Planting your Garden for Bushfire Protection
Do you live in an area prone to bushfire? If you do, you need to know whether your garden is a bushfire hazard and if it is, how best to protect it. And more important, how to plant it to protect your family, your pets and livestock, and your home.
The first essential is to retain unimpeded access to the house and any other buildings on your land, and to identify combustible materials in the vicinity. Materials such as loose bark and leaf litter are highly flammable, particularly when they dry out during the bushfire season. They should be periodically removed from around the house, garden and roof gutters - and preferably composted. Long dry grass is also a fire hazard, so if you have a lawn, keep it mown, raked and watered.
The layout of your garden and the plants you grow there, play a vital role in protection. According to bushfire researchers, the main reason for the spread of fire is continuity of fuel. If your garden includes rows of trees and shrubs that touch each other - especially if they are highly flammable species - they should be thinned out or removed altogether.
The leaves of eucalypts release volatile oils that may or may not be hazardous, depending on the species and its placement. To avoid the risk of fire climbing the trunk and reaching the canopy, species with loose, fibrous bark that burns easily are best avoided or the bark scorched before the fire season arrives.
Conifers are even more hazardous because their fine leaves readily catch fire, and their resins then burst in flames. According to fire expert Dr Wendy Catchpole, pine trees in particular "have a high fuel load and they 'crown' (allow fire to move rapidly from treetop to treetop) so much more easily than eucalypts, which makes them more of a danger."
Fire retardant plants, strategically situated, should be the mainstay of your garden design.
As we all know, Australia is a fire-prone continent. Luckily, many of its 25,000 plant species have proven fire retardant properties. Those with the added benefits of self-regeneration and aesthetic value are of particular interest to the garden owner living with the threat of bushfire.
Be aware though, that no plant is completely fire-proof nor guaranteed to save your home, and that any plant exposed to prolonged intense fire will eventually burn.
Although numerous exotic species have fire retardant properties, most tend not to regenerate after fire, while those that do are often environmental weeds or have the potential to become so. A notable exception is Magnolia grandiflora Southern Magnolia, a fire retardant, non-invasive and usually well behaved tree from south-eastern USA. On account of its many desirable qualities, including its visual compatibility with much of Australia's native vegetation, I view this beautiful tree as an ‘honorary native'.
In planning and planting your garden for bushfire protection, keep your garden well watered. ‘Well watered' means different things to different plants. Certain plants, including many Australian species, are well adapted to drought. Several of these retain most of their sap and remain green while receiving little or no water for extended periods. Such plants are often fire retardant, and those of ornamental value have a special place in species shortlists for the fire retardant - and drought tolerant - garden.
For a start, choose fast growing plants with a high salt or water content. Acacia species are fast growing and several have foliage with a high water content. A good example is Acacia prominens Gosford Wattle, a highly ornamental tall shrub or small tree with blue-green foliage and showy lemon yellow flowers in Spring. Gosford Wattle is found in forest, from the New South Wales north coast down as far as the Hawkesbury River. Like many other plant species, it is generally best grown within or not far beyond its natural boundaries. This prevents it from becoming invasive, as in Victoria where it is sold by several nurseries and has become a significant environmental weed.
Angophora costata Sydney Red Gum and eucalypts with smooth bark may have a place in your garden, provided dead bark is removed when shed and leaf litter regularly raked. Sydney Red Gum is a medium to large tree of great character, with branches that develop a gnarled appearance, long drooping leaves and masses of white fllowers in spring. This tree is sometimes used as a spark shield on the fireward side of the house: Its canopy traps and extinguishes embers and sparks, thus preventing them from reaching the building. The natural distribution of Sydney Red Gum is from southern Queensland through coastal New South Wales and the lower Blue Mountains.
Although rainforest occupies only one percent of Australia, it contains around 40 percent of Australian plant species, among which are numerous fire retardant plants ideally suited to garden cultivation. These include Lilly Pillies such as Acmena smithii and Syzygium oleosum and their dwarf varieties that have become increasingly popular for small gardens.
Other fire retardant rainforest trees include Brachychiton acerifolius Flame Tree, a stately tree that drops its leaves before putting on a spectacular display of brilliant red flowers between October and December.
Cupaniopsis anacardioides Tuckeroo, is an excelllent shade tree with large, glossy green pinnate leaves and orange-yellow fruits.
Elaeocarpus reticulatus Blueberry Ash with pretty white or pink fringed flowers followed by bright blue berries; and Hymenosporum flavum Native Frangipini, a slender open tree that produces scented cream to yellow flowers, occupies little space and is well suited to even the smallest garden.
