Selecting trees for deep rooting
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
I recently received a phone call from a person responsible for planting trees in a small local cemetery. The landscaper was interested in selecting deep-rooted trees to avoid development of extensive root systems that might interfere with gravesites. Unfortunately, there is relatively little information on selection of deep-rooting trees. Most of the information in this regard is based on avoidance of shallow-rooted trees that can damage sidewalks by growing underneath them.
The leading “problem children” for sidewalks are sweetgum, elms, ashes and maples. The common denominator for these trees is that they are adapted to bottomland or wet-site sites and tend to form extensive root systems. Conversely, trees from upland sites such as oaks, hickory, and beech tend to form tap-root or heart root systems and may be less likely to send roots into adjacent areas where they are unwanted. The caveat with recommending trees based on root habit is that soil conditions can trump the tree’s predisposition to form either spreading roots or a tap root. For example, studies have shown that eucalyptus trees grown on sandy sites will form a deep taproot while the same species grown on a poorly drained area will form an extensive root system. So the key, as always, is to know your site, know your trees and plant the right tree in the right place.