Scientists recommend succulents to protect buildings from bushfires
Gianna Sudholz says her house was saved when her water-rich succulent garden changed a bushfire's path. (ABC News: Tamara Clark)
In short:
Melbourne University is investigating what role water-rich plants can play in bushfire prevention.
A Natimuk home owner says her succulent garden stopped a bushfire destroying her home last month.
What's next?
Researchers say succulents are the "most extreme" example of a low-flammability plant.
Gianna Sudholz stood in the living room of her Natimuk farmhouse watching a fast-moving grassfire roar towards her on a catastrophic fire day.
The January 9 fire, which destroyed about 30 buildings in the western Victorian town, including some of her neighbours' houses, had already torn through kilometres of land as it headed directly for her home.
But as it grew near, something unexpected happened.
The Natimuk fire travelled rapidly on a narrow path. (ABC News: Jess Davis)
Ms Sudholz watched as the fire's behaviour changed when the flames hit her succulent garden.
It split into two paths, going left and right around her house, leaving it unscathed.
Gianna Sudholz's garden, with the succulent pigface, before the fire. (Supplied: Gianna Sudholz)
A strip of unburnt grass remained between the succulent garden bed and the house, while the paddocks and tree lines on either side were blackened.
"We have the road, then a 40-metre railway corridor, then low grass, and then we have a succulent garden. And that's where it split,"Ms Sudholz said.
Gianna Sudholz watched a fire approach from this room of her Natimuk home. (ABC News: Tamara Clark)
Ms Sudholz's husband, Natimuk fire brigade captain David Sudholz, said the moisture-rich plants ultimately stopped the house from burning.
"They knocked enough energy out of it to stop those last 20 metres," he said.
Ms Sudholz said she had formed an emotional attachment to the succulent garden, and she was eager to revamp it with new plants and edging.
David and Gianna Sudholz say their succulent garden helped save their home. (ABC News: Tamara Clark)
Firefighting succulents
Fire and plant scientist Jane Cawson agreed succulent gardens could take some of the power out of a bushfire.
Dr Cawson is a senior research fellow at the University of Melbourne who studies how different plants burn, and shape fire behaviour.
Jane Cawson is researching the relationship between plants and bushfires. (Supplied: Jane Cawson)
She said succulents were the "most extreme" example of a low-flammability plant.
Their thick, fleshy leaves store water and are hard to ignite compared with fine, dry summer grasses.
Dr Cawson said researchers were only at the beginning of testing whole plants and garden layouts in a way that gives clear, species-by-species answers.
"But there's already enough information to start making smarter choices about what you plant close to your house in a bushfire-prone area,"Dr Cawson said.
Dr Cawson has a succulent garden planted up against her bush-block home on Melbourne's north-eastern fringe.
She designed the garden, at Research, near Warrandyte, to have the best chance at protecting her home in the case of a fire.
Every element of Jane Cawson's garden was chosen for its fire-safe qualities. (ABC News: Supplied: Jane Cawson)
Plants that slow fire
Dr Cawson said house design, building materials, decks, fences, gutters and nearby trees all mattered too.
Many homes are lost to embers carried by the wind, rather than the initial fire itself.
She said plants with a high oil-load, such as stringybark eucalypts, posed particular ember risks.
She said bark and other organic mulches close to the house were extremely flammable too, and she recommended a mulch-free buffer of about 10 metres around buildings where possible.
"We do know that reducing fuel close to your house, adding breaks that fire struggles to cross, and choosing plants that are more likely to slow a fire than feed it are really important places to start,"she said.
Think in zones
Horticulturalist and Gardening Australia magazine editor AB Bishop said home gardeners could borrow a few key design tricks from fire ecologists and permaculturalists.
She said to think in zones around the property.
Firstly, she suggested having a very low-fuel inner zone where you might use succulents, low native ground covers and hard surfaces.
Then, she said to have a mid-zone with spaced-out shrubs and small trees.
Lastly, she suggested having a back zone for taller trees and wilder plants.
She said moisture-rich ground cover such as kidney weed and creeping boobialla could exist near the home without adding a lot of fuel, as long as they were kept low and tidy.
She also recommended swapping bark mulch for gravel or rocks within a few metres of the house, pruning low branches on trees to prevent a "ladder" for fire to reach canopies, and keeping lawns mown.
"None of us can control the weather or where a fire starts," she said.
"But we can absolutely control what we plant near our homes and how much fuel we let build up there.
"In a bad season, that might be enough to give your house and you a fighting chance."