Tree Roots

To control invasive tree roots one must first understand something
about them. This page will present a simplified overview of tree roots.

The first thing to know about tree roots is where they are. Most trees have a shallow roots system that extends up to twice the height of the tree. Roots tend to be no more then 24 inches deep. The tree roots do not grow by seeking nutrients or water. Tree roots grow where conditions allow them to grow. If conditions are good all around the tree the roots may spread out evenly. If conditions are good on only one side">

Tree Roots To control invasive tree roots one must first understand something about them. This page will present a simplified overview of tree roots. The first thing to know about tree roots is where they are. Most trees have a shallow roots system that extends up to twice the height of the tree. Roots tend to be no more then 24 inches deep. The tree roots do not grow by seeking nutrients or water. Tree roots grow where conditions allow them to grow. If conditions are good all around the tree the roots may spread out evenly. If conditions are good on only one side, more roots will develop in that area. When working with tree roots it is important to understand the basic types of roots. Each type of root serves a different function. Starting at the base of the tree trunk you will find the stump. Structural roots are large woody roots that extend from the base of the stump. They provide the structural support for the tree. Structural roots also transport water and nutrients up the tree as well as carbohydrates down to the roots. Because of there size and importance to the tree damage to these roots should be avoided if possible. Transport roots are just what the name implies. These roots are woody roots that transport water and nutrients from feeder roots to Structural roots. They also transport carbohydrates from the Structural roots to the feeder roots. They tend to range from a pencil in size up to a couple of inches. Transport roots are mostly found between 6 inches and 24 inches in the ground. Damage to these roots can cause less impact then damage to structural roots but it can still take several years for a tree to replace damaged Transport roots.   The roots that does most of the work is the Feeder root. These are non-woody roots that absorb water and nutrients. Only the tips of the feeder roots can absorb water and nutrients. They are not a permanent root, but die and are replaced. Many trees will replace around 60 percent of there feeder roots over the course of a year. The Feeder roots grow up from the Transport roots. Most of the Feeder roots will be between the leaflitter layer to 6 inches deep. Feeder roots take in water and nutrients and send it to the Transport roots. Carbohydrates are transported from the Transport roots to the feeder roots.   So why are tree roots invasive? Most soils trees are growing in soil containing 1 to 5 percent organic matter. My soil mix I use for my plants is rich in organic matter. It can have from 5 to 10 percent organic matter. Trees and plants such as Hosta  like the same rich soil high in organic matter. When soil is amended around trees for shade loving plants, the tree will quickly grow numerous feeder roots to take advantage of the available nutrients. There may have been no Feeder roots when you made your plant bed, but because of the ideal conditions you have created, tree roots will quickly grow into this rich area. A transport root will grow under your new bed creating Feeder roots that could choke the roots of the plants recently put in the bed. Some trees such as Willow can invade a plant bed in a matter of weeks.  Next