Prevent Girdling Roots to Avoid Long-Term Damage

Jeana Cadby
September 30, 2020

Girdling root systems can cause long term tree damage, dieback, and eventually tree death. Trees with weakened root systems due to girdling roots often go undiagnosed until it is too late. Issues that inevitably arise as a result of girdling roots cannot be overcome without addressing the problems under the surface.

Fortunately, girdling roots are preventable. Read on to find out more about prevention and avoid long-term damage, dieback, and falling trees.

The Root of the Problem

Girdling roots may be visible at soil level but are more likely hiding beneath the soil surface. Horizontal roots wrapped around the base of the tree grow larger every year and restrict the flow of water and nutrients, weakening the tree over time. Issues that arise from girdling roots can make it more difficult for trees to overcome transplant shock, environmental stresses, and disease.

Trees may develop girdling roots if planted too deeply or when too much mulch is applied to the base of the tree, burying the root collar. A buried root collar can also damage tree bark and make trees more susceptible to infection, disease, and root dieback. Properly placing trees in the right sized planting holes can help prevent girdling roots from forming.

Trees transplanted into holes with loose soil allows trees to settle, allowing roots to encircle the buried root collar. Holes with impervious soil, concrete, or other obstructions can force roots to grow circularly and against the tree trunk. As a general rule, the top of the root ball should be level with the ground, or 1-2” above soil level.

A ‘Flare’ for Landscaping

The root flare is the transition zone at the base of the tree, where the roots ‘flare’ out from the stem or trunk of the tree. Although not all trees have a distinct flare at the point where the roots begin to emerge from the trunk, using appropriate planting depth is critical to the long-term health and survival of the tree.

Abnormal trunk flare is often an indicator of girdled roots, and symptoms of girdling roots include late leaf flush, early leaf drop, dieback, and chlorosis. When left untreated, trees with girdling roots are prone to falling over or death.

Stocking Up

The best defense against girdling roots is prevention, as remediation efforts often include excavation or tree replacement, and the lasting damage on tree vigor due to girdling roots can be apparent for years. When plants are held in containers for too long or in the wrong sized pot, roots may begin to circle in the pot, leading the formation of circling roots.

Circling roots can cause the root mass to become dense, preventing healthy root growth and spread, and eventually weakening the root system. Some nursery-grown trees may also be placed too deep in their pots, making it all the more difficult to establish healthy trees during planting.

Prevent root girdling following these tips:

  • Ensure planting holes are wider than the root area.
  • Avoid planting in compacted soil, backfilling, or placing too much soil or mulch over the roots.
  • Address issues at the time of transplanting; loosen, reorient, or prune circling roots.
  • Use healthy tree stock free of circling roots, buried collars, or other controllable quality issues.

Conclusion

Girdling roots can be immensely damaging to the health and longevity of landscaping trees but are preventable with good planting practices. Buried root collar tissue and girdling root formation is associated with burying trees too deep under the soil surface. Use healthy trees from the nursery, avoid root bound or spiraling roots, plant in the right conditions, and most importantly, at the proper depth.

At Garden Gate, we do our best to transplant trees at the right soil level, and ensure that we prevent root circling by cutting roots at transplant time.

The only next step is making sure you plant your trees at the right level, and cutting any circling at the time of planting in your landscape.

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