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FACTORS TO CONSIDER WHEN SELECTING TREES AND SHRUBS
While spring is an excellent time to plant trees and shrubs, not too many people know that fall is also a great time plant. Before going to your local nursery, contractors who maintain commercial properties should do some research. ContractorPartners should examine the planting site, determine their landscape needs, and obtain specific information on the plant materials. Some important plant characteristics are size, hardiness, susceptibility to insects and diseases, and soil conditions. Careful plant selection can create an attractive landscape and prevent future maintenance problems.
Size
Knowledge of the mature height and spread of trees and shrubs can prevent many landscape problems. The mature height and spread of trees and shrubs will vary somewhat due to soil conditions and other factors. However, knowledge of their approximate mature size can prevent overcrowding, interference with overhead utility wires, obstruction of vehicular and pedestrian traffic, and other problems. Properly selected plant materials also have longer life spans and require less maintenance.
Hardiness
An important consideration when selecting trees and shrubs is their cold hardiness. Michigan for example, occupies USDA Hardiness Zones 4 and 5. The average minimum temperature in Zone 4 is -20 to -30°F. The average minimum temperature in Zone 5 is -10 to -20°F. Select trees and shrubs that are reliably hardy in your area. Tolerance to summer heat and drought also can be important. The white-barked birches and the European mountain ash prefer cool, moist environments. Hot, dry weather weakens the trees. The weakened trees are then destroyed by insects or diseases. Because of their poor tolerance to heat and drought, the white-barked birches and European mountain ash are not recommended very often in the Mid-West.
Pest Susceptibility
Another important consideration when selecting trees and shrubs is their susceptibility to insects and diseases. In the last 10 to 15 years, pine wilt has become a serious disease of Scotch pine (Pinus sylvestris) in Michigan and other midwestern states. Pine wilt is a fatal disease that quickly kills infected Scotch pines. Other pine species that are occasional victims of pine wilt include jack (Pinus banksiana), mugo (Pinus mugo), Austrian (Pinus nigra), and red (Pinus resinosa) pine. Unfortunately, there are no effective treatments for the prevention or control of pine wilt. The best strategy is to contain the disease by promptly removing and destroying dead or dying Scotch pines. Because of pine wilt, Scotch pines are no longer recommended for windbreaks and home landscapes. White pine, spruces, firs, and arborvitae would be better choices for Michigan and other Mid-West states.
Soil Conditions
Soil conditions at the planting site strongly affect trees and shrubs. Most trees and shrubs grow well in soils with a pH of 6.0 to 7.5. However, there are exceptions. Pin oaks require a pH of 5.5 to 6.5. Another important soil characteristic is soil porosity. Select appropriate plants for wet and dry sites. For example, River Birch, Green Ash, Sycamore, and Redosier Dogwood do well in wet sites. Red Cedar, Crabapple, Hawthorn, and
Potentilla tolerate dry soils.
Publications are available at your local county extension office on each of these topics. One of the most comprehensive reference books available is Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses by Michael Dirr. This book may be available at your local public library or can be purchased at bookstores and online.
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