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The science of low-flammability planting



Wildfires can be a major threat during hotter, drier months, but with smarter planting, you can help reduce the risk to your client’s property. This article from Fire & Emergency New Zealand explains how 


Property owners can do a number of things to help prevent wildfires. A key action is to create ‘defensible space’ – a carefully managed area around houses or structures, where flammable materials are removed or minimised.


An important component of defensible space is the planting of low-flammability species. Many decades of scientific testing have shown that while there is no such thing as a fire-proof plant, some species burn less well than others. 


Recently, there has been renewed research into plant flammability, including in New Zealand. A standard approach is to burn 70cm-long shoots on a device called a ‘plant BBQ’, which allows the testing of many species relatively quickly. This approach has been validated against other methods, such as the expert opinion of fire managers. 


How can I use low flammability plants to protect property?


It is best to use exclusively low-flammability planting in the priority safety zone of defensible space (0-10m) around your home and other structures. You should consider replacing any high-flammability plants or trees in Zone 2 (10-30m) around your home and structures with low-flammability plants.


At a larger scale, you could consider planting green firebreaks, strips of low-flammability vegetation established at strategic locations across the landscape to reduce fire spread. Green firebreaks have been widely used around the world and could be planted on the urban edge to help protect whole neighbourhoods. They have been deployed around New Zealand, for instance in Wellington and Porirua. 


Establishing low-flammability plantings


Establishment of low-flammability plantings should be planned months to a year in advance. First, identify which low-flammability species are suitable for your area. Key resources on this can be found atwww.checkitsalright.nz.  Low-flammability plants in New Zealand include native tree and shrub species, such as Griselinia littoralis (kapuka, broadleaf), Pseudopanax arboreus (five-finger), Coprosma robusta (karamu), and Aristotelia serrata (makomako, wineberry) – see table opposite for more examples.


For instance, planting a broadleaf hedge along a property could be a good way to help reduce fire spread. Next, source these plants from a local nursery, realising you may need to order stock a year in advance. Ideally, use plants grown from local seed stock, as these will be best suited to the local environment. Finally, plant them when soil moisture is at its highest, often May-August. 


Remember that it will be several years before certain plants are large enough to help protect your client’s home from fire. You should remind them of the importance of ongoing watering and maintenance, such as removal of any dead leaves and branches. Low-flammability plantings can help protect property from fire, but are best used as part of a wider range of fire prevention measures.  


Native plants with low flammability include: 


  • Plagianthus regius (ribbonwood, manatu, houi, manaui manatu, puruhi or whauwhi)

  • Fuchsia excorticata (tree fuchsia, New Zealand fuchsia or kōtukutuku)

  • Pseudopanax crassifolius (horoeka or lancewood)

  • Pseudopanax arboreus (five finger, puahou or whauwhaupaku

  • Coprosma robusta (karamu)

  • Coprosma autumnalis (kanono or raurēkau) 

  • Geniostoma ligustrifolium (hangehange or native privet)  

  • Coprosma australis (kanono or raurēkau)  

  • Coprosma propinqua (mingimingi) 

  • Coprosma repens (tree bedstraw, 

  • taupata, mirror bush, looking-glass bush, New Zealand laurel or shiny leaf)

  • Carpodetus serratus (putaputawētā, marbleleaf or bucket-of-water-tree)

  • Corynocarpus laevigatus (karaka or New Zealand laurel)

  • Griselinia littoralis (kapuka, New Zealand broadleaf or papauma)

  • Griselinia lucida (puka, akapuka or shining broadleaf)

  • Myrsine australis (mapou or red matipo)

  • Piper excelsum (pepper tree or kawakawa) Pennantia corymbosa (kaikomako, bellbird tree) 

  • Solanum aviculare (New Zealand nightshade or poroporo)

  • Sophora microphylla (kowhai) 

  • Coprosma crassifolia (mikimiki) 

  • Solanum laciniatum (poroporo, Tasmanian kangaroo apple) 

  • Aristotelia fruticosa (mountain, shrubby wineberry) 

  • Coprosma arborea (mamangi, tree coprosma) 

  • Dysoxylum spectabile (kohekohe, NZ mahogany) 

  • Pittosporum divaricatum  





Fire and Emergency New Zealand is New Zealand's unified urban and rural firefighting organisation.




For tips on fire safety, wildfire prevention and how to protect your property, visit checkitsalright.nz    

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