By Elaine Mills, Extension Master Gardener
Photos by Elaine Mills unless noted
In Part I of this article, posted last week, we presented alternatives to some traditional foundation shrubs that are considered invasive in Arlington County and the City of Alexandria. In Part II, we consider alternatives to other overused non-native shrubs.
Alternatives to Other Non-Native Shrubs
An extremely popular non-native shrub in my neighborhood is Euonymus japonicus, especially the variegated cultivar ‘Aureomarginatus.’ While not invasive, this plant can be problematic when some branches revert to the green of the straight species, resulting in a patchy, diseased look. A very attractive native substitute with similar-sized glossy dark green leaves is Aronia melanocarpa (black chokeberry). This shrub, which grows from 3 to 6 feet, has three-season interest with pretty white flowers in spring, dark purple berries in summer, and red to purple fall foliage. It provides nectar and fruit for wildlife and additionally serves as the larval host for several Lepidoptera. ‘Low Scape Mound,’ a dainty cultivar that reaches only 1 to 2 feet in height, is an excellent edging plant for foundation plantings and other garden beds.
Another overused foundation plant is the ‘Otto Luyken’ cultivar of Prunus laurocerasus (cherry laurel), a native of southeastern Europe and southwestern Asia. Although it has generally been considered benign, Alexandria now includes it on the city’s Invasive Watchlist. A locally native alternative with similar attractive upright flower clusters is Clethra alnifolia (sweet pepperbush or summersweet). This upright to rounded shrub grows in moist to wet soil in either sun or shade and will even flower in dense shade. The intensely scented white flowers attract native bees, butterflies, and hummingbirds, making it a great addition to a pollinator garden. Its quilted green leaves turn yellow in the fall, and its fruit capsules add winter interest while supporting birds and small mammals. Several cultivars are available, including pink-flowered ‘Ruby Spice’ and diminutive ‘Hummingbird.’
Although widely available in nurseries, Taxus baccata (English yew) is a shrub that is best avoided due to the highly toxic nature of all its plant parts, including the seeds of its red berries. A preferred native substitute, Ilex verticillata (winterberry), has bright red fruit that decorates the plant from mid-fall into early spring, providing nutritious food for 48 bird species. Because it is a dioecious species with separate male and female plants, it is important to plant paired cultivars of both sexes, although the pollen of one male plant can fertilize flowers of multiple female plants.
As boxwood blight, a serious and contagious disease caused by a fungal pathogen, poses concerns for boxwood (Buxus spp.) shrubs in landscape plantings in Virginia, homeowners may want to consider native Ilex glabra (inkberry) as an alternative. The only evergreen shrub among the native hollies, inkberry displays lustrous dark green foliage and grows from 6- to 10-feet high, with small white flowers in May and June and berry-like drupes on female plants from September to March. (A male plant is needed nearby for fruit production.) The plant adapts to varying light and moisture conditions, and various cultivars are available with different growth habits. It provides cover and food for birds and nectar for bees.
Asian mophead hydrangeas (Hydrangea macrophylla) have attractive colorful blossoms in the spring but don’t provide any ecosystem services in the landscape. Two species of native hydrangeas offer both ornamental qualities and support for wildlife. Hydrangea arborescens (wild or smooth hydrangea), a 3- to 6-foot shrub, has similarly large clusters of white flowers that attract a variety of native pollinators. It is also the larval host for two species of moths. Hydrangea quercifolia (oakleaf hydrangea) is a somewhat larger plant, with long pyramid-shaped flower panicles that turn from white to shades of pink and then tan with age. Its inflorescences also draw a variety of bees, wasps, and syrphid flies.
Asian azaleas (Rhododendron spp.) are understandably one of the favored foundation shrubs in spring with their wide range of colorful blooms. While beautiful, they have no relationship with the local fauna. Two native azaleas that thrive in similar shady locations with acidic soil are Rhododendron maximum (rosebay rhododendron), which grows from 5 to 15 feet tall, and Rhododendron periclymenoides (pinxterbloom azalea), which reaches 3 to 6 feet in height. Both plants attract a variety of pollinators, such as bumble bees, butterflies, and hummingbirds, and pinxterbloom hosts 50 species of butterfly caterpillars, including hairstreaks and brown elfins. Also of note, the rhododendron is evergreen, and the pinxterbloom has fragrant blossoms.
Refer to the following photos to see how several Extension Master Gardeners have used some of the native plants mentioned above in their own foundation plantings.