Few things in nature are as frightening as wildfires. When we see aerial footage showing thousands of acres of forest glowing bright red, it makes us feel as if the whole world is ablaze.
Imagine what it’s like to be caught in the middle of such a maelstrom, like the 80,000 people who were evacuated from the path of the Blue Cut Fire this past August. For eight long days, it raged through the West Cajon Valley of Southern California, consuming 36,274 acres and destroying 105 homes.
Many of the folks who lived in those homes lost everything. Forced to sleep in tents on the blackened sites where their homes once stood, they had to wonder if it was worth it, building or buying a home surrounded so closely by wilderness.
Nearness to nature, the very thing that makes these home sites so appealing, is also what makes them so dangerous.
At least 99 million people, or about one-third of the U.S. population, live in the “wildland-urban interface” (WUI). The National Fire Protection Association (NFPA) of Quincy, Massachusetts, defines the WUI as “the line, area or zone where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuels.”
Wildfires aren’t something that only happens in the West. Some rural areas of Kansas greeted the spring with what local authorities called “the largest grass fire in Kansas history.”
In northern Oklahoma, the Anderson Creek fire that started on March 22 proceeded to burn more than 620 square miles (1,600 square kilometers) of prairie and cattle-grazing land, killing 600 cows. At least 16 homes and 25 structures were lost.
The National Interagency Fire Center predicted that, by October and November, the potential for significant wildfires is expected to be above normal in an arc spanning from Texas to New Jersey.
There are ways to make home sites nestled deep in Mother Nature’s bosom safer. While they can’t be made fireproof, they can be made fire-tolerant.
You’ve heard Smokey the Bear’s famous phrase, “Only you can prevent forest fires.” If we were to modify that slogan to fit our industry, it wouldn’t be nearly as catchy, but it might go something like this: “You, as a landscape contractor, can prevent your clients from losing their homes to wildfires.”
Creating defensible space
The NFPA uses the term ‘defensible space’ because it’s frequently used in the field. But it’s actually a misnomer, according to Michele Steinberg, NFPA’s division manager for wildland fire operations.
“We prefer instead to talk to a property owner about the ‘home ignition zone,’ modifying that to reduce the likelihood that his home will ignite and burn.”
The home ignition zone includes the home itself and everything around it, i.e., the grass, plants, shrubs and trees that are found within 100 feet of the structure. Within that space, the property owner has an opportunity—and a responsibility—to create less ignitable conditions.
“If a home doesn’t ignite, it won’t burn,” said Steinberg. “We’ve observed for more than 50 years that homes that are properly prepared can and do survive wildfires without intervention.”
It’s all about removing fuel loads.
When we look at someone’s property, we see turf, trees and shrubs. A firefighter sees fuel. Creating defensible space means learning to look at landscapes through his eyes.
Nevic Donnelly, a certified arborist and the owner of Austin-based They Might Be Monkeys Texas Tree and Land Company (the name came from his little girl, who saw him swinging from a tree and asked if he was a monkey), has learned how to do just that. He’s had advanced training from both the Texas Forest Service and the California Department of Forestry and Fire Protection in the management of wildfire risk.
As a member of the board of directors for the Texas chapter of the International Society of Arboriculture (ISA), he’s been helping to develop a wildfire mitigation qualification program for arborists.
Evaluating a property is the first order of the program. “You need to have somebody who understands fuel loads and the volatility of the surrounding vegetation to make that evaluation,” said Donnelly.
Fuel loads are the reason certain areas burn more than others. “The amount of fuel is the critical thing, and there’s a buildup of huge amounts of very flammable material in the chaparral areas of California, in particular,” said Dr. Michael Kuhns, extension forester and head of the Wildland Resources department at Utah State University in Logan.
This buildup, exacerbated by four years of drought, high temperatures and a drought-assisted bark beetle infestation that’s killed millions of forest trees, has fire experts worried. But as we stated earlier, this problem isn’t confined to the West. “If you live in the middle of New Jersey’s Pine Barrens, you could burn just as easily,” said Kuhns.
Picking the right kinds of plants
Creating a fire-tolerant landscape means putting the right kinds of plants in the right places. A lot of WUI properties have the wrong kinds of plants in the wrong places.
Cassy Aoyagi is president of FormLA Landscaping, Inc. in Santa Monica, California. Many of her upscale clients live in Los Angeles’ notoriously fire-prone hill areas. As a result, she’s had to learn about firewise practices, and about how to communicate the importance of them to her clients.
Fortunately for her, these practices dovetail nicely with her company’s eco-green, native-plant-focused approach. She tells her clients that native species that have evolved in areas that frequently burn have adapted to those conditions, and are thus more fire-resistant.
She’s discovered that the customer isn’t always right. “A client may say, ‘I want my yard to look just like my hillside,’ or vice versa,” said Aoyagi. “The professional who’s trying to please that client needs to explain that what he’s asking for will create a fire hazard, or exacerbate an already existing one.”
When she takes on a new property, she often finds exotic, invasive plants that are quite volatile, and can create fast-moving, intense fires. Ironically, many of these are recent additions, chosen for their drought-tolerance.
Two in particular, stipa tenuissima and Pampas grass, a.k.a. cortaderia selloana, are both highly invasive and highly flammable. “While they outperform natives during the good times, invasives tend to dry up when the going gets tough. The more invasives we have in our hills, the more we exacerbate the fire/flood/slide cycle.”
“I’m sure some well-intended people picked favorites that were climate and hillside friendly,” Aoyagi adds, “but they tend to displace some of the more native plants that take longer to burn. One of the most important things that I do as a landscape professional is to remove these plants.”
