Fire-Resistant Landscaping

By Cassy Aoyagi | Photography by Lesly Hall

Cassy Aoyagi is the president of FormLA® Landscaping, a Los Angeles-based, LEED-certified landscape design company that has added nearly 1.5 million square feet of native plant habitat to Los Angeles. She serves on the board of the U.S. Green Building Council’s thought-leading LA Chapter (USGBC-LA). Several of Aoyagi’s projects include firewise demonstration gardens. For Flora, she agreed to show us around her own garden in the Tujunga foothills, sharing the features that protect it from wildfire, as well as a few that could still use improvement.

Aoyagi at her Los Angeles home.

our home base is a little nook adjacent to chaparral, in the city limits of Los Angeles. My husband grew up wandering these mountains and probably knows every trail by heart. He made me love it, even more than the beach where I was raised.

Our garden is our solace, joy, and laboratory. Yet it terrifies those trained to see Los Angeles’ authentic foliage, like our oak trees and desert globemallow (Sphaeralcea ambigua), as dangerous. I don’t blame anyone for misconceptions. For decades, we’ve witnessed non-native hillside grasses like pampas and fountain grasses succumb to fire without understanding our role in placing them in danger’s way. We’ve been mandated to clear “brush” without understanding that the non-native grasses we buy at the nursery become this brush, increasing wildfire danger when they travel to wildspaces where they easily burn. We’ve heard that native plants “need fire” to propagate, as if this need inspires them to create fire. I do hope to dispel these myths.

Our hedgeline serves up an ever-evolving feast.”

To fearlessly love a garden like mine, it helps to understand a few things upfront. Wildfires are spread by embers that fly on the wind, looking for dry fuel. Palm trees and invasive grasses provide it, as do our homes, which are the most combustible and hottest-burning fuel on the landscape. Native foliage, on the other hand? When supported by smart irrigation, that’s hydrated, not the problem some may fear. As for needing fire…native plants do like it, infrequently and as long as things don’t get too hot.

Let’s wander. It’s easier to explain the features of the garden that keep us safe and where the true dangers lie one step at a time.

Every imaginable chaparral shrub wraps our property. We host no combustible, invasive foliage here! Our hedgeline serves up an ever-evolving visual feast of our favorite blooms, fragrances, tweets, and berries. Sunny yellow California flannelbush (Fremontodendron californicum)

kicks off the show in spring, followed by California lilac (Ceanothus ‘Frosty Blue’), Nevin’s barberry (Berberis nevinii), and Catalina cherry (Prunus ilicifolia ssp. lyonii). The show never stops.

Hydrated, low-growing foliage provides a defensive barrier from rolling embers.

When appropriately irrigated, this beauty can help intercept flying embers, the most likely source of home ignition. That’s actually a good thing, because hydrated materials don’t readily burn. The tall shrubs’ innate ability to hold hydration in dry summer heat protects us and them. Structurally pruned, biodiverse shrubbery like this also fights disease and infestation that might transform a single-species hedge into tinder.

An expansive native meadow sits inside the hedgeline. In spring, it fills with showy milkweed (Asclepias fascicularis) that fascinates our son, and California poppies (Eschscholzia californica) grown from seeds he scattered as a toddler. In one corner, the meadow slopes toward a deep swale that collects runoff from our slopes and a neighboring hardscape.

The swale and meadow play defense as we enjoy playtime, supporting the garden’s hydration, and offering firefighters safe, distanced space where they can defend our property. The dappled shade of a coast live oak (Quercus agrifolia) and western hackberry (Celtis sinensis) fills with birdsong and keeps the area cool.

Many people see danger in tree canopies. Palms and cypress might combust, however, fire scientists have trained us to value effective tree selection and placement as critical fire mitigation strategies. Thick trunks and branches won’t easily ignite. The oak’s dense canopy resists penetration by flying embers. Even the hackberry’s airy canopy can delay ember travels. Each year, we prune back branches that extend toward the structure of the home, in accordance with the defensible space principles that experts advise.

Any embers tempted to roll toward our home will encounter this defensive shift in elevation and a protective barrier of healthy, hydrated beauty.”

As we evolve our garden, we expand both the canopy and its distance from structures. A young ironwood (Lyonothamnus floribundus) now sits where an Italian stone pine succumbed to structural weakness near the ceanothus. We planted a California sycamore (Platanus racemosa) when we lost a towering eucalyptus. A baby valley oak (Quercus lobata) grows in the hackberry’s shade, ready to succeed it, while a rare Engelmann oak (Quercus engelmannii) sips from the swale.

Beneath the current canopy, we find more protection for our home and hearts. The menagerie of mid-sized, mostly medicinal foliage hides a retaining wall. Here, many species of native, sun-loving artemisia, buckwheat, sage, and mallow intersect with the alumroot, meadow rue, swordfern, and western columbine, which inhabit deep shade. Any embers tempted to roll toward our home will encounter this defensive shift in elevation and a protective barrier of healthy, hydrated beauty.

Nearer our home, low-growing foliage tickles our ankles. It also tickles us to know that the healthy, hydrated native plants will inhibit and even smother rolling embers. We hear the crunch of gravel beneath our feet. While expanses of gravel present too great an opportunity for embers to move freely, our small gravel patios form a useful defensible space for flammable furnishings and other creature comforts. Permeable concrete patios host lounge chairs and meet our sliding glass doors.