Melia azedarach var. australasica White Cedar, is a very attractive, fast-growing, rainforest tree with fern-like foliage and a general appearance resembling Jacaranda. During springtime it produces masses of mauve and white scented blossoms that remain on the tree for several months. These are followed by golden brown fleshy fruits, said to be toxic to humans although perennial favourites of feeding parrots and other birds.
White Cedar is one of the few deciduous Australian trees to drop its leaves during winter. It is often an excellent choice for a north or west facing aspect, filtering summer sun while admitting winter sun. Before leaf fall, processionary caterpillars sometimes defoliate the tree, although they cause no permanent damage. These little creatures are easily prevented from climbing the tree by winding double-sided sticky tape around the trunk during summer and/or by removing mulch from around the trunk base of mature trees.
Among scores of other fire retardant rainforest trees, Stenocarpus sinuatus Firewheel Tree deserves special mention. Although occurring naturally between north-east Queensland and north-east New South Wales, it is recommended for the Hunter and Sydney regions due to its breathtaking beauty and because it is non-invasive. Firewheel Tree is an upright tree that bears glowing orange-red wheel-shaped flowers in summer, their subtle beauty half-hidden among its shiny lobed leaves. I vividly remember watching a flock of parrots feeding on the seed pods an elbow length above my head while tiny honeyeaters fluttered around above them drinking nectar from the flowers.
Depending on your circumstances, some of the above species would be more appropriate than others. Ficus macrophylla Moreton Bay Fig, as an extreme example, is a large, wide spreading rainforest tree, suited only to the larger garden.
Shrubs with high salt content that are also of ornamental value include Atriplex and Rhagodia species Saltbush; and Carpobrotus glaucescens Pigface, a groundcover plant with fleshy, succulent leaves and bright magenta flowers. This and other groundcovers such as Dichondra repens Kidney Creeper, Kennedia prostrata Running Postman, Scaevola aemula Fairy Fan-flower and Viola hederacea Native Violet, overcome the need for flammable mulches such as pine bark and leaf litter. While these plants are developing, it is safer to use crushed brick or gravel mulches to protect surface roots and conserve soil moisture.
Wherever you live in Australia, there is sure to be an abundant choice of suitable species that occur naturally within your bioregion. For lists of species, contact your state's Australian Plants Society, conservation organisation, local council or native nursery.
The following fire retardant species, all of ornamental value and indigenous to the greater Sydney region (between Newcastle and Nowra, east of the Great Dividing Range), are not necessarily indigenous to other states of Australia nor even to your own locality.
Some fire experts dispute the fire retardant properties of Melaleuca nodosa, M. sieberi and M. styphelioides.
TREES |
|
| Botanical name | Common name |
| Acacia elata | Cedar Wattle |
| Acacia implexa | Hickory Wattle |
| Acacia melanoxylon | Blackwood |
| Acacia prominens | Gosford Wattle |
| Acmena smithii | Lilly Pilly |
| Alectryon subcinereus | |
| Allocasuarina torulosa | Forest Oak |
| Allocasuarina verticillata | Drooping She-oak |
| Angophora costata | Sydney Red Gum |
| Angophora hispida | Dwarf Apple |
| Banksia integrifolia | Coast Banksia |
| Brachychiton acerifolius | Illawarra Flame Tree |
| Brachychiton populneus | Kurrajong |
| Cassine australis | Red Olive Berry |
| Casuarina cunninghamiana | River Oak |
| Casuarina glauca | Swamp Oak |
| Croton verreauxii | Native Cascarilla |
| Cupaniopsia anacardioides | Tuckeroo |
| Diospyros australis | Black Plum |
| |
|
| Elaeocarpus obovatus | Hard Quandong |
| Elaeocarpus reticulatus | Blueberry Ash |
| Eucalyptus bauerana | Blue Box |
| Eucalyptus (Corymbia) gummifera | Red Bloodwood |
| Eucalyptus (Corymbia) maculata | Spotted Gum |
