Too much soil around the base of the tree can compromise the long-term health of the tree. This can be caused by several factors. Many times trees are planted too deep in the ground. Planting a tree too deep can greatly influence how it grows, and how healthy it will be. Often bark dust or soil is added around the base of the tree. This can result in excess soil pressing against the lower trunk.
Soil and bark dust against the lower portion of the trunk will hold moisture there, and increase the potential for fungus, rot, or water damage. These negative influencers can travel up the stem, as well as down into the root system and compromise the tree.
Girdling roots is another reason to justify root excavation. Girdling roots is a common issue caused by the containers the trees were grown in forcing the roots to grow improperly. If a tree is left in a pot, waiting to be sold in a nursery for long enough, it will outgrow its pot. In a perfect world, a tree that is at risk for outgrowing its container will be given a new container before it grows too large. Unfortunately, most of the time, trees are left in their containers too long.
What ends up happening is the root structure of the tree will grow in a swirl pattern around the inside of the pot. The root structure will become so large and so overgrown within its small pot that it influences the large structural roots. If a tree that has been growing in such a way is planted without first taking into account these structural root issues, the outcome can be disastrous. Sometimes these large roots will grow into the stem or trunk of the tree and cause damage leading to rot below the ground. Other times the tree will be apparently healthy for decades until a windstorm when the tree comes crashing down. For this reason, we recommend you follow our tree planting guidelines or consult with us before planting a tree in your yard.
We aim to help our community avoid common tree and shrub planting mistakes so that they can help to make Vancouver, WA, and Portland, OR a more beautiful place to live. When you are getting ready to plant a new tree take note of where the trunk hits the soil in the pot and aim to keep that spot at ground level. Make sure not to cover the trunk with excess dirt and avoid planting the base of the tree too high. Trees are not meant to be replanted, so they rely on us to make the appropriate corrections when we are replanting them. A tree cannot correct where it lies in the soil, so doing the job right the first time is critically important.