Should firefighters need to fight a home ignition point, they have this additional defensible space.

Behaviors are important too, and some of ours are respectable. We placed hydrated foliage between the neighbor’s wood fence and our home. We chose furnishings with no cushions, no umbrellas, often the most flammable items in a garden. We need no gas-powered equipment for maintenance, so we are free of related sparks and fuels. We consistently take protective actions like relocating or removing foliage that fails, structurally pruning shrubs, and raking debris from gravel.

Now that we’ve discussed our defenses, from the ember-intercepting tree canopy and hydrated hedges to our proactive choices that lead to smart behavior, let’s tour the greatest dangers on our property: our creature comforts, our behaviors, our beloved windows and wood.

Day-to-day, we behave imperfectly. Our son brings his toys in, but we leave a rope swing hanging from the oak. We keep tools with wooden handles lined up against the garage—negligent!

We hesitate most when it comes to addressing our greatest dangers. Our wood siding and window frames will easily burn if embers collect and build heat against them. Heat could melt the expanses of single pane windows, inviting embers inside. Replacing these features would require rebuilding entirely, leaving nothing of our historic structure. We did replace the roof with Class A materials—but only when it began to leak. As a society, better building materials and design practices must play an important role in “hardening” our properties to wildfire.

Now that you have the full picture— our garden, our home, our behavior—perhaps you see that the danger is me, is us. Human activities hold responsibility for 95 percent of wildfire ignitions. Our choices, from where and how to develop, build and plant to whether or not we put our toys away when we are done with them, determines the availability of combustible fuel. Authentic nature, effectively maintained and supported, mitigates the danger we create for ourselves. The sooner we realize that, the safer we’ll be.

The hedgeline in Aoyagi’s garden, featuring an assortment of well-hydrated native shrubs including California lilac (Ceanothus ‘Frosty Blue’).

 

9 Comments

  1. sensational! full of info and humility. just think of all the fires we could stop in their tracks if we followed these guidelines.

  2. Thank you so much for sharing this story and helpful information for native plant lovers that want to be thoughtful and defensive-minded when thinking about their fire risk.
    Cassy

  3. While this is an interesting and thought provoking article, this is the perfect opportunity to include a list of fire-resistant plants or books listing them. We are in the process of having our new house landscaped in a very fire prone area, Lake Tahoe, and this information would be very helpful at this time. I think this article missed an opportunity here

    1. Check out a classic, ‘Trees and Shrubs For A Dry California Landscape’ by Bob Perry. Updated 2nd edition. Principle of firescaping is covered.

      Also for descriptive lists of plants, California Native Plants for the Garden by Carol Bornstein, Dave Fross, and Bart O’Brien.

      CalFlora’s website is a listing of all Ca Native Plants, and their distrubutions, plus much more info.

      Larner Seeds of Bolinas has a selection of native seed, though how much for high altitudes, I don’t know. Village is a great natives nursery in Truckee. Some small natives growers sell in downtown Nevada City’s not-to-be-missed plant sale every Mother’s Day. They might have a list of nearby growers for the higher altitude regions they could get to you.

      Your local chapter of the California Native Plant Society will have a list of plant and seed suppliers, plus usually each chapter has spring and fall native plant sales open to the public. find a local chapter at #pfycalifornianativeplants

  4. Excellent essay Cassie
    I hope you are finding ways to educate County Fire.
    my warm regards
    Stephanie pincetl

  5. I think you have done an amazing job, and your property is very lush and attractive! My only concern is what happens when you can’t irrigate? Our State is in severe drought conditions. We are all being encouraged to conserve water. And at times water rationing has been implemented. You refer so often to a well hydrated garden. But what if we can’t hydrate? What happens then? Just wondering.

    1. Capturing and saving rainwater from every roof is a key element to any firescaping project. Guttering all roofs and flat surfaces (solar panels) and cache-ing water by using rain channels and storage structures can add to irrigation in dry seasons. There are great books and publications available from local Permaculture Groups (online and local chapters). Also, many Permie groups hold workshops and certification programs in building rain gardens–using every last drop of moisture. google “Permaculture groups” by county or zipcode.

  6. A very interesting and stimulating article. We are under water rationing now, on the coast of West Marin. Here in the Larner Seeds growing grounds and Demo Garden, we have 7500 gallons of water in catchment tanks. I’d appreciate guidance on how to figure out the best time to use this precious resource.

    Some of it went to support transplants of the rarer annual species we grow, like Clarkia concinna and Hosackia gracilis. Shrubs usually get no supplemental water here once established. Common wisdom was that shrubs like Ceanothus can be killed by an out of season combo of water and heat. Now it’s July, and who knows what lies ahead?

    So far, my employees are not crazy about the difficulties involved in getting the water out of the tanks and to the right spot. Hopefully this technology will improve.

    1. locate your closest Permaculture group by googling. They can show you how to correctly set up filters and distribution lines. Also, your local state/county Ag Advisor’s office may have some qualified Master Gardeners who are knowledgeable in this. SLO County’s does have a demo garden with such a setup. You’re close enough to Davis to visit the Native Plant demo garden there–contact the Hort Dept at UCD for info. (I would think winter to mid spring would be the ideal time to use the water to go deep, not summer; but depends on type of plant–woody vs herbacious?) kudos for capturing what would be runoff.

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