As we approach Arbor Day on April 26, many may be considering adding a tree, or maybe several trees, to their landscape. Important pre-steps to planting are evaluating the purpose of the tree(s) and proper tree selection for the intended site(s). This involves a little research.
Lindsey Purcell, Purdue urban forestry specialist (retired), and Kyle Daniel, Purdue nursery & landscape outreach specialist, authored the Purdue Extension publication, “Tree Selection for the ‘Un-natural’ Environment,” a title that describes the built environment for home landscapes and urban settings.
“Successful tree selection requires us to think backwards – beginning with the end in mind – to get the right tree in the right place…in the right way,” they said.
First, the Purdue specialists encouraged homeowners to determine why they are planting a tree. This includes its intended function in the landscape, the ornamental value, and the appropriateness of the species for the area.
Trees provide many landscape functions: providing shade, providing a natural screen from off-property sights, providing a windbreak, or serving as a landscape feature. Trees may not only provide this functional role but also provide an environmental or aesthetic value. “Well-placed shade trees can reduce cooling costs for the home or business, and increase pavement life,” they said.
Trees provide many ornamental values. Consider leaf color, texture, and/or flowers and fruits during the selection process. “Some species provide beautiful displays of color for short periods in the spring or fall,” they said. “Other species have foliage color displays that add interest year-round.” Additionally, do you want green foliage all year long in some parts of your landscape? Maybe you desire trees or shrubs that bear fruit or nuts, along with the benefits they bring to wildlife.
We should plant trees appropriate to our area of Indiana, and to the specific location in our landscape. This consideration includes the USDA Hardiness Zone rating (see https://planthardiness.ars.usda.gov/), whether the tree or shrub has invasive tendencies, and the specific characteristics of the intended planting site. “Select trees for the location by recognizing the appropriate species relative to hardiness, exposure, soil type, drainage, moisture requirements, and ornamental characteristics,” they said.
Your site may have a unique microclimate characteristic. “A sheltered planting site may support vegetation not normally adapted to a region, while a north-facing slope may be significantly cooler or windier than surrounding areas, limiting the survival potential of normally well-adapted plants,” they said.
The authors encouraged purchasing plants from a reputable source, with evidence of good care. “Select trees that have good branching structure and are free from defects or pests,” they said. “Good branch structure creates a healthy, stable, mature tree that is less likely to fail from splitting in wind and storms.” Trees with a single, central branch leader system are much stronger than trees with codominant branches, they said.
Consider native trees and other non-invasive, cultivated tree species that are well-adapted to home landscapes and urban settings. The publication lists native trees to consider for home and urban landscapes, as well as “utility-friendly” trees. “Native plants do not always guarantee sustainable landscaping nor resistance to insects or diseases,” they said. “Native plants suffer just as much from pests and decline, especially in the built environment.”
The authors encouraged species diversity. “Poor tree diversity in the past led to catastrophic results when there have been invasions by pests such as Dutch elm disease,” they said. “More currently, emerald ash borer and Asian long-horned beetles have destroyed urban trees.” Maples are a beloved tree species, but the authors indicate that maples are the most populous and over-planted tree species group.
As you consider the planting site, also visualize the eventual mature size and shape of the tree. This is a common oversight. “Consider mature size before planting,” they said. “Inspect the area around the tree-planting site for potential future conflicts with other natural habitats and especially overhead utilities.” Consider also the proximity to your house and other structures.
“Finally, be sure the tree provides you with the ornamental characteristics you want, such as overall appearance, flowering, fall color, fruit, winter interest with bark, or evergreen color,” they said. “Trees are important for their functional qualities, but they should complement the landscape and provide visual beauty as well.”
Find the publication referenced at www.edustore.purdue.edu. Search also at the site for a related video entitled, “Tree Planting Part 1: Choosing a Tree.”