How to Landscape Around Existing Tree Roots Without Damaging the Tree

Paving Adelaide existing trees can make a garden feel established, shady and mature, but landscaping around them requires more care than working in an empty garden bed. Tree roots may spread much farther than the visible trunk and can sit surprisingly close to the soil surface.

This creates a challenge when you want to add garden beds, mulch, paving, edging or new plants around an established tree. Digging through roots, changing soil levels or compacting the ground with machinery can affect the tree’s health and stability, sometimes without obvious symptoms appearing immediately.

The safest approach is to design around the existing root system rather than trying to reshape it. That means limiting excavation, protecting the soil around the tree, avoiding unnecessary grade changes and choosing landscaping materials that allow air and water to reach the root zone.

Why Existing Tree Roots Need Protection

A tree’s root system is not simply a collection of large roots directly beneath the trunk. Many important roots are relatively fine and are responsible for absorbing water and nutrients.

The area that needs protection can therefore extend well beyond the visible base of the tree. Construction and landscaping can damage trees through root severing, soil compaction, changes in drainage and adding or removing soil around the roots. These impacts may contribute to decline long after the landscaping work has been completed.

This is why a landscaping project that looks harmless above ground can still create problems below ground.

For example, installing a new garden path might involve:

Excavating the existing soil.
Cutting through roots.
Compacting the remaining soil.
Installing a non-permeable surface.
Changing how rainfall reaches the root zone.

The finished path may look excellent while the tree is left with a significantly altered growing environment.

Start by Identifying the Root Zone

Before deciding where to dig, pave or plant, identify the area that needs to remain as undisturbed as possible.

In Australia, AS 4970:2025 Protection of Trees on Development Sites provides current guidance for retaining and protecting trees during development. The 2025 edition uses concepts including the Notional Root Zone (NRZ), Tree Protection Zone (TPZ) and Structural Root Zone (SRZ) to assess areas requiring protection.

For a simple residential landscaping project, you may not need a formal arboricultural assessment for every tree. However, the principle is useful: the closer your proposed work is to an established tree, the more carefully it should be designed.

Look for:

Exposed surface roots
Areas where roots have lifted existing paving
The approximate canopy spread
Soil changes around the trunk
Existing garden beds
Previous excavation or construction
Signs of tree stress or decline

If substantial excavation, retaining walls, paving or earthworks are planned close to a mature tree, a qualified arborist can assess the tree and recommend appropriate protection measures.

Avoid Cutting Tree Roots Where Possible

One of the biggest mistakes when landscaping around existing trees is treating roots as an obstruction.

If a root appears where you want to install an edge or planting hole, the temptation is to cut it and continue. That can be particularly problematic when larger structural roots are involved.

TreeNet’s guidance on trees in hard landscapes notes that root pruning can have a significant negative effect on tree health and stability and should be treated as a last-resort measure under expert supervision.

Instead of cutting a root, consider changing the design.

For example, you could:

Move the garden edge slightly.
Change the shape of a planting bed.
Use a curved path instead of a straight one.
Select plants that require smaller planting holes.
Use surface treatments that do not require deep excavation.
Bridge over roots where appropriate.
Use a raised or suspended construction method for certain hardscape applications.

A few design changes before construction can be far easier than trying to repair a damaged tree later.

Avoid Raising or Lowering Soil Levels Around the Tree

Changing the level of soil around an established tree can be just as problematic as digging into the root zone.

Adding a substantial amount of soil can reduce the availability of oxygen around roots and alter water movement. Removing soil can expose roots to drying, temperature changes and physical damage.

Australian tree-protection guidance specifically recognises grade changes and soil compaction as potential sources of root damage.

This is particularly relevant when building a new lawn, garden bed or retaining wall around an established tree.

If the existing soil level is working, keep it as close to its original level as practical.

What If the Existing Roots Are Already Exposed?

Do not automatically bury exposed roots beneath a deep layer of topsoil.

First determine why the roots are exposed. Erosion, previous landscaping, soil movement or natural growth can all be involved.

A tree-sensitive solution may involve mulch or another suitable surface treatment rather than substantial soil being placed over the roots.

If major roots are exposed or the tree appears unstable, seek arboricultural advice before changing the area.

Use Mulch Instead of Digging Where Appropriate

Mulch is often one of the simplest landscaping solutions around established trees because it can improve the surface environment without requiring extensive excavation.

Organic mulch can help reduce evaporation, moderate soil temperature, suppress weeds and reduce soil compaction caused by mowing or foot traffic.

However, mulch should not be piled against the trunk.

Create a clear area around the trunk and allow the visible root flare to remain uncovered. Excessively deep mulch can reduce oxygen availability, keep poorly drained soil too wet and encourage roots to grow into the mulch layer.

A broad, relatively shallow mulch area is generally preferable to creating a tall mound around the tree.

Choose Plants That Work With Existing Roots

Underplanting around an established tree can be attractive, but it needs to be approached carefully.

Large plants that require deep planting holes may disturb roots. Dense or highly competitive plants may also compete for water and nutrients.

Instead, consider:

Smaller groundcovers
Shade-tolerant plants
Shallow-rooted ornamental plants where appropriate
Plants suited to the local soil and climate
Groups of smaller plants rather than a few large specimens

Avoid randomly digging dozens of planting holes through an established root system.

Where roots are already close to the surface, it may be better to use fewer plants and rely on mulch to provide a finished appearance.

The specific plants should be selected according to the tree species, available sunlight, soil conditions and local climate.

How to Landscape Around Roots Without Digging

There are several ways to create an attractive garden without repeatedly disturbing the soil.

