Grass Tree Harvesting Perth: How We Lifted 50 Xanthorrhoea in One Job

A client needed to relocate approximately 50 Australian grass trees (Xanthorrhoea australis, commonly called grass trees or black boys) from a development site before ground-breaking. The trees ranged from smaller specimens of around 1m to larger established plants with trunks over 1.5m tall and root systems that had been in the ground for decades.

Grass trees grow extremely slowly - a trunk height of one metre can represent 50 to 100 years of growth. Losing a tree due to poor extraction technique is not a small thing. The client had the appropriate approvals in place and needed the trees extracted in a way that gave them the best possible chance of survival at their new location.

This was not a standard earthmoving job. It required careful machine control, a good eye for root depth, and an operator who could adjust technique from tree to tree rather than applying the same approach to all 50.

Step 1: Assessing Each Tree Before Digging

Not all 50 trees were the same size or in the same ground conditions. Before starting the first trench, the crew walked the site and identified which trees had deep-set trunks, which were sitting in harder ground and which had neighbouring roots or obstacles that would complicate the lift.

Step 2: Trenching Around the Root Ball

The trench went in around the perimeter of the root ball - roughly 400-600mm out from the trunk depending on tree size - and down approximately 600-800mm. The goal was to sever the outer roots cleanly rather than tear them. The PC55 bucket was used at low crowd force to avoid compressing and dragging the trench wall into the root system.

For the larger specimens, the trench ran deeper - some root balls required going to 900mm before the main anchoring roots could be freed. Rushing that step and pulling too early is the main way you lose a grass tree in extraction.

Step 3: Freeing the Base and Lifting

Once the trench was complete and the outer roots were clear, the bucket was worked carefully under the root ball to free the base from the subsoil. The lift from the PC55 was slow and even - a jerky or uneven pull at this stage twists the root ball and can snap the trunk at the base, which kills the tree.

1. 01

   Walk the Site

   Assess each tree for trunk height, root spread and ground conditions before any digging starts.

2. 02

   Trench the Perimeter

   Cut a clean trench around the root ball, 400-600mm clear of the trunk, at low crowd force to sever roots without tearing.

3. 03

   Trench to Depth

   Go deep enough to free the anchoring roots - for larger trees this means 800-900mm. Do not rush this step.

4. 04

   Free the Base

   Work the bucket carefully under the root ball to separate it from the subsoil before attempting the lift.

5. 05

   Controlled Lift

   Lift slowly and evenly. A twisting or jerky lift at this point breaks the trunk at the base and the tree does not recover.

6. 06

   Load and Move

   Transfer the root ball to the transport vehicle or temporary holding area without letting it drop or tip sharply.

When you multiply half a tonne per tree by 50 trees, you are looking at roughly 25 tonnes of root balls moved across a single job. That is a significant excavation task even before you account for the precision required on each individual extraction.

Why the PC55 Was the Right Machine

The PC138 13.8t would have been too large and would have made the fine control required on each extraction harder to achieve. The PC18 1.8t mini lacked the reach and lifting capacity for the bigger root balls. The PC55 5.5t sits in the middle - enough power to lift a heavy root ball cleanly, precise enough to work close to a trunk without damaging it.

Being Komatsu-trained matters on a job like this. The PC55's hydraulic controls were operated at partial throttle for most extractions - high RPM and fast bucket movement is exactly wrong for grass tree lifting. Knowing the machine's control range and working in the lower part of it is an operator skill, not a machine spec.

Most plant hire jobs are about moving dirt efficiently. Grass tree harvesting is about moving living organisms with a root system that has been in the ground for potentially a century. The patience required is different from a standard dig.

“The first few trees took longer than expected while we worked out the right trench depth for the root systems we were dealing with. By tree ten, the team had the rhythm and we picked up the pace significantly. That kind of job teaches you to read the ground and the plant together.”

Plant Hire Perth

• Machine selection matters - mid-size gave control without sacrificing capacity
• Operator experience with the full throttle range of the machine is critical
• Adapting technique tree by tree is faster than applying one method to all
• The trench depth step is where most extractions succeed or fail
• Working with living plant material requires patience standard earthmoving does not

Xanthorrhoea australis is a long-lived, slow-growing native plant that takes decades to reach the sizes commonly seen on Perth development lots. A specimen with a 1m trunk has been growing since before most of the suburb around it existed. That is irreplaceable habitat value and significant ecological age packed into a single plant.

From a practical development standpoint, mature grass trees attract premium prices in the nursery and landscape market. Developers who preserve and relocate them rather than clearing them outright can often recoup meaningful value from the transplanted stock. The economics of careful extraction, when done correctly, often stack up clearly against losing the trees altogether.

