In recent years, severe fires have moved beyond the rural fringe and into metropolitan suburbs of Canberra and Melbourne.
Planning a garden using the principles in Section 4 can help reduce the bushfire risk in suburban areas. However, a garden only forms one component of preparing for bushfire. There are many other things to consider (see Section 1).
The hard landscaping in a garden involves making changes to material selection. Use brick, stone, steel or concrete materials for retaining walls and garden edging. Gravel products are suitable for pathways and mulches. These design selections can reduce fire risk from within the garden.
In most areas timber should be avoided as this can provide a way of directly moving a fire further into the property. In a garden in a high bushfire risk area, timber fences should be replaced with non-combustible options.
Swimming pools or ponds can help when creating a defendable space if placed between the most likely direction of a fire and the house.
Removing other potential fuel sources from directly around the house is important. This includes sheds, garden tools and machinery areas, woodpiles, outdoor furniture, clothes lines and shade screens. These should all be positioned at least 10 metres away from the house.
Planting design should focus on plants that have low flammable characteristics that are placed away from the house. Plants in containers can be an effective way to create seasonal interest and bring productivity into the suburban garden. They can also be readily moved away from the house.
EXAMPLE: SUBURBAN MODEL GARDEN
Existing indigenous trees of Eucalyptus polyanthemos (Red Box) have been retained in the suburban garden but those within 10 metres of the house have been removed. Vegetation beneath the trees is confined to shortly-mown lawn, very low shrub and fleshy ground cover plantings. These plantings avoid ladder fuels that can carry fire into the canopy. Any low hanging branches have also been removed up to 2 metres as part of the regular garden maintenance.
A dual access driveway at the front of the property has been provided. The pool has been placed between the house and a possible fire front. It includes a small area of adjoining timber decking that is well separated from house. Stone paving and gravel pathways are used in the area directly surrounding the house. The pathways have been designed to provide separation between garden beds and areas of low fuel around the house.
The slope of the site has been partially terraced using large rocks. Both the rear portion of the garden and the lawn area to the east of the house are maintained as open lawns. This design element reduces fuel loads within the defendable space.
Garden beds are separated by areas of maintained lawn that break up fuel continuity. The lawn also allows easy access for maintenance throughout the garden.
The clothes line and shed, which includes swimming pool chemicals and fire wood, are located in this area well away from the house. The eastern boundary of the garden has three large non-combustible water tanks adjoining the fence. These help shelter the house from radiant heat and provide water for the adjacent vegetable garden. The vegetation is low around the tanks so that they can be accessed if there is a fire.
Plants chosen for the model garden have been selected for their firewise properties.
At the back of the pool area is a mixed display planting of short grasses and ornamental shrubs. These include Festuca glauca (Blue Fescue), Cotinus ‘Grace’ (Smoke bush); Echium candicans (Pride of Madeira), Euphorbia characias subsp. wulfenii (Wulfen Spurge) and Senecio vira-vira.
Adjoining the paving area (between the house and the pool) are low-growing (to 30 centimetres in height), drought-tolerant herbaceous plants. These include Aloe x spinossimum (Spider aloe), Chrysocephalum apiculatum (Common Everlasting), Coreposis ‘Moonbeam’, Dianthus caryophyllus (Pinks) and Nepeta fassenii (Catmint).
A mix of grouped shrub plantings (0.5-2 metres in height) is located away from the house. These shrubs are pruned after flowering to maintain an open form, reduce plant litter and encourage repeat flowering.
These Australian native plants include Alyogyne hueglii (Native Hibiscus), Banksia blechnifolia (Creeping Banksia), Correa pulchella (Salmon Correa), Crowea exalata, Eremophila maculata (Emu Bush) and Philotheca (Bounda Beauty).
PLANTINGS UNDER THE LARGE EUCALYPTUS
To the front of the property and under the medium-sized Eucalyptus polyanthemos (Red Box) are small clipped hedges. These are maintained to a maximum height of 1 metre. They include Acacia acinaea (Goldust Wattle), Syzygium fancissii ‘Little Gem’ (Dwarf Lily Pilly) and Westeringia fruticosa (Native Rosemary).
Adequate separation between these low shrubs and the mature trees is ensured by under-pruning any low branches and regular maintenance of the hedges.
Low-growing, drought-tolerant Australian herbaceous perennials (to 30 centimetres in height) are planted to the front of the hedges. They include Brachyscome mulifida (Cut-leaf Daisy), Chrysocephalum apiculatum (Common Everalsting), Dampiera linearis (Common Dampiera) and Scaevola albida ‘Mauve Clusters’ (Fan Flower).
Close to the house are raised, steel-edged vegetable gardens. These contain a mix of annual vegetables.
Pennisetum clandestinum (Kikuyu Grass) – a tough, hard-wearing turf grass – is planted in the lawn areas. It is managed at a low height and is irrigated over summer. This helps to maintain a defendable space.
SECTION 5: CHOOSING SUITABLE PLANTS
After planning and designing, the next task is to choose suitable plants for the garden. Some plants have intrinsic characteristics that reduce the likelihood of ignition. Choosing these plants and locating them correctly will help reduce bushfire risk within a garden.
There are a number of characteristics that influence how flammable a plant is. It is important to know which factors contribute to plant flammability. This will assist in making informed decisions when selecting plants for a garden.
A consistent approach for determining the flammability rating of a plant is provided by the Plant Selection Key (see Section 7).
The key takes the user through a series of questions about the characteristics of the plant and provides:
an overall flammability rating
advice on where to locate that plant within a garden.
Before working through the key, there are elements of plant flammability that should be further explained.