Healthy trees start with healthy roots, but what happens when the roots themselves become the problem? Girdling roots are a common yet often unnoticed issue in urban and suburban landscapes. They can silently strangle a tree from the inside out, leading to poor growth, decline, or even death if not addressed early.
Let’s take a closer look at what girdling roots are, how to spot them, and what to do if your tree is affected.
What Are Girdling Roots?
Girdling roots are roots that grow in a circular pattern around the trunk or root flare of a tree instead of extending outward into the soil. Over time, these encircling roots can compress the trunk and other roots, restricting the flow of water and nutrients.
Girdling roots can be caused by:
- Improper planting (especially planting too deep or in small containers)
- Compacted soils that prevent natural root expansion
- Trees left in their nursery containers too long before planting
- Mechanical barriers like curbs or sidewalks
Signs Your Tree May Have Girdling Roots
This condition often develops below the soil surface, but there are visible clues:
- A trunk that appears to go straight into the ground like a telephone pole (no visible root flare)
- Thinning canopy or reduced leaf size
- Early fall colour or leaf drop
- Dieback in the crown
- Cracks or seams in the bark
- Leaning or poor anchorage in wind
If your tree isn’t growing like it should, or seems stressed for no clear reason, it’s worth checking for girdling roots.
What Can Be Done About Girdling Roots?
The good news is that early detection can save your tree. Here’s what can be done:
- Inspection & Diagnosis
A certified arborist can gently excavate the soil around the base of the tree (called air spading or root collar excavation) to look for problematic roots. - Root Pruning
If girdling roots are found, they can often be removed or pruned with specialized tools. This procedure must be done carefully, removing too many roots or cutting too close to the trunk can harm the tree. - Soil Improvement
After addressing the girdling roots, improving the soil with organic matter or mulch can help prevent future issues and support healthy root regrowth. - Monitoring
Trees that have had girdling roots corrected should be monitored annually for signs of recovery or further issues.
Prevention Is the Best Medicine
Girdling roots are easier to prevent than to fix. Here are a few tips for homeowners:
- Make sure trees are planted at the correct depth, the root flare should always be visible above ground.
- Choose nursery stock with healthy, outward-growing roots.
- Avoid piling mulch against the trunk (“volcano mulching”), this can encourage roots to grow upward in search of oxygen.
- Use wide, shallow planting holes to encourage proper root spread.
Concerned About Girdling Roots?
If you suspect your tree may have girdling roots, or just want peace of mind, our team of ISA Certified Arborists can help. We use non-invasive diagnostic tools and industry best practices to assess and treat root issues before they become fatal.
