Intercept Fire with Trees

Harness Trees to “Catch” Embers Before They Reach Your Home

May 12, 2020. By Cassy Aoyagi: Landscapes can speed or slow fire’s travel to our homes. The creation of treeful spaces is among the 10 firewise actions we can take in our gardens to protect our homes.

January 2025 Notice: This article is designed to provide long-term guidance.
If you have been asked to evacuate, Get Set and Go!

On sunny days, the nearly 40-year old oak trees at the left shade The Forbes Mountain Retreat

Is your head spinning? It happens! We are accustomed to thinking of trees as sources of fire danger. In some cases, it’s true. Palms form fire-bombs. Cypress and Eucalyptus trees also pose dangers, as will any tree that connects to your roof or eves. Yet, the right trees, smartly planted in the right place can help defend homes.

Before we get to what trees to plant where, let’s take a quick look at their defensive qualities. Most homes ignite from flying embers collecting next to a home where they engage kindling and build enough heat to ignite a home. Strategically placed trees act as goalies or line backers, catching embers before they reach your home.

Oaks on a neighboring property offer an ember shield for this fire defensive Tujunga Garden

The Right Place

Now that you know how the process works, you can probably guess a thing or two about the “right place.” The most firewise, protective place for trees is:

  1. Physically-Distanced: Fully-grown canopy should be 10 feet from chimneys.
  2. Power-Free: Ensure distance between full-grown tree canopy and power lines.
  3. Ladder-Free: Distance canopies from structures like fences and taller foliage. If that foliage ignites, we want to prevent a flame height that could reach the canopy from below it.
  4. Watered: Plan to support trees with supplemental water, such as hydrozoned, low-flow, subsurface drip system on a weather based controller, or monthly deep-watering visits with a hose from June-September.
  5. Strategic: Examination of our home’s placement, topography and prevailing winds can help identify the best places for home protection.
California Native Sycamore
Coast Live Oak | Western Redbud

The Right Plant (Tree!)

Once you’ve determined the space(s) you have available and their maximum width and height, this can help guide your selection of the right tree(s). Our native trees have some advantages here, as they are best adapted to our soils and climate. This gives them an advantage in maintaining health and hydration throughout our climate cycle. Our favorite fire catchers include:

  1. Abundant Space – California Sycamore: Sycamore’s thick hardwood trunks are known to resist fire, and their large, catcher’s mitt sized leaves form expansive canopies.
  2. Ample Space – Coast Live Oak: These canopies, dense with small, leathery leaves, are ideal for catching embers. At full size, just one oak may effectively protect a full side of a home. It is also a great shade provider!
  3. Petite Space – Western Redbud: Known for its architectural branches and delicate, cotton-candy pink blooms, Western Redbud fills with silver-dollar-sized leaves in the spring. Well-hydrated leaves are defensive at a lower height.

While no plant or tree is fire-proof, these trees, when healthy, hydrated, and properly maintained, can help us reduce the chances of ember ignition, the most common source of ignition for homes. Want other options? Check out Palo Verde, Manzanita, California Black Walnut, Englemann Oak, and California Bay Laurel.

When we start to think of homes as fuel, as the National Fire Protection Council advises, we can orient our minds to the landscape design, building and maintenance actions that protect them. Those key actions include planting trees – an action that has so many additional benefits!

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