The Essential Guide to Defensible Landscapes
Fire Season is here again.
With everything else going on, one might almost forget that we are deep into the wildfire season here in California. As the wildfire threat increases through the summer months, the question always remains: How can your landscape help?
In California, over 3,629 buildings were damaged or destroyed in 2021, with three of the largest fires in history taking place in that singular year. 2.6 million acres burned over the course of 8,619 wildfires, and amazingly enough, this was a vast improvement from 2020, where the season was so severe that a State of Emergency was declared.
While 2021 was, in comparison, an improvement, there is all the more reason to increase preparedness—either in bracing for heightened risk as our summers continue to
break record temperatures and humidity lows, or to increase the downward trend in fire season losses.
Property owners are at risk, to be sure, but what can we do to minimize those risks? Is it possible to improve the defensibility of our properties by landscaping wisely?
The answer is yes.
At Madrone Landscapes, we have dealt with properties in high fire danger areas for decades. There are many ways to enhance the defensibility of a property, whether it is through plant selection and design or irrigation and water system strategies. Fire-resistant plants selections are available, but it is every bit as important that your plantings be well-spaced, properly pruned, and adequately watered in order for them to perform their fire-resistance function. Also, eliminating plants entirely from around structures may do more harm than good. Properly chosen plants can catch air-born fire embers, letting them die out harmlessly, and plants’ roots are often vital to control erosion in the event of a fire.
For ways to make your home more fire safe inside and out, see the Homeowner’s Checklist from the SLO County Fire Safe Council.
Defensible Space – Defensive Landscaping
What you plant in your yard, and where you plant it, can be just as important as how your home is built. When in the path of a wildfire, your garden and lawn can become fuel for the flames. But, by learning the different zones around your property, you can create a more fire-safe home.
Immediate Zone: 0–5 feet from the furthest attached exterior point of the structure. This is the most important zone, as fire in this area will present the greatest danger to your house. This area should be kept irrigated and clear of debris at all times.
Top Fire-Resistant Landscaping for the Immediate Zone:
- Plants up to 18 inches tall that are low-volume (not thick and bushy)
- Plants with a high moisture content, such as succulents
- Grasses a maximum of 3 inches tall
- Tree branches trimmed 10 feet up
- Area is irrigated and kept clean
- Use of rock mulch against the house (instead of bark mulch)
- Removal of all dead, dying, and diseased vegetation from gutters, ground, roof, and exterior attic vents
Intermediate Zone: 5–30 feet from the furthest exterior point of the structure. The goal of this zone is to reduce the available fuel in order to slow a ground fire. Larger shrubs and trees can be introduced here, as long as a distance that is twice their height separates them. This will prevent the “fire ladder” effect, where fires jump from one clump of shrubbery or trees (fuel) to another. Grass in this area should be mowed to 6”. This area should be kept irrigated and maintained.
Top Fire-Resistant Landscaping for Intermediate Zone:
- Succulents, small to medium shrubs
- Trees at least 10 feet apart and tree crowns 10 feet off the ground
- Lower tree limbs removed 6–15 feet from the ground
- Grass a maximum of 6 inches tall
- Shrubs separated by two times their height (a 6 foot shrub will be at least 12 feet from its neighbor)
Extended Zone: 30–100 feet, as far as 200 feet, from the furthest exterior point of the structure. The major effort here should be to thin existing vegetation and remove debris to interrupt and reduce potential fires.
Top Fire-Resistant Landscaping for the Extended Zone:
- Low to medium height plants
- Grass mowed to 18–13 inches
- Plants grouped in “islands” for water efficiency
- Dead branches, leaves, and litter removed
Landscaping in fire-prone areas should try to create a fire safe buffer—a defensive space—around your structure. On top of everything else, it is crucial to ensure there is a deliberately clear path to the structure for firefighters, ensuring both their safety and yours. Taking these measures can make it easier and safer for them to save properties from wildfires.
Fire Safe Demonstration Garden
The San Luis Obispo Botanical Garden has a Fire Safe Demonstration Garden located at 3450 Dairy Creek Road, San Luis Obispo, CA 93405. They are open daily during daylight hours. The Gift Shop and Office are open 9 am to 5 pm Tuesday through Friday.
Get more tips from the San Luis Obispo Botanical Garden’s Fire Safe Landscaping Brochure and the University of California’s Home Landscaping for Fire publication.
Make your landscape defensible. We can help! Contact us at [email protected] or (805) 466-6263.