Landscaping for bushfire garden design and plant selection



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TYPES OF GARDENS


The following four gardens provide practical examples of landscaping for bushfire, using the design principles outlined earlier in this section.

Plants have been selected for each location for their characteristics of low flammability (see the Plant Selection Key in Section 7).

The example gardens also highlight the importance of proper maintenance.

Please note the sections below contain plant names in Latin.


LEAVING EARLY


In high-risk areas, bushfire behaviour will be driven by the heavily vegetated landscape. While garden design and maintenance can improve the chances of a house surviving a bushfire, do not rely on these in isolation. A garden will not provide protection in a bushfire.

A holistic approach to bushfire preparation is critical. Appropriate water supply, access, house construction and general property maintenance are all important.

On Severe, Extreme and Code Red days leaving early will always be the safest option.

MODEL 1: COASTAL GARDEN


Establishing and maintaining a garden in a coastal location can be particularly challenging. Strong, seasonal winds, sometimes coupled with high levels of air-borne salt, provide difficult growing conditions. These can reduce the height and modify the shape of many garden plants and limit overall growth potential.

Coastal landscapes are also typically exposed to high light conditions and elevated temperatures. These factors, coupled with often sandy, shallow soils with poor water retention, mean that horticultural practices to retain soil moisture, such as addition of organic matter and mulches, become critical for garden success.

Creating microclimates through shelter and screening can minimise these problems and enable a larger range of plants to be grown successfully.

When planning a coastal garden, consider the local site’s topography, aspect and neighbouring vegetation.

Gardens located on slopes are more likely to experience the effects of strong winds than those in protected locations.

North-facing gardens are more likely to rapidly dry out during hot summer days. Those in a southerly aspect are more protected.

Natural vegetation growing near the coast is often highly flammable and in some places will be in close proximity to a home garden.

In any of these situations the application of the design principles, such as incorporation of a defendable space and location and arrangement of plants, is particularly important.


EXAMPLE: COASTAL MODEL GARDEN


The paved sitting area, lawn and low-sitting wall provide separation between the house and the direction of the most likely fire hazard.

A small tree is located well away from the house. It provides shade and may also catch embers during a fire. Planting beneath the tree has been kept very low and short. The lower branches of the tree are pruned up to 2 metres from ground level to prevent a fire from moving into the canopy. Behind the tree, a fleshy-leaved hedge 5 is managed as a long, barrier planting. This will also help catch embers.

The area within the property that is most likely to be impacted first by fire has been planted out as a vegetable garden and orchard. Good separation is provided between all trees and garden beds to help slow fire spread. The entire area is irrigated to keep plants lush over hot summer days. The service area, with a shed and washing line, is kept well away from the house in the garden’s south-west corner.

Large steel pots with upright succulent plants soften the paved area and can be moved away from the house during summer. The low stone wall acts as a radiant heat barrier and forms an attractive garden feature.

The area north of the house includes smaller growing succulents that minimise the amount of flammable material near the carport. Both the carport and the pergola against the house are constructed of steel. Using this material avoids adding fuel close to the house. The driveway and carport have 4 metres vertical and horizontal clearance for vehicle access.

Small deciduous trees have been planted well away from the house and carport. This ensures there are no overhanging branches and they do not obstruct the driveway. Good separation between the canopies has been provided. Other characteristics such as smooth bark and an open habit contribute to the low flammability rating of these trees.

The gravel driveway and portions of the front garden include bands of decorative stone as a design feature. The front garden also includes strips of lawn between the beds of low shrubs and groundcovers. This provides good separation between plantings and reduces potential fire movement across the garden.

Plants chosen for the model garden have been selected for their firewise properties.


SMALL ORCHARD AND VEGETABLE GARDEN


Located on the coastal side of the property, this area adjoins the remnant indigenous vegetation. The orchard includes widely spaced Citrus trees (Lemon, Orange) and a lawn of Stenotaphrum secundatum ‘Sir Walter’ (Sir Walter Buffalo Grass). The vegetable garden includes small soil-raised beds edged by rock and is drip irrigated from tank water on site.

HEDGE


The plant used for the medium-sized hedge (2m x 1m) is Corynocarpus laevigatus (Karaka). It is a fleshy, evergreen shrub from New Zealand. While maintenance of the hedge is important to reduce plant litter build-up, it is a good example of a firewise plant. This species retains very little dead foliage and has low levels of oils, waxes and resins in the plant tissues.

PERENNIALS


A decorative mix of evergreen and herbaceous perennials and short grasses are planned for this part of the garden to provide colour and textural qualities for most of the year. Where located near the tree, they will be maintained to a low height to ensure good separation.

Plants selected include Festuca glauca (Blue Fescue), Euphorbia (Compton Ash), Kniphofia cv. (Red Hot Pokers), Perovskia atriplicifolia (Russian Sage), Phormium cv. (New Zealand Flax), Salvia nemorosa (Woodland Sage), Salvia microphylla (Baby Sage) and Sedum (Matrona).


SMALL TREES


The trees are planted across the garden with low, herbaceous vegetation planted beneath them. This planting arrangement will maximise separation between the vegetation and their canopies. The canopies will also be maintained 2 metres apart to reduce fire spread.

Brachychiton x rosea (Hybrid Flame Tree) has been placed more than 10 metres from the house. It has an open, branching habit, fleshy stems and plays a role in ember catching.

Ficus carica (Common Fig) is a small, deciduous, productive tree with an open habit, smooth bark, large leaves stems and plays a role in ember catching.

Lagerstroemia indica (Crepe Myrtle) is also a deciduous tree with smooth bark and open habit. In this garden it will be managed as a pollarded tree (a tree whose top branches have been cut back to the trunk so that it produces a dense growth of new shoots). This treatment reduces its overall height, as well as keeping lower branches and canopy clear from the ground.

LOW SUCCULENT PLANTINGS


A small linear bed planting of succulents is planted near the house and carport. In the example above, the succulent plants are low in height, have very low flammability and are set well below the house windows. This provides good separation between succulent plantings and vulnerable areas of the house.

Species used here include: Agave attenuate (Swans Neck Agave), Agave parriyi, Aeonium arboreum (Tree Aeonium), Cotyledon macranthra (Flap Jacks), Klenia madraliscae (Blue Chalk Sticks), Aeonium ‘Velour’ and Sedum x rubrotinctum (Jelly Beans).


GROUND COVER INDIGENOUS PLANTS


These consist of low-growing, indigenous ground cover plants. They have low flammability features, such as leaf and stem succulence and low litter carrying.

They include Carpobrotus rossi (Karkalla), Rhagodia candolleana (Coastal Salt Bush), Atriplex cinerea (Grey Saltbush), Zygophyllum billardierii (Coast Twin-leaf) and Correa alba Prostrate Form (Dwarf White Correa).


TURF AREAS


The turf species used here is Stenotaphrum secundatum ‘Sir Walter’ (Sir Walter Buffalo Grass), a soft, low-growing and drought-tolerant grass.
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