Evaluate Your Site

A Guide to Site Analysis for Street Tree Plantings

Tree species vary considerably in their minimum requirements for rooting volume, soil pH, drainage, etc. A site evaluation will allow you to choose the very best trees for a given location. Without a site evaluation, communities often choose a tree species that will handle the worst possible site conditions as a safeguard against tree failure. The result of this practice is the overuse of a few highly tolerant “bread and butter” species, such as Bradford pears. These few species are not only monotonous, but can create catastrophic problems when a new pest arrives, or when problems, such as poor branching structure, are identified. It is good practice to always seek to diversify the tree species composition of a community. A good site evaluation is an essential tool in species diversification.

A thorough site evaluation should tell you how well a proposed planting site will be able to support street trees and what specific site limitations are. The Tree Selector’s Site Evaluation Form will guide you through this process. After the site evaluation is complete, select appropriate species and cultivars. The specific site for each tree should be considered to make sure a plant selection is made that will thrive in that spot.

Some site improvement can be made in many cases. You may need to Modify Your Site with subsoiling, tilling, grading, drainage, soil amendments, soil replacement, or other site preparations. Plants should then be selected that can tolerate the current or improved site conditions. Adapting the planting design to counteract site problems and better accommodate trees can also relieve some site limitations. Careful coordination of site conditions, tree selection and design adaptation will improve success.

The Virginia Urban Street Tree Selector Virginia Tech Forestry Department