Use Curved Garden Edging

A curved garden edge can be designed around visible roots rather than cutting through them.

This also tends to look more natural than forcing a perfectly straight border around an irregular mature tree.

Create a Mulched Tree Island

A broad mulched area surrounding the tree can become a deliberate landscape feature rather than an area that looks unfinished.

You can define the outer edge with low-profile edging positioned away from major roots.

Use No-Dig or Low-Excavation Surfaces

Where a path must pass near an existing tree, a low-excavation or no-dig approach may reduce disturbance compared with traditional paving construction.

TreeNet’s guidance for trees in hard landscapes identifies options such as bridging over roots and other solutions that reduce the need to remove or damage roots.

The correct construction method depends on the tree, root distribution, surface requirements and expected loads.

Be Careful With Paving Around Existing Trees

Paving can create two separate problems.

The first is construction damage. Preparing a traditional paved surface may require excavation and compaction within the root zone.

The second is the long-term effect of changing the soil surface. Impermeable paving can reduce the amount of water and air reaching the soil.

Where paving is necessary, consider whether the design can:

Move farther away from the trunk
Follow the existing ground level
Use permeable or open-jointed materials where suitable
Reduce excavation
Bridge over sensitive roots
Provide a larger unpaved area around the tree

TreeNet’s guidance includes techniques such as flexible surfacing, bridging and load-bearing systems designed around existing roots where hard landscapes must coexist with established trees.

Protect the Tree During Landscaping Work

Even if the final design is tree-friendly, construction activity itself can cause damage.

Do not allow:

Excavators to operate directly over the root zone without an appropriate protection plan
Heavy vehicles to repeatedly drive over the soil
Building materials to be stored around the tree
Concrete washout to occur near the roots
Soil or rubble to be piled against the trunk
Trenches to be dug casually through the root zone

Australian local-government guidance based on AS 4970:2025 commonly uses a Tree Protection Zone to restrict activities that could damage retained trees, including soil compaction, excavation and material storage.

For a larger landscaping project, tree protection should be established before work begins rather than after damage has already occurred.

When Should You Call an Arborist?

Professional arboricultural advice is particularly worthwhile when landscaping involves:

A large mature tree
Major exposed roots
Excavation close to the trunk
Retaining walls
Significant soil-level changes
New driveways or paving
Drainage works
Construction access through the root zone
A tree with existing signs of decline
Roots affecting structures or major hard surfaces

An arborist can assess the tree, identify sensitive root areas and recommend construction methods that reduce the likelihood of damage.

This is especially relevant where planning or development approval requires tree-protection documentation. Australian councils can impose project-specific tree protection requirements, so local rules should be checked rather than assuming the same requirements apply everywhere.

Common Mistakes to Avoid

Cutting roots because they are in the way

Change the design before cutting established roots. Larger roots can contribute to tree stability and health.

Building a raised garden bed around the trunk

A raised bed can unintentionally bury the root zone and trunk flare beneath additional soil. Keep existing soil levels in mind.

Creating a mulch volcano

Piling mulch against the trunk can keep bark excessively wet and create other tree-health problems.

Digging dozens of planting holes

A large number of small excavations can still cause substantial root disturbance. Work with the existing root pattern.

Driving machinery over the root zone

Compaction can reduce soil pore space, restrict water movement and reduce oxygen available to roots.

Treating every visible root as a problem

Surface roots are not necessarily something that needs to be removed. Often, the landscape can be designed around them.

Assuming the same tree rules apply everywhere

Tree-protection requirements can vary between councils and project types. Check the applicable local requirements before starting regulated work.

Frequently Asked Questions

Can I put mulch over exposed tree roots?

Mulch can be suitable for protecting the soil around tree roots, but it should not be piled deeply over the root flare or against the trunk. Excessively deep mulch can reduce oxygen availability and create moisture problems.

Can I plant flowers around the roots of an established tree?

Yes, but choose plants carefully and minimise excavation. Small plants that require shallow planting may be more appropriate than large specimens requiring deep holes.

Should I cut tree roots that are sticking above the soil?

Do not routinely cut exposed roots yourself. Larger roots may contribute to tree stability, and cutting them can cause significant damage. An arborist can determine whether intervention is appropriate.

Can I build paving over tree roots?

Sometimes, but conventional paving may require excavation and compaction that can damage roots. Root-sensitive construction methods, permeable surfaces or bridging solutions may be appropriate depending on the site.

How far should landscaping be kept from an existing tree?

There is no single distance suitable for every tree. The required protection area depends on the tree, its size, condition, root system and proposed work. For Australian development projects, the current AS 4970:2025 framework provides a basis for assessing root protection areas.

What should I do if landscaping has already damaged the roots?

Avoid further disturbance and have the tree assessed by a qualified arborist, particularly if major roots have been severed, soil levels have changed significantly or heavy compaction has occurred.

Final Thoughts

The best way to landscape around existing tree roots is to work with the tree rather than against it.

Instead of cutting roots, burying them under large amounts of soil or excavating the entire area, design the garden around the existing root system. Mulched garden beds, carefully selected underplanting, curved edging and low-disturbance pathways can all create an attractive result while keeping the tree’s growing environment intact.

For more involved projects involving paving, drainage, retaining walls or significant earthworks, getting an arborist involved before construction can help identify potential problems early. A little planning at the design stage can prevent root damage that may take years to become visible.

If you are planning landscaping around a mature tree, consider having the site assessed before excavation begins. This allows the garden design, materials and construction approach to be selected around the tree rather than trying to repair the damage afterwards.