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Fight Fire with Landscaping
1 Jul, 2008 By: Janet Aird LivescapesHow to help protect your clients' properties from wildfires.
Landscapers can play a vital role in protecting their clients' homes from wildfires. When you design and maintain a fire-safe landscape — or firescape — you interrupt the paths that wildfires would take and limit the amount of fuel available to them. You also give firefighters space to fight the fires.
 This diagram shows thinned trees in the four firescaping zones. |
Most homeowners don't want a completely fireproof landscape, though, says Owen Dell, a Santa Barbara, CA-based landscape architect who has been firescaping for 20 years.
"The ideal fire-safe landscape is concrete," Dell says. "Once you leave that ideal, you start adding fuel." The key to a beautiful and fire-resistant landscape is balance, he says. "Put in plants that are as reluctant to burn as possible and keep the property clean."
 This is an example of Zone One firescaping in Arizona. |
Kinds of Fire
Wildfires spread in predictable ways. Crown fires leap from treetop to treetop and can move through an area in about 30 seconds, says Michele Steinberg, Firewise Communities support manager for the National Fire Protection Association. Their flames can ignite any flammable material in their path — including homes. If the flames are close enough, structures can ignite from the heat alone.
 Firescaping design features include low-growing, well irrigated plants, a wide path and a low wall to reduce slope near the house. |
Burning embers called firebrands break away from crown fires and are also very dangerous, says Douglas Kent, a landscape architect who has been firescaping since 1995.
"Firebrands are the things to defend against," Kent says. "They can blow a mile ahead of the fire." When they land on a flammable roof, they can grow until they erupt into flames.
Ground fires burn through grasses and groundcovers. Although they travel more slowly than crown fires and firebrands, they spread easily and can climb up trees.
Design
Firescaping consists of up to four zones of defensible space around a home. They're progressively less fire-resistant as they radiate out.
 A typical Zone One firescape consists of mostly low-growing shrubs and wide paths. |
Placing the right plants in the right places is critical to firescape design. If they aren't in the right place, they won't do well and you'll end up with dead, flammable material, Dell says. Choose plants that suit your climate and the location in which you plant them. Put them in groups with the same requirements for light, soil type and water.
Although the plantings in each zone are different, the principles are the same. To stop ground fires from spreading, group plants in small beds or "islands." Separate them with wide paths of noncombustible materials such as stepping stones, compacted soil, gravel or decomposed granite.
Group plants of similar heights together to avoid "laddering," which allows fires to leap from groundcovers to shrubs up to the crowns of trees. Because larger vegetation produces larger flames, space taller plants farther apart than shorter ones.
Plant trees so their canopies will be 10 ft. apart at maturity, and away from power lines. Some experts recommend pruning trees to 10 to 20 ft. above the ground to avoid laddering, but this harms the trees, Kent says: "The lower branches cause the trunk to gain in girth. When you 'limb up,' all the plant's energy goes up, and it's easy for the tree to topple in the wind." Instead, keep all flammable material, including vegetation, away from the tree.
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