The Essential Guide to Defensible Landscapes
Fire Season is here again.
As we cope with the grave threats to public health from the COVID-19 virus and its surreal, devastating effects on our culture, one could almost forget that we are deep into the wildfire season here in California. People are experiencing a whole new level of home life now, both in- and out-of-doors. But as the wildfire threat increases through the summer months, the question remains: How can your landscape help?
In California, over 10,000 buildings were destroyed in 2020 and more than 30 civilian lives were lost. 4.2 million acres burned, the most in a single year since CalFire began keeping records, and more than the previous three years combined. A State of Emergency was declared.
It’s a sobering reminder of the threat posed by living close to nature, as record heat and low humidity continue to intensify by the year.
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.
ZONE 1 Garden Zone: 0-30 feet from the outside walls of the building – 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 Zone 1
- 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
ZONE 2 Greenbelt/Fuel Break: 30-50 feet from 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 Zone 2
- Succulents, small to medium shrubs
- Trees at least 10 feet apart and tree crowns 10 feet off the ground
- Grass a maximum of 6 inches tall
- Shrubs separated by two times their height, so a 6 foot shrub will be at least 12 feet from its neighbor
ZONE 3 Transition Zone: 50-100 feet from structure – The major effort here should be to thin existing vegetation and remove debris. Grass should be kept at 18”.
Top Fire-Resistant Landscaping for Zone 3
- Low to medium height plants
- Plants grouped in “islands” for water efficiency
- Dead branches and leaves removed
ZONE 4 Native or Neutral Zone: 100+ feet, depending on conditions – The primary goal of this area is to reduce fuel buildup by mechanical clearing or occasional prescribed fires.
Top Fire-Resistant Landscaping for Zone 4
- Grass mowed to 12 inches
- Vegetation thinned and ground kept free from litter
Landscaping in fire-prone areas should try to create a fire safe buffer – a defensive space – around your home. The home’s roof and gutters should also be cleared of any plant materials like leaves and pine needles. Taking these measures can make it easier and safer for firefighters to save homes 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.