- Author: Maggie Mah
- Contributor: Cynthia Nations
- Contributor: Lisa Erdos
- Contributor: Stephanie Erskine
The Bad News: “Fire Season” is now year-round in California. More Bad News: wildfires are no longer confined to areas with overgrown forests: homes in suburbia are increasingly vulnerable to devastation. The Good News: there are things you can do to improve the odds of your home surviving a wildfire. But please don't wait until the arrow on the “Fire Danger Today” indicator moves to yellow. Act now.
Create “defensible spaces” around your home. “Defensible space” is a term used by firefighters and means that key areas around your house have been designed and maintained to reduce the risk of fire so that firefighters will have the best chance of defending your home. Picture your house at the center of three concentric rings. Each ring is a “zone” of defensible space.
Zone #1: This area extends from the house outward to a distance of five feet.
Because most homes are destroyed when embers ignite flammable items on or near the structure, this area should be kept free of anything combustible. Check the roof, gutters, nooks and crannies around the house and under decks for dry leaves and pine needles. Relocate your woodpile away from your house, stow brooms and flammable lawn furniture somewhere safe and replace natural fiber doormats with non-flammable alternatives.
All plants—even green ones—are flammable so relocate any shrubs next to your house to suitable areas farther away. Replace wood and other flammable mulches with decorative rocks and crushed stone. Plants in this area, if any, should be widely spaced, low-growing, non-woody and herbaceous.
Zone #2: is the next circle, between 5 and 30 feet from the home.
Key words for this space are “lean, clean, and green.” “Lean” means a limited amount of vegetation with adequate spaces in between to prevent flames from climbing or “laddering.” “Clean” means the area is kept free of dead, dry plant debris. “Green” means plants in this zone receive adequate irrigation, especially during fire season. You can increase the water holding capacity of the soil by incorporating organic soil amendments before planting and by using rock mulches instead of highly combustible bark mulches.
Zone #3: is the outermost circle, the area 30 to 100 feet away from your home.
Here, the objective is to minimize fuel that would allow fire to spread inward toward structures and to inhibit flames from moving upward into the crowns of trees.
Preventive action includes removal of dead or dying trees, dead branches and piles of dry twigs and bark. Thin trees so that branches are separated by at least 10 feet. For taller trees, prune branches so the lowest are 10 feet from the ground. (Note: If your property does not extend this far, work with your neighbors to come up with a plan for mutual safety.)
Which plants to plant?
No plants are “fire proof” but there are plants that are fire-resistant. These types of plants store water in their leaves and stems and when subjected to fire conditions, can reduce the intensity with which a fire spreads by acting as “heat sinks.” Look for higher moisture plants with low levels of flammable oils and resins, an open branching habit and a relatively low volume of total vegetation. They are typically slow-growing, tidy and do well with limited watering.
Many plants native to California meet fire resistant criteria. Since they have evolved in our local environment and tend to be slower growing, they produce less flammable material, are usually low maintenance and require less water. Here are a few examples:
- Annuals: Red Maids (Calandrinia mensiesii), Mariposa Lily (Calachortus venustus), and Tidy Tips (Layla platygloss)
- Evergreen Shrubs: Bush Poppy (Dendromicon rigida), Lemonade Berry (Rhus integrifolia), Coffeeberry (Frangula californica), and California Lilac (Ceanothus-many forms)
- Deciduous Shrubs: Flowering Currant (Ribes sanguineum var. glutinosum), Snowberry (Symphoricarpos albus), Mock Orange (Philadelphus lewisii)
- Perennials: Douglas Iris (Iris douglasiana), Common Yarrow (Achillea millefolium), California Buttercup (Ranunculus californica), California Fuschia (Epilobium canum), Foothill Penstemon (Penstemon heterophyllus)
- Large Shrubs and Trees: Coast Live Oak (Quercus agrifolia), Mountain Mahogany (Cercocarpus betuloides), Western Redbud (Cercis occidentalis), Western Sycamore (Platanus racemose)
For more on choosing fire-resistant plants, check the UC Cooperative Extension website.
For more on fires, defensible space and preparedness, check out these websites:
- What's Behind California's Surge of Large Fires?
- Fire in California: Defensible Space
- Wildfires: Protecting Our Homes-and Our Forests
"Firewise landscaping: Make your home safer now" was written by Maggie Mah, UC Master Gardener of San Mateo and San Francisco Counties, and published in the San Mateo Daily Journal on February 14, 2022.