Ecological and Landscape Value

Grass trees flower prolifically after fire or disturbance, producing long flower spikes that attract honeyeaters and other native fauna. In revegetation and native garden settings, a transplanted mature specimen creates instant visual impact that a tube-stock plant will not achieve for 20 to 30 years. That alone justifies the care taken in extraction.

• Mature specimens can represent 50 to 100 years of undisturbed growth
• Transplanted grass trees are in demand for revegetation and high-end landscaping
• Flower spikes attract native birds and insects - significant biodiversity value
• A living specimen moved correctly outperforms tube stock planted for years in one site visit
• DBCA translocation permits are required before any extraction begins

Grass tree survival after transplanting comes down to four factors: root ball integrity at extraction, how long the plant spends out of the ground, the quality of planting at the new site, and aftercare in the first wet season. The extraction itself is only the first variable, but it is the one that determines what all the others have to work with.

Root Ball Integrity

A root ball that was trenched cleanly and lifted evenly arrives at the new site with its fibrous root mass largely intact. A root ball that was torn, dropped or twisted loses much of that mass, and the tree has to regenerate root structure from a stressed starting point. Clean extraction is not just an aesthetic goal - it is the survival mechanism.

Time Out of the Ground

Grass trees are relatively resilient compared to many natives, but extended time out of the ground stresses any plant. On the 50-tree job, trees were moved directly from extraction to transport and replanted the same day where possible. Where staging was required, root balls were kept in shade and watered to prevent desiccation.

Planting Depth and Aftercare

Grass trees should be planted at the same depth they grew at the source site. Burying the trunk crown invites crown rot. Planting too shallow leaves the root ball exposed. Deep watering in the first two wet seasons and mulching around the base (not touching the trunk) gives the best chance of establishment.

Of the six steps in a grass tree extraction, the trench is where most jobs are decided. A correctly placed trench at the right depth severs the outer roots cleanly, leaves the root ball coherent and makes the lift straightforward. A trench that goes too close to the trunk, cuts at the wrong angle or stops short of the anchoring root depth creates problems that cannot be fixed at the lift stage.

Trench Placement: The 400-600mm Rule

For most Xanthorrhoea specimens in Perth, the trench perimeter sits 400-600mm out from the trunk. Smaller trees go closer to 400mm; larger, older specimens with wider root spread may require 600-700mm to avoid cutting through the main structural roots. Going too tight saves a little time but risks cutting the roots the tree needs most.

Trench Depth and Perth Soil Types

Sandy Perth soils allow roots to run deeper than compacted clay or limestone-rich ground. On sandy sites we typically trench to 700-900mm to find and free the anchoring roots. On harder ground, 600-700mm is often sufficient because root penetration is shallower. Reading the soil type before you start is part of the site assessment.

Low Crowd Force: What It Means in Practice

Crowd force is the inward curl pressure of the excavator bucket. On a standard earthmoving job you use full crowd to rip through material quickly. On a grass tree trench, high crowd force compresses the trench wall into the root system rather than slicing cleanly past it. Running the PC55 at reduced crowd force - around 30-40% of maximum - gives clean cuts and does not pack the root ball.

The extraction site itself requires attention after the trees come out. Each grass tree leaves a 400-900mm deep void in the ground surface. On a development site heading to earthworks, those voids are backfilled and compacted in the normal course of grading. On a revegetation site, they are filled with topsoil and native seed mix.

Spoil Management on Grass Tree Sites

The material extracted during trenching is typically sandy loam or sandy clay, depending on where in Perth the site sits. On our 50-tree job, the spoil was stockpiled on site for reuse in backfilling the voids after the client's ground-breaking work was complete. In cases where the spoil is not wanted, our 8t tipper handles cartage.

Can a Single Machine Do Both the Extraction and the Site Work?

On most jobs, yes. The PC55 we used for the grass tree harvesting on this job is the same machine that would handle subsequent site cuts, pad preparation or drainage trenching on the same lot. Mobilising a machine for both tasks on the same site is worth discussing when you call - it often makes more sense to schedule the extraction and the follow-on earthworks on consecutive days with the same machine on site.

“After the last tree came out, we had 50 voids to deal with and a site that still needed a cut. We staged the spoil from the trenching work and used it to backfill once the client was ready to move forward. One machine, one crew, the whole lot sorted without multiple mobilisations.”

Plant Hire Perth

• Each extraction leaves a void that needs backfilling or seeding depending on what comes next
• Trenching spoil can be stockpiled on site for reuse rather than carted away
• The PC55 that does the extraction can handle subsequent earthworks on the same job
• Combining grass tree extraction with follow-on site work reduces total mobilisation costs
• Call us to discuss sequencing both tasks in a single site visit