Guest Column in Ventura County Star
July 10 2025
Jacqui Irwin, California’s 42nd Assembly District
John Harabedian California's 41st Assembly District
California is once again bracing for a perilous wildfire season. CalFire reports that, as of mid‑June 2025, California has already experienced 3,290 wildfires this year, burning approximately 96,994 acres. This presents a threat that is both real and escalating. Rising temperatures, early snowmelt, spring rains and prolific seasonal grass growth, coupled with Santa Ana winds and dry conditions, have extended what once was a seasonal risk into an almost year-round concern.
Homeowners and insurers both have a vested interest in strengthening structures and surrounding landscapes. Clear defensible space, fire-resistant roofing, non-combustible fencing and decks, and ember-resistant plants may all demonstrably reduce wildfire vulnerability. Insurers are increasingly incentivizing these measures through discounted premiums and some consumers are gladly complying.
The cost of making homes fire resistant can be steep. New roofing, upgraded siding, and landscape overhauls can be expensive. While these improvements may yield lower insurance rates, that savings takes years to realize and is proving difficult for cash-strapped homeowners.
The Board of Forestry’s “Zone 0” proposal would require homeowners to keep the first five feet around their walls — known as the ember-resistant zone — entirely free of combustible plants, wood chips, or even tall potted plants. In principle, this has merit as embers can travel and ignite homes via small fuel sources close to structures.
But the rule is being applied as a one-size-fits-all approach. It ignores the vast differences between Wildland-Urban Interface (WUI) areas where ember showers arrive en-masse — and dense urban settings where fires are spread less by embers and more by adjacent buildings and their composition. Applying the strict Zone 0, or even Zone 1, to a block full of apartments or condominiums seems impractical and potentially detrimental to the urban canopies that cover some of these neighborhoods.
Even well-intentioned policies can fail without flexible implementation. We’ve already seen local governments push back. In Berkeley, rules targeting combustible ground cover sparked debate, with residents seeking revisions to preserve trees that take decades to mature. Similarly, major urban areas rarely lack firefighter access, rendering extreme ember zones less critical than they might be in WUI areas.
Enforcement of Zone 0 remains another challenge. Policing a clear‑five‑feet rule across millions of homes would be a nightmare, turning fire department personnel into the Zone 0 police.
By focusing Zone 0 in areas where structures abut a wildland urban interface, and focusing on home hardening practices in the urban areas with dense infill, seems a more measured approach. The wildfire risk in California is undeniable and escalating. Large numbers of homeowners now recognize that fire resistance measures are essential, and not optional, and insurance pricing seems to be slowly adjusting to the new reality as well.
The Board of Forestry’s Zone Zero Regulatory Advisory Board has been conducting monthly meetings and workshops to solicit public input. This input should be considered in the final and addressed in future amendments. The final guidance by the Board of Forestry should provide flexibility for local enforcement and allow for alternative means of compliance. If local enforcement seeks to go beyond state recommendations, a robust process should take place to meet Zone 0 goals.
The policies being contemplated lack the recognition that not all areas are alike. When promulgating these policies, care needs to be taken so that residents are provided clear, realistic, and achievable results that reflect the actual threat to their property based on their surroundings. A one-size-fits-all approach is rarely the answer and makes little sense in this instance.
Assemblymember Jacqui Irwin represents California’s 42nd Assembly District, which includes portions of both Ventura and Los Angeles Counties; including all of Agoura Hills, Bel Air, Beverly Glen, Brentwood, Casa Conejo, Calabasas, Hidden Hills, Lake Sherwood, Malibu, Moorpark, Oak Park, Pacific Palisades, Santa Susana, Simi Valley, Thousand Oaks, Topanga, Westlake Village, and portions of Camarillo. Assemblymember John Harabedian represents California’s 41st Assembly District, which includes the cities of Bradbury, Claremont, La Cañada Flintridge, La Verne, Monrovia, Pasadena, San Dimas, Sierra Madre, and portions of Hesperia, Rancho Cucamonga, and Upland.
Letter to zone zero regulatory advisory committee
California Board of forestry and fire protection
from:
Assemblymember Jacqui Irwin, 42nd District
Assemblymember John Harabedian, 41st District
Max Moritz and Luca Carmignani
California’s proposed ban on plants near homes could be dangerously bad advice
Los Angeles Times – Guest Opinion
June 2, 2025 3 AM PT
https://www.latimes.com/opinion/story/2025-06-02/california-fire-risk-zone-0-landscaping-plants
One of the most striking patterns in the aftermath of many urban fires is how much unburned green vegetation remains amid the wreckage of burned neighborhoods.
