Wildfires prompt discussion on fire resistant gardens
by Nan Sterman
Because California has a long history of wildfires, people who live near wildlands, particularly with chaparral, often ask for "fire resistant" gardens. Of course, dead plants and dead wood should be removed, but what about live plants, native habitat and gardens?
I've heard claims of succulents being fire resistant. After San Diego's Witch Fire in 2007, I surveyed destroyed neighborhoods. What I saw was that everything burned: native and exotic, oak trees and palm trees, grass and succulent ice plant. Some may have burned sooner, some later, but eventually all plants ignited.
There are published lists of fire resistant plants for California gardens, but their reliability is questionable. One highly respected botanic garden based its list on the findings of a volunteer who put leaves in an oven to test their flammability. A local landscaper took a blowtorch to native plants, then created a list of which ones burned. Other lists are based on the observations of wildland firefighters. Most lists of fire resistant plants are cobbled together from similar sources that borrow information from each other.
Although all of these observations are a good starting point for formal research, none is scientifically valid. Nor is it conclusive enough for basing plant selections, let alone destroying acres of native chaparral, California's most extensive ecosystem and where most wildfires occur.
"The assumption is that all chaparral plants are flammable," says Rick Halsey, director of the California Chaparral Institute. "But it's all based on observations in the field. No one has tested it."
Nor has anyone tested landscape plants, says Halsey, a biologist trained as a wildland firefighter. His organization's goal is chaparral education and preservation, a large part of which is tied to fire management.
By definition, wildlands are where wildfires occur. Ultimately, the best protection from wildfires is to live in an urban area, far from embers that can travel for miles in a firestorm. If they land on something flammable, they ignite.
If you do live in or near a wildland, Halsey says your priority should be making your home fire resistant. Install fire resistant roofs, boxed eaves, double-glazed windows and ember-resistant attic vents. Seal all gaps between roof tiles. Don't connect wood fences to your home.
Remove anything flammable in the 30 feet surrounding your home. In the next 70 feet, remove all dead plant material. Leave living native plants, but thin them by half to break up continuity. This will prevent fire from spreading from plant to plant. Don't scrape or otherwise disturb the soil lest you risk invasion by annual exotic grasses. These grasses will dry out in the summer heat and act like tinder if a wildfire roars through in the fall. The same thing will happen if you scrape away all the native chaparral, so don't do it.
Nan Sterman is author of "California Gardener's Guide Volume II." She's a gardening expert, communicator and designer who has long grown an organic garden of plants that both feed her family and beautify her yard.