Sept. 24 2021 06:00 PM

Learn how to plan for fire-resistant landscape and irrigation design.

As the summer comes to a close, the wild weather season has featured hurricanes, monsoons, floods, tornados and wildfires across the U.S.

While the landscaping and irrigation industry cannot prevent wildfires, the importance of building and maintaining fire-resistant landscapes continues to gain relevance to minimize the impact of a growing wildfire season across the western half of the U.S.

“Landscape maintenance is critical to fire defense,” says Los Angeles-based Cassy Aoyagi, president of FormLA Landscaping. “In much of the West it needs to occur year-round, not only during our traditional fire season.”

Aoyagi recommends landscapers keep strict adherence to keeping the 5 to 10 feet closest to the building or home free of anything that could ignite or help collect embers that could spark a fire in the yard, home or building.

“Throughout the garden and yard, foliage should be structurally ‘limbed up’ and well-hydrated,” says Aoyagi. “Dead material should be removed immediately. Walks and foundations should be swept of leaves and needles, and gutters should also be kept free of them.”

Irrigation intelligence

The simple act of utilizing an irrigation system helps manage a landscape in its defense versus fire, as well-hydrated materials do not burn.

“An approaching fire will have to dry out well-irrigated plants before it can ignite it,” says Aoyagi. “For this same reason, irrigation that ‘hydrates’ a home, a roof or fencing is also fire-defensive.”

For garden use, Aoyagi recommends installing subsurface, low-flow drip irrigation on weather-based controllers. The value of subsurface systems in creating a fire-resistant landscape is that it hydrates the soil and keeps it cool at the same time. Applying a deep organic mulch also helps in keeping soil temperatures cool.

Their underground location helps defend them from fire, and although weather-based controllers probably will not respond to fire like it is a weather event, they still can adapt to weather faster than manual operation, maintaining a healthy landscape that is more resistant to fires.

“Overhead spray systems also have advantages,” says Aoyagi. “They can wet and cool foliage and mulch in the event that a property is threatened by fire, and they can also directly douse embers, which has several advantages in fire defense.”

A matter of materials

When it comes to building a fire-resistant landscape, the selection of landscaping and irrigation materials often gets overlooked in favor of budget, personnel and project timeline issues. This can create large hazards and unknowingly create a dangerous environment.

“When it comes to sprinklers and irrigation, if metal and copper pipes and heads are an option, it is always an advantage in fire resistance over plastic,” says Aoyagi. When designing, “think about a design that is least vulnerable to both flames and embers.”

While landscapers can look at what they are planting and maintaining as a risk to fire, Aoyagi says wind-driven embers are the most common source of starting fires, not landscape foliage, so landscapers must take a comprehensive view of not only what is planted, but where it is planted.

“Landscapes can be strategically designed, built and maintained to defend homes,” says Aoyagi, whose company hosts fire-defensive garden tours. “You have to reorient people’s understanding of fire-defensive strategies by always speaking to the vulnerabilities of the home and the topography first.”

Client communication is key in creating or modifying a landscape to become fire-resistant. According to Aoyagi, the first step is always looking at the current landscape to identify immediate threats.

“We can increase resistance when we add fine-wire mesh to block access where embers might collect or access the interior of a home like our vents and gutters,” says Aoyagi. “You want your clients to feel empowered, not fearful, and generally you have to update their understanding of what a fire-defensive landscape looks like and where the true dangers lie. When we design fire-defensive gardens, we focus on speaking to the beauty and livability, then highlight how specific features also help defend their homes.”