Stem Girdling Roots

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Circling & Stem Girdling Roots

What happens when we plant our new tree or shrub in a hole that’s the size of the pot we brought home from the store? What happens if we don’t realign the roots? If the roots fill and are circling within the pot then placed in the ground without realignment, they will continue that circling pattern in the ground.

As both the tree and its roots mature, these circling roots may cut into the tree bark and interfere with the transportation of water and nutrients, in effect strangling the tree.

We plant young trees, envisioning them at their full mature form and peak landscape value. A mature tree girdled by its roots is a significant and easily avoidable loss to the landscape vision and home value. Two photos show examples of trees planted without realignment of the roots. The trees were removed when a Master Gardener purchased a 10 year old home and redesigned the landscape plan.

Stem Girdling Roots

stemgirdlingThis photo shows an example of stem girdling roots. This is a semi-dwarf pine 8 to 10 inches in diameter at the base, about 10 feet tall and about 10 to 11 years old. Roots that were circling in the pot and not stretched out at planting continued to grow in that circular pattern. As both the tree and its roots mature, the roots can cut into the tree bark and begin to interfere with the transportation of water and nutrients, over time strangling the tree.

There are two roots encircling the base, originally just below ground level (you can see the darker soil line just above the encircling roots. In addition to the girdling root, it appears to be planted too deep). The largest of the girdling roots went around at least half of the base before it headed off to the right in the photo. Another smaller root is encircling from the opposite direction and actually crosses over the larger one, seen in the lower right of the photo. You can see how these two roots restricted the tree’s girth.

When this tree was planted, the roots were not spread to radiate out from the tree. This tree probably was transplanted from a one gallon pot, as the roots are tight against its base. If a root has started going around the pot and is too large to bend away from the tree’s base at planting time, it should be cut off to allow healthy roots to grow.

Circling Roots

rootboundtreeThis photo shows how roots that are not stretched out away from the trunk in a planting hole continue to grow in the direction they grew in the pot. It is a dwarf pine with a 6 to 8 inch diameter trunk and perhaps 6 to 8 feet tall. It had been pruned in a multi-branching pattern, otherwise would have been taller. Most likely it was 10 or 11 years old.

We see the trunk of this tree filling the lower left corner of the photo, with the roots center top. (We’re looking at the tree top-down.) When the new homeowners removed the tree because it was visually in the wrong place, they realized what a struggle the tree had, with so many of it’s roots running around the base. This condition likely would have reduced the long term vigor of this tree.

The tree probably was purchased in a three gallon container and the roots had been just going around and around inside the pot, making a jumble. When initially planted, the roots were not pulled out away from their encircling pattern. Had it been too difficult to straighten them out in a radiating pattern, they could have been cut. Eventually a few deeper roots (furthest away in the photo) finally were able to head out as they should, where they could get adequate water and nutrients.

Roots radiating out from a tree or shrub also make it more stable and better able to withstand winds.

Avoid this potential damage to your investment in your landscape and home value. Learn proper planting techniques.

These examples and information are provided by WSU Chelan County, WA Master Gardener Mary Fran McClure, December, 2009.

Washington State University