Tree selection is one of the most important investment decisions a home owner makes when landscaping a new home or replacing a tree lost to damage or disease. Considering that most trees have the potential to outlive the people who plant them, the impact of this decision is one that can influence a lifetime. Match the tree to the site and both lives will benefit.
 

The question most frequently asked of tree care professionals is "What tree do you think I should plant?" Before this question can be answered, a number of factors need to be considered. Think about the following questions:
 

Tree Function

Trees make our environments more pleasant. Properly placed and cared for, trees increase the value of our real estate. A large shade tree provides relief from summer's heat, and when properly placed, can reduce summer cooling costs. An ornamental tree provides beautiful flowers, leaves, bark or fruit. Evergreens with dense, persistent leaves can be used to provide a windbreak, or a screen for privacy. A tree that drops its leaves in the fall allows the sun to warm a house in the winter. A tree or shrub that produces fruit can provide food for the owner and/or attract birds and wildlife into your home landscape. Street trees reduce the glare from pavement, reduce run off, filter out pollutants and add oxygen to the air we breath. Street trees also improve the overall appearance and quality of life in a city or neighborhood.

Form and Size

Frank Lloyd Wright, the famous architect, once made the comment, "form follows function." This is a good rule to remember when selecting a tree. Selecting the right form (shape) to complement the desired function (what you want the tree to do) can significantly reduce maintenance costs and increase the tree's value in the landscape. When making a selection about form, also consider mature tree size. Trees grow in a variety of sizes and shapes, as shown below. They can vary in height from several inches to several hundred feet. Select a form and size that will fit the planting space provided.
 


 
 
 
 

 

Depending on your site restrictions, there are hundreds of combinations of form and size to choose from. You may choose a small spreading tree in a location with overhead utility lines. You may select a narrow columnar form to provide a screen between two buildings. You may choose large vase-shaped trees to create an arbor over a driveway or city street. You may even determine that the site just doesn't have enough space for a tree of any kind.

Site Conditions

Selecting a tree that will thrive in a given set of site conditions is the key to long-term tree survival. The following is a list of the major site conditions to consider before selecting a tree for planting:
Soil Conditions. The amount and quality of soil present in your yard can limit planting success. In urban sites the topsoil often has been disturbed and frequently is shallow, compacted and subject to drought. Under these conditions, trees are continuously under stress. For species that are not able to handle these types of conditions, proper maintenance designed to reduce stress is necessary to ensure adequate growth and survival. Many garden centers will, for a minor charge, arrange to have soil samples taken from your yard. Samples are tested for fertility and pH (alkalinity or acidity). The tests will be returned with recommendations on ways to improve poor soil conditions with fertilizers or soil amendments (sand, peat moss or manure) and will also help your local nursery or garden center recommend tree species that will do well in the soils found on your site.
Exposure. The amount of sunlight available will affect tree and shrub species selection for a particular location. Most woody plants require full sunlight for proper growth and flower bloom. Some do well in light shade, but few tree species perform well in dense shade. Exposure to wind is also a consideration. Wind can dry out soils, causing drought conditions, cause damage to branches and leaves during storms, and actually uproot newly planted trees that haven't had an opportunity to establish root systems. Special maintenance, such as staking, or more frequent watering, may be needed to establish young trees on windy sites.
Human Activity. This aspect of tree selection is often overlooked. The reality of the situation is that the top five statistics related to tree death are caused by people. Soil compaction, underwatering, overwatering, vandalism, and the number one cause, planting the wrong tree, account for more tree deaths than all insect and disease related tree deaths combined.
Drainage. Tree roots require oxygen to develop and thrive. Poor drainage can remove the oxygen available to the roots from the soil and kill the tree. Before planting, dig some test holes 12" wide by 12" deep in the areas you are considering planting trees. Fill the holes with water and time how long it takes for the water to drain away. If it takes more than 6 hours, you may have a drainage problem. If this is true, ask your local garden center for recommendations on how to correct the problem, or choose a different site.
Space Constraints. Many different factors can limit the planting space available to the tree: overhead or underground utilities, pavement, buildings, other trees, visibility--the list goes on and on. Make sure there is adequate room for the tree you select to grow to maturity, both above and below ground.
Hardiness. Hardiness is the plant's ability to survive in the extreme temperatures of the particular geographic region in which you are planting the tree. Plants can be cold hardy and/or for southern regions, heat tolerant. Most plant reference books will provide a map of hardiness zone ranges. Check with your local garden center for the hardiness information for your region. Before you make your final decision, make sure the plant you have selected is "hardy" in your area.

Pest Problems

Insect and disease organisms affect almost every tree and shrub species. Every plant has its particular pest problems, and the severity varies geographically. These may or may not be life threatening to the plant. You should select plants resistant to pest problems for your area. Your local ISA Certified Arborist, tree consultant, or cooperative extension agent can direct you to information relevant to problem species for your location.

Species Selection

Personal preferences play a major role in the selection process. Now that your homework is done, you are ready to select a species for the planting site you have selected. Make sure you utilize the information you have gathered about your site conditions, and balance them with the aesthetic decisions you make related to your personal preferences. The species must be suitable for the geographic region (hardy), tolerant to the moisture and drainage conditions of your soil, resistant to pests in your area, and have the right form and size for the site and function you have envisioned. Remember, that beautiful picture of the tree you looked at in the magazine or book was taken of a tree that is growing vigorously because it was planted in the right place. If your site conditions tell you the species you selected won't do well under those conditions, don't be disappointed when the tree doesn't perform in the same way.
 


 

If you are having difficulty answering any of these questions on your own, contact your local ISA Certified Arborist, tree care professional, garden center, or county extension agent for assistance. Their assistance will help you to plant the "right tree in the right place." It is better to get them involved early and make the right decision, to avoid having to call them later to ask them if you made the wrong decision.

This brochure is one in a series published by the International Society of Arboriculture as part of its Consumer Information Program. You may have additional interest in the following titles currently in the series: Insect and Disease Problems; Mature Tree Care; New Tree Planting; Trees and Turf; Benefits of Trees; Tree Selection; Plant Health Care; Avoiding Tree and Utility Conflicts; Recognizing Tree Hazards; Why Hire an Arborist; Buying High-Quality Trees; Tree Values; Pruning Young Trees; Pruning Mature Trees; Why Topping Hurts Trees; Pruning Young Trees; Pruning Mature Trees; Avoiding Tree Damage During Construction; Treatment of Trees Damaged by Construction.
 

Developed by the International Society of Arboriculture (ISA), a non-profit organization supporting tree care research around the world and dedicated to the care and preservation of shade and ornamental trees. For further information, contact: ISA, P.O. Box 3129, Champaign, IL 61826-3129, USA.

1995 International Society of Arboriculture.
UPDATED FEBRUARY 2000