| Eucalyptus pauciflora | Snow Gum |
| Ficus coronata | Sandpaper Fig |
| Ficus macrophylla | Moreton Bay Fig |
| Ficus obliqua | Small-leaf Fig |
| Ficus rubiginosa | Port Jackson Fig |
| |
|
| Glochidion ferdinandi | Cheese Tree |
| Guioa semiglauca | |
| Hakea salicifolia | Willow-leaf Hakea |
| Hymenosporum flavum | Native Frangipani |
| Lophostemon confertus (Tristania conferta) |
Brush Box |
| Melia azedarach var. australasica | White Cedar |
| Pittosporum undulatum | Sweet Pittosporum |
| Rapanea howittiana | Brush Muttonwood |
| Rapanea variabilis | Muttonwood |
| Scolopia braunii (S. brownii) | Flintwood |
| Stenocarpus salignus | Scrub Beefwood |
| Streblus brunonianus | Whalebone Tree |
| Syzygium oleosum | Blue Lillypilly |
| Tristaniopsis laurina | Water Gum |
SHRUBS |
|
| Botanic name | Common name |
| Acacia sophorae | Coastal Wattle |
| Acacia terminalis | Sunshine Wattle |
| Atriplex cinerea | Grey Saltbush |
| Atriplex semibaccata | Berry Saltbush |
| Banksia aemula |
Wallum Banksia |
| Banksia marginata | Silver Banksia, Honeysuckle |
| Banksia robur | Swamp Banksia |
| Banksia spinulosa | Hairpin Banksia |
| Bursaria spinosa | Blackthorn |
| Callicoma serratifolia | Black Wattle |
| Correa alba | White Correa |
| Correa lawrenciana | Mountain Correa |
| Correa reflexa | Common Correa |
| Dodonaea megazyga | |
| Dodonaea triquetra | Common Hop-bush |
| Dodonaea viscosa ssp. angustifolia | Sticky Hop-bush |
| Dodonaea viscosa ssp. angustissima | Narrow-leaf Hop-bush |
| Dodonaea viscosa ssp. cuneata | Wedge-leaf Hop-bush |
| Eremophila debilis (Myoporum debile) | Winter Apple |
| Eupomatia laurina | Native Guava |
| Grevillea shiressii | Mullet Creek Grevillea |
| Hakea teretifolia | |
| Jacksonia scoparia | Dogwood |
| Lasiopetalum macrophyllum | Shrubby Rusty-petals |
| Melaleuca nodosa | Ball Honey-myrtle |
| Melaleuca sieberi | Sieber's Paperbark |
| Melaleuca styphelioides | Prickly Paperbark |
| Myoporum acuminatum | Mangrove Boobialla |
| Myoporum boninense (M. insulare) | Boobialla |
| Philotheca (Eriostemon) myoporoides | Native Daphne |
| Pittosporum revolutum | Yellow Pittosporum |
| Pomaderris aspera | Hazel Pomaderris |
| Pomaderris ligustrina | Privet Pomaderris |
| Rhagodia candolleana (R. baccata) | Coastal Saltbush |
| Senna (Cassia) artemisioides | Silver Cassia |
| Senna (Cassia) odorata | Southern Cassia |
| Solanum aviculare | Kangaroo Apple |
FERNS, ROCKERY, TUFTED PLANTS |
|
| Botanic name | Common name |
| Asplenium bulbiferum | Mother Spleenwort |
| Blechnum cartilagineum | Gristle Fern |
| Bulbine bulbosa | Golden Lily |
| Dianella caerulea | Blue Flax Lily |
| Dianella longifolia | Smooth Flax Lily |
| Dichopogon fimbriatus (Arthropodium fimbriatum) |
Nodding Chocolate Lily |
| Einadia (Rhagodia) hastata | Saloop |
| Enchylaena tomentosa | Ruby Saltbush |
| Lomandra longifolia | Spiny Mat-rush |
| Microlaena stipoides | Weeping Grass |
| Pelargonium australe | Austral Storksbill |
| Rhagodia candolleana (R. baccata) | Coastal Saltbush |
| Scaevola ramosissima | Purple Fan-flower |
| Stylidium graminifolium | Grass-leaf Trigger Plant |
| Thelionema caespitosum (Stypandra caespitosa) |
Tufted Blue Lily |
GROUNDCOVERS |
|
| Botanic name | Common name |
| Ajuga australis | Bugle |
| Carpobrotus glaucescens | Pig-face |
| Chrysocephalum (Helichrysum) apiculatum | Yellow Buttons |
| Dichondra repens | Kidney Creeper |
| Einadia (Rhagodia) nutans | |
| Isotoma fluviatalis | Swamp Isotome |
| Kennedia prostrata | Running Postman |
| Scaevola aemula | Fairy Fan-flower |
| Scaevola albida | Pale Fan-flower |
| Scaevola calendulacea | Dune Fan-flower |
| Scaevola hookeri | Creeping Fan-flower |
| Selliera radicans | |
| Themeda australis | Kangaroo Grass |
| Viola hederacea | Native Violet |
References
Australian Plant Study Group (1980)
Grow What Where Viking O'Neil, Ringwood, Victoria
NSW Rural Fire Service (1999)
Tree Selection for Fire-Prone Areas NSW Rural Fire Service/County Fire Authority of Victoria/Royal Botanic Gardens, Sydney
Webster, J. K. (2000)
The Complete Bushfire Safety Book Random House Australia, Milsons Point, NSW