How Glacial Till Soil Causes Shallow Tree Roots

How Glacial Till Soil Causes Shallow Tree Roots

Glacial till has long caused problems when it comes to growing plants in the Pacific Northwest. While native plants have adapted to it, imported trees and bushes often struggle to establish deep roots in this type of soil.

WHAT IS GLACIAL TILL SOIL?

Glacial till is an unsorted mix of silt, clay, gravel, sand and boulders created by erosion caused by the movement of glaciers. At least six times over the past two million years, the region was covered by ice sheets; the advancing and receding of these sheets pushed the till around the region. When the final ice sheet receded, a thick layer of till was left in some areas.

WHY GLACIAL TILL CAUSES SHALLOW ROOT SYSTEMS

Because of the sand, gravel and rocks, glacial till resists root penetration and doesn’t retain water well. This forces trees’ roots to grow outward instead of down which leads to shallow root systems. This can be a problem when storms hit because trees with shallow roots are more likely to be uprooted during strong winds. When planting trees, higher quality soil or organic materials can be added on top of the glacial till to encourage the roots to establish, but the roots will still remain shallow to avoid the till.

WHAT TO DO IF YOU’RE HAVING ISSUES WITH GLACIAL TILL

If you’ve ever tried digging into the ground on your property and discovered it was very rocky and sandy, you’re likely dealing with glacial till. There are some steps you can take to establish better soil, like adding organic material. Another consideration when dealing with this type of soil is the placement of trees. Because they are more likely to fall during a storm, you want to be strategic about where you are planting them and be aware that some already established trees may pose a threat to your home in high winds.