Artificial Grass Around Tree Roots Without Killing the Tree

Why a big tree changes the job

Plenty of older Australian backyards have a mature gum or a big native sitting right where the lawn gave up, because the tree wins every fight for water and light.

The trouble is that a standard turf install is hard on trees. Our step-by-step installation guide has you strip 70 to 100mm of soil, spread road base and run a plate compactor over it in two directions. Across open lawn that is exactly right. Across a tree's root zone it can mean cutting feeder roots, squeezing the air out of the soil and changing how water reaches the roots, all in one weekend. The decline tends to show up seasons later as thinning canopy and dieback, which is why it catches people out. You can still have turf and a healthy tree by laying the ground under it differently.

Where the roots are

Most of a tree's fine feeder roots sit in the top part of the soil, and they spread a long way sideways, often well past the edge of the canopy. Gums and paperbarks in particular tend to run roots close to the surface over a wide area.

Arborists in Australia work out how much ground to protect using AS 4970, the Australian Standard for protecting trees on development sites. The basic method is simple enough to do with a tape measure:

• Measure the trunk diameter at 1.4 metres above the ground (this is called DBH).
• Multiply it by 12. That gives you the radius of the protected zone, measured out from the centre of the trunk.
• Under the standard the zone is never less than 2 metres or more than 15 metres in radius.

So a gum with a 50cm trunk gets a 6 metre radius, which can cover half a suburban backyard. The 2025 revision of the standard renamed this area the Notional Root Zone (it was the Tree Protection Zone), but the 12 times DBH calculation stayed the same. Inside it sits a smaller Structural Root Zone around the trunk, where the big anchoring roots live. Digging there is the one thing to avoid completely.

A backyard turf job is not a development site, and nobody is going to inspect your yard against AS 4970. It is still the best available yardstick for how far out the roots matter. Under the 2025 version, disturbing up to about 10% of that zone (outside the structural roots) counts as a minor encroachment. Anything more is the point where an arborist's advice earns its fee.

Check whether the tree is protected

Before you touch the ground, find out whether your council protects the tree. Many Australian councils have tree protection local laws or planning overlays that cover significant trees, and some require a permit for works inside a protected tree's root zone, including paving, trenching or changing ground levels. Some also require a permit to cut more than a small share of a tree's roots. The rules vary between councils, so check with yours first. Our council approval guide covers the wider question of when turf itself needs sign-off.

Three ways to handle the root zone

There are three sensible approaches, and many yards combine them.

Approach	What you do inside the root zone	Good for	Trade-offs
Mulch ring, no turf	Leave a circle of mulch around the trunk and stop the turf at its edge	Big or protected trees, trees already under stress	Less lawn, one more edge to finish neatly
Shallow no-dig lay	No excavation, a thin permeable layer on top of the existing soil, light hand tamping	Most mature trees where you want turf close in	Surface is less perfectly flat, lumps from roots may show
Standard base	Full dig, road base and plate compactor	Only the ground outside the root zone	Unsuitable within the tree's root zone

Mulch ring

The simplest option is to stop the turf short of the trunk and leave a ring of organic mulch. Taking it out towards the drip line is better still if you can spare the space. The tree keeps loose, breathing soil where its roots are busiest, rain soaks straight in, and you get a clear place to rake leaves into. Edge the ring with timber, steel or a row of pavers so the turf has something firm to butt against. On a big tree this is usually the smartest answer.

Shallow no-dig lay

Where you want turf closer to the trunk, skip the excavation inside the root zone. Remove the old grass and weeds by hand or with a spray rather than a turf cutter, fill low spots with a thin layer of crusher dust or decomposed granite laid on top of the existing soil, and firm it with a hand tamper instead of the plate compactor. Keep the build-up as thin as you can. Piling a thick layer of fill over roots is its own problem, because it can starve them of air just like compaction does.

Expect the finish to be a little less flat, since turf follows the roots underneath. A gently rolling patch under a tree looks natural, and it beats losing the tree.

Standard base, outside the zone

Past the root zone, build the base properly, and taper the depth over a metre or so where it meets the shallow lay to avoid a step.

Keeping water and air getting through

This is where porosity matters most. Tree roots need both water and oxygen, so every layer between the sky and the soil should let both through.

• Use a woven or non-woven geotextile weed membrane. These are permeable. Never lay builder's plastic, pond liner or any solid sheet, even as a weed barrier.
• Turf backing matters too. Our range uses a punch-hole backing, and APT's brochure quotes drainage of up to around 2,000mm per hour in the manufacturer's testing.
• Keep the base fall gentle and avoid directing all the runoff away from the tree. A yard graded hard towards a drain can leave a tree drier than it was before.

The tree was probably drinking from the old lawn's sprinkler, which usually stops once turf goes in. During dry spells, give the tree a deep soak around the mulch ring or through the turf itself, especially in the first summer after the install.

Pinning, cutting and joining around roots

Turf pins are long galvanised nails, and in a root zone they can go straight into a root. If a pin hits something solid, pull it and move it rather than hammering through. In the tightest spots, joining tape and outdoor adhesive along the seams and a firm edge at the mulch ring can hold the turf with fewer pins.

Don't cut roots to get a flatter surface. Losing a few small ones is usually fine, but anything thick enough to be structural should stay put unless an arborist says otherwise. Lay the turf over it instead.

Around the trunk or mulch ring, let the turf relax in the sun first, then cut the curve in small bites with a sharp blade. On ordering, our turf comes in fixed lengths (commonly 5m, 10m, 15m or a full 20m roll, depending on the product) at a 3.71m width, and a shorter length carries a cutting fee. For a yard with a tree in it, plan your runs so a join lands away from the trunk if you can, and expect some offcut from the curve. Our yard measuring guide shows how to work out lengths and joins.

Choosing turf for under a tree

Under a tree, the turf's main jobs are handling leaf drop, shade and whatever falls from above. Gums shed leaves, bark, twigs and gumnuts all year, and a shorter, denser pile is easier to blow or rake clean. Our pile height guide covers the trade-offs, and the autumn leaf litter guide covers keeping the surface clean.

A hard-wearing option like SynRye, which uses nylon fibres that SYNLawn describes as the most durable landscaping turf in its range, suits a spot that gets raked a lot. If you would rather keep the budget down under the tree, Summer 30 Super sits at the lower end of our range. Both product pages have a length and quantity calculator, so you can see current pricing on the product page for your actual runs.

Frequently asked questions

Will artificial grass kill my tree?

The turf itself is unlikely to harm the tree. The damage usually comes from the install: digging out the soil, cutting roots and compacting a base across the root zone. Skip the excavation and heavy compaction under the tree, use permeable layers, and keep up deep watering in dry spells.

How close to a tree trunk can I lay artificial grass?

There is no fixed rule, but a common approach is to leave a mulch ring around the trunk and stop the turf at its edge. For a guide to how far the roots matter, multiply the trunk diameter at 1.4 metres by 12 to get the root zone radius arborists use under AS 4970. Avoid any digging close to the trunk, where the structural roots are.

Can I lay artificial grass over exposed tree roots?

Yes, as long as you lay over them rather than cutting them out. Build a thin layer of crusher dust or decomposed granite around the roots, firm it by hand and accept that the finished surface will follow their shape a little. Pin away from roots and move any pin that strikes something solid.

Do I need an arborist before laying turf near a tree?

For a small tree and a mulch ring, most people go ahead without one. It is worth paying for advice if the tree is large, already looks stressed, or might be protected by your council, or if your plans involve cutting roots or disturbing more than a small share of the root zone.