Myths and Misconceptions About Tree Roots: Setting the Record Straight

Most people have a vague understanding of the importance of a tree’s root system. They understand that roots absorb water from the ground and help to keep a tree standing upright, but few know much more than this. In fact, many are unfortunately misinformed about some of the major aspects of tree root biology.

We’ll try to help correct this below, as we look at a few of the most pervasive myths and misunderstandings regarding tree roots. This should help you understand your trees (and the things they need to stay healthy) much more effectively.

Myth #1: Tree roots penetrate deep into the ground to help anchor the tree.

Truth: While some trees do produce a tap root that primarily grows straight down into the earth, and some produce secondary “sinker roots” that grow down from the tree’s primary roots, tree roots anchor trees and keep them upright by growing out, rather than down. This allows them to “grip” a larger portion of the soil than if they simply used depth to keep a tree upright, and it is part of the reason that root systems extend so far from a tree’s trunk.

Myth #2: Tree roots grow to the edge of the canopy and then stop.

Truth: While many arborists and tree-care professionals rightly advise homeowners to do everything possible to protect the roots underneath a tree’s canopy, this does not mean that roots don’t extend beyond the canopy’s edge. In fact, many trees produce root systems with a diameter that greatly exceeds that of the canopy. To be sure, the bulk of the tree’s roots do usually occur within the boundaries of the canopy, and these roots do require special protection, but they often extend for much farther into the surrounding soil.

Myth #3: The most important roots of a tree are found deep underground.  

Truth: As explained earlier, some trees do produce roots that penetrate rather deeply into the ground. However, even these trees primarily rely on the roots in the upper portions of the soil. Typically, the most important roots for a given tree are all found in the top 12 to 24 inches of the soil. At this depth, the roots can obtain all of the things they need, including moisture and oxygen.

Myth #4: It doesn’t matter if a tree’s surface roots become damaged by lawn mowers or other equipment.   

Truth: Most of a tree’s root system grows in rather shallow soil. In fact, the most important roots typically grow between about 12 and 24 inches of depth. However, some trees produce roots that extend above the soil line. These types of roots often suffer damage from lawn mowers and other types of equipment, and many homeowners are under the impression that this type of damage isn’t harmful to the tree. In actuality, this type of damage can be very harmful to the tree, as it not only compromises a tree’s ability to anchor itself and absorb the water and nutrients it needs, but it also subjects the tree to pests and pathogens. This is why it is so important to place a layer of mulch above a tree’s root system.

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Don’t feel bad if you’ve fallen victim to some of the myths explained above. Many of these misunderstandings are surprisingly prevalent among the general public, as well as the occasional well-meaning, but misguided tree-care professional.

If you have any questions or concerns about the roots systems of your trees, don’t hesitate to reach out to your friends at Evergreen Arborist Consultants. We’ll send one of our ISA-certified arborists to your property to address your concerns and help ensure that your trees – and especially their roots – remain healthy and happy for a long time to come.