There are about 45 species of dogwoods. Most are shrubs or small trees. Several dogwoods are valuable additions to home landscapes. A list of suggested dogwoods for Iowa, along with a brief description of each, is provided below.
The Tatarian dogwood (Cornus alba) is an 8- to 10-foot-tall shrub. Plants produce small, yellowish white flowers in spring followed by bluish white, berry-like fruit. The Tatarian dogwood is grown chiefly for its red-colored stems in winter. (Plants should be pruned frequently as young stems possess the most vivid red color. As a general rule, prune out a few of the oldest stems each year in late winter.) Plants perform best in moist, well-drained soils in full sun. 'Argenteo-marginata' and Ivory Halo® are two cultivars that produce green leaves with creamy white margins.
The pagoda dogwood (Cornus alternifolia) is a large shrub or small tree. Its mature height and spread is 15 to 25 feet. The pagoda dogwood is native to northeastern Iowa. It is typically found at woodland edges and forest openings. Ornamental characteristics include a horizontal branching habit, yellowish white flowers in late spring, and reddish purple fall foliage. The pagoda dogwood performs best in moist, well-drained soils in partial shade. Protected locations and eastern exposures are generally the best planting sites. The cultivar Golden Shadows® possesses green leaves with golden yellow margins. Alternate-leaved dogwood is another common name for Cornus alternifolia.
Silky dogwood (Cornus amomum) is a native shrub commonly found along streambanks, wet prairies, and woodland edges. Silky dogwood produces flat-topped clusters of yellowish white flowers in spring. Its fruit is bluish with white blotches. Silky dogwood is a rounded shrub which grows approximately 6 to 10 feet tall with a similar spread. It is a good choice for moist to wet sites.
The corneliancherry dogwood (Cornus mas) is a large shrub or small tree. Plants commonly grow 20 to 25 feet tall and 15 to 20 feet wide. The corneliancherry dogwood produces small, yellow flowers in round, three-quarter-inch-wide clusters in early spring. When selecting a planting site, choose a location with a dark-colored background, such as a building or row of pine trees, to highlight the yellow flowers. See photo below. After flowering, oblong one-half- to one-inch-long, berry-like fruit develop. The fruit turn cherry red in late summer and are edible. The foliage of the corneliancherry dogwood is dark green in summer. Fall leaf color is inconsistent, occasionally an attractive purplish red. 'Golden Glory' is a profuse blooming, upright cultivar. The corneliancherry dogwood can be grown in full sun to part shade.
The gray dogwood (Cornus racemosa) is native to Iowa. It is an adaptable shrub which tolerates wet or dry soils, shade or sun. Gray dogwood reaches a height of 8 to 10 feet. It produces whitish flowers in late spring which are followed by small white berries. The fruit are produced on reddish pink stalks. The colorful stalks become noticeable after the fruit have been eaten by birds or fallen to the ground. The gray dogwood is a good choice for naturalizing as it spreads by suckers.
The bright red twigs of the redosier dogwood (Cornus sericea) set against a backdrop of newly fallen snow is a beautiful sight in winter. Native to Iowa, redosier dogwood grows 6 to 10 feet tall. Several colorful varieties are available. 'Cardinal' has bright, cherry red stems. 'Alleman's Compact' is a compact (grows four to five feet tall), red-stemmed variety. 'Flaviramea' has yellow stems. 'Silver and Gold' has green leaves with creamy white margins and yellow stems. Like the Tatarian dogwood, the redosier dogwood should be pruned frequently as the young shoots possess the best color.
A notable dogwood that is absent from the above list is the flowering dogwood (Cornus florida). The flowering dogwood is a beautiful tree that is widely planted in the southern United States. Unfortunately, the flowering dogwood is not reliably winter hardy in most parts of Iowa. Kousa dogwood (Cornus kousa) is a similar tree native to Asia that performs better than flowering dogwood in southern Iowa. This small tree gets 15 to 25 feet tall and wide. In late spring plants are covered in large 4" across. The bloom has four white "petals" that are actually bracts (the true flowers are small inconspicuous flowers clustered in the center of the flower). The bracts age to a pink color. In summer large red fruit up to 1 inch in diameter appears and is very ornamental. With age, the trunk develops a patchy exfoliating bark in gray, tan, and brown. Leaves turn a nice red to reddish purple in the fall.
Updated from an article that originally appeared in the June 12, 2011 issue of Horticulture and Home Pest News.