Australians love trees, but for those living in bushfire-prone areas, tree selection carries life-or-death significance. The wrong trees in the wrong places can turn a garden into a fire hazard, carrying flames to buildings and blocking escape routes. Conversely, thoughtful landscaping with appropriate species and strategic placement can actually protect properties while still providing shade, beauty, and wildlife habitat.
No tree is fireproof. All vegetation burns under extreme conditions. Fire-safe landscaping reduces risk but cannot guarantee protection. Always follow local fire authority guidelines and have an active bushfire survival plan.
Understanding Bushfire Behaviour
Effective fire-safe landscaping starts with understanding how bushfires threaten properties. Fires attack buildings through three main mechanisms:
Radiant Heat
Intense heat radiating from flames can ignite materials without direct contact. Radiant heat decreases rapidly with distance, making the gap between vegetation and buildings critical. This is why maintaining an Asset Protection Zone immediately around buildings is essential.
Direct Flame Contact
Flames reaching buildings directly through continuous fuel loads can ignite structures. Breaking fuel continuity with strategic gaps and low-flammability zones prevents fire from reaching buildings along the ground.
Ember Attack
Burning embers carried by wind can travel kilometres ahead of fire fronts, landing on and around buildings. Embers lodge in gutters, on decks, and against walls, starting new fires. Dense vegetation close to buildings provides fuel for ember-started fires to grow.
The Importance of Defendable Space
Creating defendable space involves managing vegetation in zones around your home. Most fire authorities recommend two zones:
Inner Zone (Asset Protection Zone)
Extending typically 10-20 metres from buildings, this zone should contain minimal fuel and no trees directly against structures. Any trees within this zone should be small, well-spaced, and kept pruned so no branches overhang roofs or touch walls. Understorey vegetation should be minimal, with non-flammable groundcovers like gravel or irrigated lawns.
Outer Zone (Fuel Reduced Zone)
Beyond the inner zone, this area should have reduced fuel loads with spaced trees, cleared understorey, and regular removal of fallen branches and debris. The outer zone slows fire approach and reduces radiant heat reaching buildings.
Specific requirements vary by location, fire danger rating, and local regulations. Contact your local council or fire authority for guidance applicable to your property. Some areas have mandatory setback and vegetation management requirements.
What Makes a Tree Less Flammable?
While no tree is fireproof, some species have characteristics that make them less likely to ignite and less likely to carry fire intensity:
High Moisture Content
Species that maintain high moisture levels in their leaves and bark resist ignition better than those with dry, papery foliage. Succulent leaves and thick bark indicate higher moisture retention.
Low Oil Content
Volatile oils in leaves and bark increase flammability. Many eucalypts are highly flammable precisely because of their oil-rich leaves. Species with low oil content are generally safer choices.
Minimal Bark Shedding
Stringy or peeling bark creates fire ladders, allowing flames to climb into canopies. Loose bark accumulates at tree bases, providing ground fuel. Smooth-barked trees are generally lower risk.
Open Canopy Structure
Dense, compact canopies trap heat and concentrate flammable gases. Open, airy canopy structures allow heat to dissipate and reduce fire intensity within the crown.
Avoid eucalypts and other high-oil species near buildings in bushfire zones. Despite being quintessentially Australian, their volatile oils make them among the most flammable trees on Earth.
Lower-Risk Tree Species
These species generally present lower fire risk, though placement and maintenance still matter:
Deciduous Trees
Leafless in summer when fire risk peaks, deciduous trees present reduced fuel loads during the danger season. Their lack of volatile oils also makes them slower to ignite. Suitable species include ornamental pears, maples, and deciduous magnolias.
Rainforest Species
Trees from rainforest environments typically have high moisture content and low oil levels. Lillypillies (Syzygium species), Tuckeroo (Cupaniopsis anacardioides), and Blueberry Ash (Elaeocarpus reticulatus) are examples suited to many garden situations.
Fruit Trees
Most fruit trees are lower risk, with high moisture content and minimal volatile oils. Citrus, stone fruits, and apples all present relatively lower fire risk while providing practical harvests.
Certain Natives
Not all natives are high-risk. Tuckeroo, Banksia integrifolia, and some Callistemons are considered lower risk than eucalypts. Check with local fire authorities for species recommendations specific to your area.
Tree Placement Principles
Where you plant matters as much as what you plant:
Setback from Buildings
Keep trees well clear of buildings. No branches should overhang roofs or be within 2 metres of external walls. Tree crowns should not touch each other, preventing fire running from tree to tree.
Clear Understorey
Maintain clear space beneath trees to at least twice the tree's mature height. This prevents ground fires climbing into canopies via understorey vegetation. Avoid continuous shrub plantings linking ground to canopy.
Break Canopy Continuity
Space trees so their canopies do not touch when mature. This prevents crown fire spreading from tree to tree. As a guide, space trees at least 2 metres apart at canopy level.
Consider Wind Direction
In most of Australia, dangerous fire weather comes from the north or northwest. Be particularly careful about fuel placement upwind of buildings. Locating low-flammability vegetation or non-combustible zones on the likely fire approach side provides greater protection.
Ongoing Maintenance
Fire-safe landscaping requires regular maintenance, not just one-time planting:
- Remove dead material: Clear fallen branches, dead leaves, and bark accumulations regularly, especially before summer.
- Prune lower branches: Maintain clearance between ground and lowest branches to prevent fire climbing into canopies.
- Keep grass short: Mow lawns regularly and maintain low fuel levels in the Asset Protection Zone.
- Clean gutters: Remove leaves and debris from gutters before fire season; these are prime ember traps.
- Water garden: Well-hydrated plants are more fire-resistant. Prioritise irrigation close to buildings during high-risk periods.
Living in bushfire country demands respect for fire risk, but it does not mean giving up on beautiful, functional gardens. Through careful species selection, thoughtful placement, and diligent maintenance, you can create landscapes that bring joy throughout the year while contributing to rather than compromising your property's protection.