According to Beth R. Jarvis, horticulturist with the University of Minnesota, planting shrubs in heavy clay soil is a backbreaking task. Clay soil is heavy to dig and hard for roots to penetrate. It does not drain quickly, holds water and may drown shrub roots. Jarvis says success depends on using plants tolerant of clay soils.
Choose clay-tolerant barberry for a dense, upright plant requiring little care. Horticulturist Christopher Starbuck, University of Missouri, recommends barberry for its rugged ability to thrive in almost any soil. From dwarf red-leaf varieties to 8-foot aromatic bushes, the barberry shrubs have thorny twigs for protective hedges and fruit more heavily in poor soil. These shrubs have semi-evergreen foliage lasting into winter. These plants offer ornamental foliage and fruit.
Select honeysuckle plants, woody plants with both bushy growth and vine-climbing cultivars. According to the University of Missouri, honeysuckle plants are useful as shrub borders and screening plants. These plants grow easily in clay and quickly fill a fence, trellis or hedge. Honeysuckle offers fragrant spring flowers for pollinators such as bees and hummingbirds. These plants produce colorful berries in summer and autumn that provide food for birds. Honeysuckle is low care, though it may require pruning in temperate climates.
Lilac is one of the best-known flowering shrubs. With hundreds of varieties and flower colors ranging from white through purple, the fragrant lilacs flower in late spring and thrive in clay soil. Horticulturist Starbuck advises that lilacs need proper and sometimes heavy pruning to maintain their shape and encourage flower production. Once a lilac is established, Starbuck recommends cutting back 1/3 of the shrub each year. The clay-loving lilac can grow over 8 feet tall.
Other shrubs are especially well-suited to clay soil. The University of Minnesota reports dogwood shrubs and forsythia meet these requirements. Forsythia are fast-growing shrubs that grow from cuttings stuck in moist clay soil. Their profuse yellow flowers bloom early in spring. Other shrubs such as chokeberry, winterberry and privet are grown for their attractive hedge-like foliage and are noted for their colorful berries. These berries are important bird-food sources in some regions. Easy-growing spirea shrubs grow 3 to 5 feet high and form mound-shaped shrubs. They grow in any soil and do especially well in clay and cobble clay, a rock-strewn clay soil. Many other shrubs will tolerate clay soil if their root crowns are slightly raised above the soil level and they are drip-irrigated to limit moisture in the water-retentive clay.