The variegated dogwood shrub (Cornus alba argenteo-marginata) is a large multi-stemmed shrub grown for the bright coral-red winter color of the new growth. It has an open loose form and spreads by suckers to form colonies. It can be planted in masses for color or used for screening unsightly items. Its common name is variegated tartarian dogwood.
The variegated dogwood shrub grows 7 to 9 feet tall and wide. The grayish-green leaves are edged in creamy white and turn reddish-purple in the fall. Flat clusters of yellowish-white flowers appear in late spring, followed by white- to bluish-colored berries in late summer.
The variegated dogwood shrub grows in zones 2 to 7 in any type of soil, although it prefers well-drained, evenly moist soil. The variegation of the foliage is retained longer in full sun, because the green pigmentation in the leaves develops faster in the shade. Shrubs with variegated foliage have less chlorophyll, grow slower and have fewer flowers than trees with solid-colored foliage.
Variegated dogwood shrubs should be planted from late fall to early spring, while they are dormant. They require little or no fertilizer but will grow better when a 2- to 3-inch thick layer of organic mulch is applied yearly. The old gray- or dull-colored stems should be removed at ground level each year to encourage coral-bright red new growth. Shoots that have reverted to solid green should be pruned out because they grow aggressively and will take over the variegated portion of the shrub.
Numerous diseases affect variegated dogwood shrubs, such as powdery mildew and leaf spots. Dogwood anthracnose causes leaf and twig blight, as well as cankers on the trunk and limbs of infected trees. Phytophthora root rot can cause the death of the diseased tree.
Dogwood borers are the most destructive pests of all dogwood trees. Moth larvae tunnel and feed under the bark of the trunk and older branches, causing extensive damage and the eventual decline of the affected tree. Dogwood twig borers, the larvae of dark green, long-horned beetles, tunnel through the bark of small twigs after they hatch, causing the twig to break and fall off. Leafhoppers, sawflies, scale insects and spider mites are other common pests of dogwood trees.