Instead of stipa, she’ll plant aristada purpurea, a native drought-tolerant grass that provides the same height and texture as stipa but presents no fire danger. For Pampas grass, she’ll substitute a fire-tolerant, non-invasive native wildflower species that also provides tall white plumes: hesperoyucca whipplei parishi, commonly named Our Lord’s Candle.
“In our area of central Texas, some of the big invasives are the Asian privets, Chinese tallow, Chinaberry and mandinas,” said Donnelly. “Their dense, woody underbrush creates heavy fuel loads in our natural areas, and should be kept out of landscapes.” As should Yaupon holly (ilex vomitoria), a highly volatile Texas native.
That’s right—a native. While natives are usually safer choices, the fact is, there’s no such thing as a ‘fireproof’ plant. All plants will burn; some just ignite more readily than others.
“In Utah, we have piñón juniper, a native conifer that’s quite flammable,” said Kuhns.
Conifers and palms catch fire quickly because they have lots of oils and resins in their leaves, needles and stems. If you’ve ever seen a dried-up Christmas tree go up like a torch during one of those demonstrations that fire departments conduct every December, you understand this.
How can you tell if a plant is volatile? Highly flammable trees and plants generally have fine, dry or dead leaves or needles within the plant’s habit. Some have loose or papery bark. The waxes and oils contained in their leaves, twigs and stems will give off strong odors when crushed. Their saps will be gummy and resinous and also have a noticeable smell.
By contrast, the saps of the safest species will be watery, without intense aromas. Their leaves will be green, moist and supple during the hottest, driest part of the year, and they’ll shed out once fall comes. Any deciduous species is naturally fire-tolerant, as are trees and shrubs with thicker barks.
Fire tolerance through maintenance
Mowing, irrigating and pruning are a big part of making landscapes fire-tolerant. Plants that are well-watered and well-maintained will create a living wall that’ll block intense heat.
“When it’s hot and dry, a juniper is basically a gasoline tree,” said Donnelly. “But a well-irrigated stand of juniper trees can actually stop a fire. Even an oak tree can explode in a fire if its moisture level is low enough.”
Unfortunately, in places where there’s been severe drought, many trees and shrubs have moisture levels that have dropped drastically. Watering restrictions make this situation even worse. Alternative water sources, such as rainwater recapture or graywater systems, may need to be employed to keep those trees alive and fire-tolerant.
Zoning a property
You can create a fire-tolerant landscape using a system that divides a property into zones. Zone 1 includes the home and attached structures, such as decks and fences, ending three to five feet out. Ideally, this should be a no-burn area consisting of pavers, concrete driveways or walkways and/or small, succulent plants.
Zone 2 is the area extending from Zone 1 to 100 feet from the home. It should be kept clean and green, with well-maintained and irrigated turf, ground covers, and other perennial plants separated by rock or other non-combustible surfaces or walls.
Trees in Zone 2 should be widely spaced, their crowns kept ten to 15 feet away from structures, chimneys, power lines and other tree crowns. All dead matter and debris should be removed.
No shrubs should be growing underneath trees that could provide ‘fire ladders’ up into the crowns. Lower branches should be pruned, with at least a six- to 15-foot clearance from the ground to the bottom of the canopy.
Zone 3 is the surrounding wildland area. If possible, its vegetation should be thinned.
It should be noted that the suggested distances pertain to level properties with moderate vegetation densities. They need to be increased up to 200 feet on steeper slopes with dense vegetation.
A yard full of mowed, green grass works like a fire-retardant carpet, as do manicured beds of herbaceous perennials. Yet another reason for preserving turf!
Many homes in the WUI burn when firebrands waft onto accumulated leaves and twigs piled under wooden decks. Keep those areas cleaned out.
Decks can also be made safer. “If you surround them with borders of two-inch river rocks, and put tight metal screens around them, it’ll prevent firebrands from landing and igniting,” says Donnelly. “Again, it comes down to fuel loads. A deck that’s open underneath will tend to collect organic matter. If a firebrand lands there, and lights the fuel, it will light up the bigger timbers.”
Your list of safe and unsafe grasses, plants and trees will vary, of course, depending on where you live. Firewise Communities, part of NFPA, has databases of fire-tolerant plantings for every state and region in the country, easily accessible online. Lists can also be obtained online from local university or county extension offices.
Mulches can burn, too
While you’re looking around a client’s property scanning for hazards, don’t forget about the mulch.
Some of them can slow a fire’s roll; others will accelerate it.
In 2008, an evaluation of the combustibility of various types of landscape mulches was conducted by the Carson City, Nevada Fire Department and some other entities. Eight different mulches were tested, including composted wood chips, shredded western red cedar, pine needles (also called pine straw); recycled rubber and wood chips treated with fire-retardant.
All of the mulches burned, but the one made from rubber tires came off the worst. (Not surprising—ever hear of tire fires that take days or weeks to put out?) It ignited easily and burned intensely for a prolonged period, reaching the hottest average maximum temperature of all the tested mulches, in excess of 630° F. It also produced the greatest flame heights, averaging over three feet.
Pine needles and shredded western red cedar were right behind rubber in flammability, while the composted wood chips were deemed the least hazardous.
Recycled rubber mulch could be in someone’s landscape without you or the homeowner even realizing it. It’s usually dyed to match redwood or other bark chips, allowing it to “hide in plain sight.”
If you have clients who live in the WUI, learn all you can about fire-tolerant landscape plants and practices. Wouldn’t it be a great feeling to know that work you did not only beautified, but actually saved someone’s home?