Tree Rootball Guying: Why It Matters and How to Choose the Right System
Once a new tree has been positioned in its tree pit, one of the immediate priorities is ensuring that it remains stable while its root system develops into the surrounding soil.
This is where tree rootball guying, or underground tree anchoring, plays an important role.
Rather than relying on visible stakes above ground, underground guying secures the rootball below the surface, helping to keep the tree upright and stable during the critical establishment period. It also creates a cleaner, stake-free finish in streets, public realm schemes and other urban landscapes. Concealed rootball anchoring is a key support option for newly planted trees while their roots establish.
When a root-balled tree is transplanted, its roots have not yet extended sufficiently into the surrounding soil to provide the same level of stability as an established tree.
Until that new root system develops, wind acting on the canopy can transfer movement through the stem and into the rootball.
Some natural movement of the tree is desirable, but excessive movement at the rootball can interfere with establishment. The purpose of an anchoring system is therefore to stabilise the rooting area while allowing the tree above ground to develop naturally.
Greenleaf Ireland’s ArborGuy Drive-In system, for example, is designed to secure the rootball below ground while still allowing natural trunk movement, which can support the formation of a strong trunk structure.
Traditional tree staking remains appropriate for some planting situations, but underground rootball guying can provide several advantages, particularly for larger root-balled trees and urban landscape projects.
Because the support system sits below the finished surface, there are no stakes and ties interrupting the appearance of the tree.
This can be particularly beneficial in streetscapes, commercial developments and high-quality public realm schemes where the visual finish is important. GreenBlue Urban specifically highlights underground guying as a way of achieving discreet, stake-free planting.
Rather than restraining the stem higher above ground, underground guying secures the rootball itself.
A typical system uses three anchoring points connected to wires or cables, with a wide webbing strap positioned over the rootball and tensioned using a ratchet.
This keeps the rootball in position while the surrounding root system develops.
Underground guying can also be considered alongside the rest of the tree-pit infrastructure.
These systems are commonly coordinated with structural tree pits, irrigation and aeration systems, specialist soils, tree grilles and other planting components.
That is important because anchoring should ideally be considered during the design and construction of the tree pit — not when the tree is already arriving on site.
A further advantage of underground rootball guying is that it secures the rootball without rigidly restraining the trunk or crown. This allows the above-ground structure of the tree to move naturally in response to wind loading.
This movement is an important part of tree establishment. As a young tree responds to wind forces, it develops greater trunk taper and a stronger anchoring root system, helping it become increasingly self-supporting as it establishes.
By contrast, overly rigid above-ground staking can restrict this natural movement. Prolonged or excessively tight staking may reduce root development and trunk thickening, potentially leaving the tree more dependent on artificial support when the staking is eventually removed.
Underground anchoring therefore provides the necessary stability at the rootball while allowing the tree above ground to respond naturally to its environment and develop the structural strength required for long-term stability.
On many urban tree-pit projects, the anchoring system can be installed as part of the tree-pit build-up itself.
Where a pavement support lattice or structural soil-cell system is being constructed around the rooting area, the anchoring points can be positioned at the base of the tree pit during the early stages of installation.
The pavement support structure is then progressively assembled and the specified rooting soil introduced into the tree pit.
As the soil volume is built up around the structure, the anchoring points become firmly integrated within the completed tree-pit construction.
By the time the tree arrives, the underground infrastructure is already in place.
The rooting volume has been established, the pavement support system has been built, and the anchoring points are ready to receive the rootball.
Once the tree is lowered into position, the pre-installed anchor wires or cables can be brought up around the rootball, the webbing strap positioned, and the system tensioned.
This sequencing has several practical advantages.
It enables the contractor to coordinate the anchoring system with:
It can also avoid the need to disturb the completed rooting environment later.
For designers, it reinforces an important principle: tree anchoring should form part of the overall tree-pit design rather than being treated as an accessory added at the end of the installation.
There is no single underground anchoring method that is suitable for every tree pit.
The appropriate approach depends on factors including:
Within the Greenleaf Ireland ArborGuy range, there are three principal approaches to rootball anchoring:
AnchorPlate, Deadman and Drive-In.
Each is designed to achieve the same basic goal — securing the rootball during establishment — but the anchoring method differs according to site conditions.
The ArborGuy AnchorPlate is a particularly low-profile underground anchoring system.
It is designed for situations where excavation depth may be restricted, or where driving an anchor further into the ground is undesirable because of underground services or structures.
The system uses three high-strength steel anchor wires together with a single-piece wide webbing strap and integral ratchet tensioner.
One of the key advantages is that the AnchorPlate does not require a drive-in anchor.
This makes it particularly suitable where a traditional driven system could interfere with services or other below-ground infrastructure. Greenleaf Ireland also notes that its low profile eliminates the need for further excavation beneath the anchor.
