Oklahoma’s USDA Zone 7 gardens are not southern gardens like the ones in Georgia but they are not western Arizona gardens or northern gardens either. The USDA Zones were assigned to areas based on average minimum winter temperatures.
Perennial plants that are cold hardy to zone 7 are also cold hardy in zones 8 and 9 and many plant tags indicate a range of zones. But there are other considerations for successful selection, including heat, humidity, snow cover, hours of sun and soil.
Trees and shrubs, the perennial foundation of a garden, provide the central bones that flowers and grasses grow around.
Each variety of a shrub such as Crapemyrtle is chosen for its leaf or flower color, or for the beauty of its peeling bark. For example, Pocomoke grows 3-feet and Kiowa grows 30-feet tall.
Some research will help you select the right shrubs and trees.
Ashe Magnolia (Magnolia ashei) trees are hardy from zones 6 to 9 and grow 10 to 20 feet tall with 12-inch fragrant flowers and 24-inch long leaves. Shady, moist location.
Bell-Flowered or Taiwan Cherry (Prunus campanulata) tree has rose flowers followed by small red fruit for the birds. Its maximum height of 20-feet makes it an ideal tree for small gardens. Okame and Dream Catcher varieties are hardy in zones 5 to 8.
Flowering Crabapple (Malus) Mary Potter has white flower clusters that attract butterflies. Grows 10 feet tall and 20 feet wide. Prairiefire has pink flowers and tiny red fruit. Grows 20-feet tall and wide in full sun. Zones 4 to 8.
Abelia x grandiflora: Kaleidoscope, Little Richard and Rose Creek grow 3 feet tall and wide. The leaves are lime green with white edges. Soft pink flowers. Container plants, hedge or foundation plants. Attract hummingbirds and butterflies. Zones 6 to 9; evergreen in Zone 7.
Witherod Viburnum (Viburnum cassinoides) is a round shrub with arching branches and dark green leaves that turn red in the fall. The new shoots are chocolate colored, the white flowers are 2-inches across. The fall berries are pink, blue and purple. Grows 6 feet tall and wide.
Mock Orange (Philadelphus), hardy in zones 5 to 9, is a deciduous shrub that likes some shade. Avalanche is multi-stemmed and grows 4-feet wide and tall with white, scented flowers. Good for foundation plantings, borders or low screening.
Needle Palm (Rhapidiophyllum hystrix) is noted for winter hardiness to zone 6, if it is planted in a protected spot out of the wind. It has a rounded shape with needlelike spines and dark green leaves. Each blade can grow to 3-feet across. Grows 6 feet tall and wide. Needs mulch in harsh winters.
Japanese aralia, Fatsia japonica, loves moist shade and will grow 6 to 8-feet tall with lobed leaves a foot wide. Good patio plant. Mulch roots in winter.
Smoketree, Cotinus coggygria 'Velvet Cloak' is a shrub that can be pruned into a tree form. The flowers are billowy and look like smoke. 10-feet tall with purple leaves.
Books by Michael Dirr: “Dirr’s Trees and Shrubs for Warm Climates: An Illustrated Encyclopedia” and “Hardy Trees and Shrubs”. www.TimberPress.com
Online - Missouri Botanical Garden at http://www.mobot.org/ and Plants of Merit at www.plantsofmerit.org/index.cfm/fuseaction/plants.main/index.htm. St. Louis is Zone 6a and their recommended plants are good selections for northeast OK.
Oklahoma Gardener Magazine - http://statebystategardening.com/ and 888-265-3600
Oklahoma Proven Selections http://oklahomaproven.okstate.edu/ and http://www.oklahomagardening.okstate.edu/
What are your favorite trees and shrubs? Will you be adding any this spring?