an undesirable trait for you, then you'll need to keep up with your pruning to restrict the bush's spread. If low-maintenance landscaping is a priority for you, you may wish to skip rockspray cotoneaster altogether and grow a less aggressive plant.

Propagating Rockspray Cotoneaster

The easiest way to propagate this plant is by stem cuttings. Take these easy steps:

1. In July or August, cut away some of the plant's healthy side shoots, cutting just below a leaf node. Remove the lower leaves.
2. Plant the cuttings into a gritty potting medium.
3. Cover the pot with a clear plastic bag or dome, and place it in a bright location.
4. When new shoots begin to appear, remove the cover and continue to grow indoors.
5. By the following spring, the new specimen will have a good root system and will be ready to be planted in the landscape.
6. Choose a permanent spot for your shrub when transplanting the young plant.

Growing Rockspray Cotoneaster From Seed

Growing this plant from seeds is a bit of a process. Take these steps:

1. Rough up the outer shell of the seeds by using sandpaper or by rubbing them in your hands with some sand. This is best done in the fall.
2. The seeds then need to be cold-stratified. Do this by placing them in a plastic bag along with some moist peat or vermiculite and storing the bag in the refrigerator for 3 to 4 months, or until the seeds sprout.
3. Once the seeds have sprouted, they can be placed in small pots filled with loamy soil.
4. Set the pots in a bright location where the temperature will hover around 75 degrees Fahrenheit. Keep the soil moist.
5. When the plants are about 1 inch tall begin putting the pot outdoors for progressively longer periods each day. After the plants can withstand around five hours of sunlight without wilting, place them in the ground in a permanent spot, spacing plants about 10 feet apart.
   

Overwintering

Aside from mulching around your plant before the temperatures get too low, rockspray cotoneasters do not require any special treatment during the winter months.

Common Pests & Plant Diseases

There are no serious insect or disease issues with rockspray cotoneaster, but it can be susceptible to some of the same problems that afflict other members of the rose family.

Spider mites and other types of mites can show up during hot dry summers, but they can usually be handled with regular blasting with water from a strong hose. The most serious insect pest is the cotoneaster webworm, which can skeletonize the leaves. Webs will be visible on leaves and branches. These pests are difficult to control, and usually require the application of a chemical pesticide.

Fire blight, leaf spots, and cankers may be problems. Branches showing signs of fire blight or canker should be removed and destroyed. Leaf spots may require treatment with a garden fungicide if the symptoms are severe.

How to Get Rockspray Cotoneaster to Bloom

From April to May, rockspray cotoneaster blooms with clusters of small, five-petaled pink flowers that attract bees and birds. By June, green, ¼ inch berries emerge that turn bright red by September and last into March, providing food for birds. To encourage the most flowering and fruiting, rockspray cotoneaster will do best in full sun.

Common Problems With Rockspray Cotoneaster

Rockspray cotoneaster is an easy plant to grow and once established, it will survive and thrive largely on its own, provided it doesn't suffer prolonged drought. But there are a few problems to be on the lookout for, including the following.

Browning Foliage and Branches

If the ends of the twigs or branches appear to look "tinged" by fire, and dead leaves and flowers are still attached, the plant is suffering from fire blight, a bacterial disease. You may also see oozing cankers. If only some parts of the shrub are affected, prune out diseased parts, disinfecting the pruning tool after each cut. If the entire shrub is dead, dig it out and discard. However, C. horizontalis is one of the types of this plant that is a bit more resistant to fire blight.

Yellowing Foliage

If the undersides of the plant's leaves are yellowing, there's likely a spider mite infestation that requires insecticidal soap.

Branch Dieback

Pests, such as scale, can feed on the sap of branches which can cause death to the branches and then the entire shrub. Control scale with horticultural oil. Branches that are dying back and are covered in pimple growths and structures could be affected by Botryosphaeria canker, The shrub could be under stress from excess drought. Prune infected parts.

Blistering

Yellowish or reddish-brown blistering on leaves can indicate microscopic blister mites (Phytoputus pyri) and requires horticultural oil.

From: thespruce