Where might AnchorPlate be used?
Potential applications include:
Greenleaf Ireland lists AnchorPlate options corresponding with RootSpace depths from 400mm to 1200mm, with standard systems suitable for trees below 45cm girth. For trees above 40cm girth, two kits are specified, subject to consideration of crown size, density, exposure and prevailing wind conditions.
This makes AnchorPlate particularly useful where the support system needs to remain within the designed depth of the tree-pit construction.
The ArborGuy Deadman Anchor offers a non-driven alternative.
Rather than installing an anchor vertically into the subsoil beneath the tree pit, deadman anchoring points are positioned at the base of the excavation.
Greenleaf Ireland describes these as heavy timber or metal base anchors arranged in a triangular configuration. Cables are secured around the three anchor points before the webbing strap is passed through the cable ends and tensioned over the rootball.
Where might a Deadman system be used?
The Deadman approach is particularly useful where there is concern about utilities in the immediate vicinity of the tree pit.
Because the anchoring points are positioned within the excavation rather than driven deeper into unknown ground, the system can provide a practical solution in utility-sensitive urban locations. GreenBlue Urban specifically describes the ArborGuy Deadman Anchor as a non-driven solution suited to utility-sensitive sites.
Potential applications include:
Greenleaf Ireland lists the Deadman system for trees up to approximately 40cm girth.
The Deadman arrangement also lends itself particularly well to being incorporated during the initial tree-pit build-up, with the anchor points placed at the base before the remainder of the tree-pit structure and rooting medium are installed.
Where site conditions permit anchors to be installed into the ground beneath the tree pit, the ArborGuy Drive-In Anchor provides a concealed underground anchoring solution.
Three anchors are driven into the base of the tree pit and connected by high-strength wires to a wide webbing strap positioned over the rootball.
An integral ratchet then tensions the system.
Once the installation is complete, the whole assembly remains below the finished landscape surface.
Where might a Drive-In system be used?
The Drive-In system is suitable for both urban hardscape and parkland softscape environments where the underlying ground conditions allow anchors to be driven safely.
Greenleaf Ireland lists two principal sizes:
Composite and aluminium anchor options are available.
The ArborGuy anchor itself has been designed to penetrate compacted subsoil and develop a secure groundlock. Greenleaf Ireland states that testing has shown a single anchor driven into subsoil can withstand forces in excess of 3,000lb.
As with any driven anchoring system, the location of underground utilities and the suitability of the ground beneath the excavation need to be understood before installation.
The difference between the three systems largely comes down to what lies beneath the tree.
Drive-In is typically suitable where there is adequate subsoil beneath the tree pit and anchors can safely be driven into it.
Deadman provides a non-driven solution where underground utilities or other constraints make deeper anchoring unsuitable.
AnchorPlate provides a particularly low-profile option for shallow tree pits, podium construction or areas where nearby structures or services limit excavation depth.
Selection should therefore take place alongside the design of the overall tree pit.
Before choosing an anchoring system, consider:
These factors can determine not only which system is appropriate, but also when and how it should be incorporated into construction.
Selecting the right system is only part of the process.
Correct positioning and tensioning are essential if the rootball is to be restrained effectively.
The ArborGuy systems use wide webbing to distribute the restraint across the rootball rather than applying a narrow point load. Greenleaf Ireland states that the wide webbing is designed not to cut into the rootball, removing the need for a separate protection mat on its AnchorPlate and Drive-In systems.
Maintenance requirements should also be considered.
For the ArborGuy AnchorPlate, Greenleaf Ireland specifies that the strap should be re-tensioned approximately three weeks after installation and again after three months.
Installers should always follow the relevant product datasheet, installation guidance and project-specific tree-pit detail.
Underground guying is a relatively small component within a complete urban tree-pit system, but it performs an important role during one of the most vulnerable stages of a tree’s life.
Good tree planting is rarely about one individual product.
Soil volume, root management, irrigation, aeration, drainage, pavement support and anchoring all need to work together if a tree is to establish successfully within a constrained urban environment.
Planning the anchoring system early also makes life easier on site.
When the anchor positions are coordinated with the tree-pit structure from the beginning, the pavement support system and rooting soil can be installed around them. By the time planting takes place, the tree pit is prepared and the anchoring components are ready to secure the incoming rootball.
The objective is simple: keep the rootball stable while giving the tree the environment it needs to establish naturally.
And, like most aspects of successful urban tree planting, achieving that objective starts with designing what happens below ground long before the tree arrives on site.
Greenleaf Ireland offers ArborGuy AnchorPlate, Deadman and Drive-In underground guying systems for different tree sizes and site conditions.
For project-specific guidance, the Greenleaf Ireland team can help identify an appropriate anchoring solution based on tree size, rootball dimensions, tree-pit construction, excavation depth and below-ground constraints.
Start typing to search...