In some cases, a row of shrubs may be all that separates a surviving house from one that burned just a few feet away.
As scientists who study how vegetation ignites and burns, we aren’t surprised by these images: We recognize that well-maintained plants and trees can help protect homes from wind-blown embers and slow the spread of fire in some cases. So we are concerned about new wildfire protection regulations being developed by California that would prohibit almost all plants and other combustible material within 5 feet of homes, an area known as “Zone 0.”
Wildfire safety guidelines have long encouraged homeowners to avoid having flammable materials next to their homes. But the state’s plan for an “ember-resistant zone,” being expedited under an executive order from Gov. Gavin Newsom, goes further by also prohibiting grass, shrubs and many trees in that area.
If that prohibition remains in the final regulation, it’s likely to be met with public resistance. Getting these rules right also matters beyond California, because regulations that originate here often ripple outward to other fire-prone regions.
Research into how vegetation can reduce fire risk is a relatively new area of study. However, the findings from plant flammability studies, as well as examination of sites where vegetation and homes survive large urban fires, highlight its importance.
When surviving plants appear scorched after these fires, it is often on the side of the plant facing a nearby structure that burned. That suggests that wind-blown embers ignited houses first: The houses were then the fuel as the fire spread through the neighborhood.
Photos before and after the 2025 Palisades fire show thick green vegetation between two closely spaced homes. The arrow shows the direction of the fire’s spread. When surviving plants appear scorched after these fires, it is often on the side of the plant facing a nearby structure that burned. That suggests that wind-blown embers ignited houses first: The houses were then the fuel as the fire spread through the neighborhood.
We saw this repeatedly in the Los Angeles area after wildfires destroyed thousands of homes in January. The pattern suggests a need to focus on the many factors that can influence home losses.
Several guides are available that explain steps homeowners can take to help protect houses, particularly from wind-blown embers, known as home hardening. Some examples include installing rain gutter covers to keep dead leaves from accumulating, avoiding flammable siding and ensuring that vents have screens to prevent embers from getting into the attic or crawl space.
However, guidance related to landscaping plants varies greatly, and some of it is bad advice.
For example, some “fire-safe” plant lists contain species that are drought tolerant but not necessarily fire resistant. When it comes to keeping plants from becoming fuel for fires, what matters more than species selection is how well vegetation is maintained and whether it’s properly watered. Location matters too: Dry, unmanaged plants under windows or near fences may ignite rapidly and make it more likely that the house itself will catch fire.
When well-watered, living plant material is heated by a nearby energy source, such as a fire, the moisture inside it must be driven off before it can ignite. That evaporation cools the surrounding area and lowers the plant’s flammability.
In many cases, high moisture keeps a plant from igniting. We’ve seen this in some of our experimental work and in other studies that test the flammability of ornamental landscaping.
With enough heat, dried leaves and stems can break down and release volatile gases. At that point, a nearby spark or flame can ignite these gases and set the plant on fire.
Even when the plant does burn, however, its moisture content can limit other aspects of flammability, such as how hot it burns.
Green, well-maintained plants can slow the spread of a fire by serving as heat sinks, absorbing energy and even blocking embers. This apparent protective role has been observed in both Australia and California studies of home losses.
How often vegetation buffers homes from igniting during urban conflagrations is still unclear, but this capacity has implications for regulations.
Many of the latest Zone 0 recommendations, such as prohibiting mulch and attached fences made of materials that can burn, stem from large-scale tests conducted by the National Institute of Standards and Technology and the Insurance Institute for Business and Home Safety. These features can be systematically analyzed.
But vegetation is far harder to model. The state’s proposed Zone 0 regulations oversimplify complex conditions in real neighborhoods and go beyond what is currently known from scientific research regarding plant flammability.
Vegetation is not monolithic. A mature, well-pruned shrub or tree with a high crown may pose little risk of burning and can even reduce exposure to fires by blocking wind and heat and intercepting embers. Aspen trees, for example, have been recommended to reduce fire risk near structures or other high-value assets.
As California and other states develop new wildfire regulations, they need to recognize the protective role that well-managed plants can play, along with many other benefits of urban vegetation.
We believe the California proposal’s current emphasis on highly prescriptive vegetation removal, instead of on maintenance, is overly simplistic. Without complementary requirements for hardening the homes themselves, widespread clearing of landscaping immediately around homes could do little to reduce risk and could even aggravate the danger.
Max Moritz is a Cooperative Extension wildfire specialist and an adjunct professor of environmental science at UC Santa Barbara. Luca Carmignani is an assistant professor of mechanical engineering at San Diego State University. This article was produced in partnership with the Conversation.