Greening Milwaukee

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 should be considered.

Why do you want to plant the tree?

Trees can serve a wide range of purposes, from providing beauty and bearing fruit, to reducing summer temperatures or serving as a windbreak. Street trees can reduce glare from the pavement, reduce run off, filter out pollutants, and add oxygen to the air we breathe. Street trees also improve the overall appearance and quality of life in a city or neighborhood. The tree’s purpose will affect the type of tree you choose.

What is the size and location of the planting site?

Trees grow in a variety of heights, from several inches to several hundred feet. Select a form and size that will fit the planting space provided. You may want a smaller tree in locations with overhead utility lines. Large trees may be chosen to create an arbor over a driveway or city street. Or, perhaps the site is not large enough for a tree of any kind.

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.

Go here for more information on selecting the right tree to fit your location.

What is the condition of the planting site?

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 on 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).

You can also have your soil tested by the UW-Extension office. The UW-Extension website has complete information on soil testing costs and where to send your soil for testing.

	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 trees perform well in dense shade. Exposure to wind can dry out soils causing drought conditions, cause damage to branches and leaves during storms, and uproot newly planted trees that haven’t had an opportunity to establish root stems.

	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, under watering, over watering, 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 in the areas you are considering planting trees. Fill the holes, at least 12 inches deep, with water and time how long it takes for the water to drain. If it takes more than 6 hours, you may have a drainage problem. Ask your local garden center how to correct these problems.

	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 elect to grow to maturity both above and below ground.

	Some of the information on this page came from publications from the International Society of Arboriculture. Used with permission.