Trees and shrubs have many important uses in every landscape. They provide shade, shelter, structure, shape and color to define the landscape and add interest.
Trees frame the view. A tree on either side of the house frames the house like a picture frame. Trees can also frame the view from the house to draw attention to a good view. Also, trees can screen out the not-so-attractive view in neighboring yards. Trees also provide privacy from neighboring houses. When ranch style houses were popular, a six foot fence provided plenty of privacy, but two and three story houses need trees to provide screening. Deciduous trees work well during the summer, but evergreen trees are needed for year round privacy.
Trees also provide shade. A large shade tree can lower the temperature by twenty degrees. Shade trees on the south and west sides of the house reduce the need for air conditioning. A deck or patio will be much more comfortable and useful if shaded in the afternoon and early evening. Deciduous trees are especially good on the south side since they let light through in the winter. Ash trees let in even more light in the winter than most deciduous trees.
Trees also provide shelter from strong winds. A row of evergreen trees on the east side of the house protects from the strong, cold winds in the winter. This reduces heating costs and helps protect plants from freeze damage.
Trees provide color from their flowers and also from leaves. Many deciduous trees have outstanding fall colors. Some evergreen trees have blue, yellow or purplish needles.
Trees grow in many shapes and sizes. Go to Schmidt Reference Guide, to download an excellent reference for deciduous trees.
Here are some of my favorite trees:
Columnar: deciduous: Armstrong Red Maple, Chanticleer flowering pear; evergreen: arborvitae, incense cedar, Irish yew, Italian cypress.
Pyramidal: deciduous: red maple, gingko; evergreen: deodar cedar, Austrian pine, spruce, red cedar.
Round: deciduous: ash, linden, Japanese maple, dogwood; evergreen: cryptomeria, coast pine, Tanyosho pine.
Spreading: deciduous: Kwanzan cherry, Mt. Fuji cherry, silk tree, Sargent crabapple.
Weeping: deciduous: weeping cherry, weeping crabapple; evergreen: weeping blue Atlas cedar, weeping sequoia.
Shrubs can provide everything that trees provide on a smaller scale, but they are more often used to define the landscape. The edges of a yard are usually lined with shrubs. Shrubs can also divide a landscape into different areas if they are short, or rooms if they are tall.
Shrubs are available in many different flower colors and flower seasons. It is possible to have different shrubs blooming every month of the year. See the Shrub Calendar of Color webpages for lists of shrubs arranged by blooming season and height.
These nurseries have excellent pictures and descriptions of shrubs in their catalogs.
Wayside Gardens (retail Ohio)
Forest Farm (retail Oregon)
Herbs for the Kitchen and Landscape