By Jeanne Lawrence, UC Master Gardener of Butte County, July 13, 2018
Summers are getting hotter in much of the U.S., including our local environment. One way to counteract this change in climate is by planting trees to provide more shade in the summer months. But adjusting to a shadier garden also means shifting to different plant choices. While it is true that most colorful garden flowers (like roses, zinnias, poppies, and hollyhocks) require full sun, there are still many options for blooms available to the shade gardener. White flowered gardenias and pink or blue flowering hydrangeas are common shade plants in our area. Here are some less obvious selections of shrubs that are easy to care for and can provide interest in the shade garden at different times of the year:
Sarcococca ruscifolia with berries, Wikipedia
A great small shrub for very shady areas is Sarcococca (sweet box). It is evergreen, with dark green leaves and tiny white flowers that appear in late winter or early spring and are very fragrant. Following the flowers are red berries. Once established, Sarcococca will tolerate dry shade. It is especially lovely planted in groups or as a small hedge; several of these shrubs growing together maximizes their scent, which has been compared to that of sweet vanilla. S. ruscifolia is slow growing, but can eventually reach six feet tall and wide; S hookeriana humilis is a much shorter shrub, growing to perhaps one and a half feet. This variety will spread by underground runners to create a good ground cover over time. Sarcococca is a perfect choice for deeply shaded areas under eaves and overhangs, alongside entryways, and under low-branching evergreen trees.
Kerria japonica pleniflora, Wikipedia
For a spot in the garden that would benefit from some bright color in spring and early summer, consider Kerria japonica. This is a deciduous shrub, but its bright yellowish-green stems provide color in the winter months. Triangular bright green leaves emerge in early spring on thin arching branches, followed by golden yellow blossoms that resemble small roses about an inch in diameter. K. japonica ‘Pleniflora' is commonly found in local nurseries. It can grow eight to ten feet tall and wide, with graceful arching branches covered with double yellow blossoms. Plant K. japonica in a partially shaded spot, where it will get at least four but no more than six hours of sun each day, preferably in the morning hours, or in the early evening after the hottest time of day. After flowering is completed, cut the branches that have flowered back to the ground, allowing this shrub to retain its arching habit.
Spiraea thunbergii in flower, Wikipedia
The genus Spiraea includes many species that do well in lightly shaded areas in our climate. There are two main types of Spiraea: those with long, graceful, arching branches lined with clusters of tiny white flowers (these are often referred to as the “bridal wreath type”); and those with a shrubby growth habit which produce clusters of white, pink or red blossoms at their branch ends. Both types are deciduous, and the leaves of many of these species turn bright shades of red, orange, or yellow in the fall.
Spiraea japonica Anthony Waterer
Spiraea thunbergii is a bridal wreath type that can reach six feet high and wide, with many thin, arching branches. In early spring, the bare branches are lined with clusters of tiny white flowers. These are followed by very narrow, inch-and-a-half-long, blue-green leaves that turn yellow or reddish brown in the fall. Another stunning bridal wreath type is the fast-growing S. x vanhouttei. On this shrub, diamond-shaped blue-green leaves emerge first, followed by flat clusters of white blossoms covering the plant in mid to late spring.
A notable shrubby type of Spiraea is S. japonica ‘Anthony Waterer.' Reaching three to five feet high and wide, it produces two-to-three-inch wide clusters of deep pink blossoms in late spring and early summer, and will produce another crop of blossoms if spent flower clusters are reliably pruned out. While ‘Anthony Waterer' has bright green foliage, similar pink-flowering varieties have been developed with quite remarkable leaf color. For example, ‘Goldflame' and ‘Goldmound' have bright yellow-green foliage, and the leaves of ‘Limemound' emerge lemon yellow, then turn to lime green.
Spiraea vanhouttei flowers and foliage, Wikipedia
By planting several different species of Spiraea, you can have blooming shrubs in shadier areas of the garden from early spring into summer, with the added bonus of beautiful fall colored leaves, and often, brightly-colored bare stems in winter.