Defensible Space

California state law requires 100 feet of defensible space around homes and structures. Proper management of defensible space dramatically increases the chance of a home surviving a wildfire and provides for firefighter safety as they defend structures. Clearing defensible space does not mean surrounding homes and structures with rings of bare soil or concrete. Instead, there are guidelines for thinning existing vegetation and maintaining different vegetation densities depending on the type of plant and its proximity to structures.
Please visit the following links for more information about the 100' Defensible Space Guidelines and Resources :

California General Guidelines for Creating Defensible Space

City of San Diego Fire-Rescue Department

County of San Diego Department of Planning and Land Use

City of San Diego Brush Management Regulations: Bulletin #1 Brush Management Guide

County of San Diego Fire, Brush, and Building Information for Municipalities and Fire Protection Districts in the County of San Diego

Landscaping

Fire-wise Gardening Zones

To create a fire-safe landscape, the primary goal is fuel reduction. Landscape using the fire-wise gardening “zone” concept, which is similar to the hydro zoning approach to water-wise gardening. Fire-wise zone 1 is the area closest to your home and other structures. Fire-wise zones 2 and 3 are located progressively further away.
• Zone 1. This well-irrigated area encircles the structure for at least 30 feet on all sides, providing a defensible space for fire suppression equipment in the event of an emergency. In high fire risk areas, like canyons and ridge lines, this zone increases to 150 feet, especially on the downhill side of lots. Plantings should be limited to carefully spaced fire-resistant species. Trees and shrubs should be no closer than 15 feet, and trees should be spaced at least 30 feet (or 3 times their diameter) apart at maturity. Trees over 18 feet tall should be pruned to remove all limbs within 6 feet of the ground.  Trees less than 18 feet should be pruned to 1/3 their height. All trees should be trimmed to be kept at least 10 feet away from roof or chimneys. Shrubs should be no higher than 18 inches. All loose debris should be removed on a regular basis.

• Zone 2. This zone extends at least 20 feet beyond Zone 1 and plants should generally be low-growing, fire-resistant species and the irrigation system should extend into this section. Any trees or shrubs should be spaced at least 10 feet apart and trees over 18 feet tall should pruned to remove all limbs within 6 feet of the ground.  Trees and shrubs less than 18 feet should be pruned to 1/3 their height. All loose debris should be removed on a regular basis.

• Zone 3. This furthest zone extends at least 50’ feet beyond Zone 2 and
is a slightly modified natural area. Thin selectively here, and remove highly flammable vegetation and all loose debris on a regular basis.

Plant Selection

Things gardeners should consider when choosing plants for a fire-safe
landscape.
• Local area fire history
• Site location and overall terrain
• Prevailing winds and seasonal weather
• Property contours and boundaries
• Native vegetation
• Plant characteristics and placement (water and salt
retention ability, aromatic oils, fuel load per area, and size)
• Irrigation requirements
For more resources, visit the following websites:
San Diego Master Gardeners
California Native Plant Society
US Department of Agriculture California Natural Resources Conservation Service

Cultivate a Fire Safe Landscape 

Improper landscaping around homes in wildfire areas of San Diego County is worrisome because it can greatly increase the risk of fire damage.  The amount of defensible space around a home is directly related to a home’s ability to survive wildfire. Removal of grasses, brush, trees, and other common fuels improves the odds that the structure will survive.

State and Federal fire officials offer the following guidelines:          

Grasses: Mow grasses in low areas close to the house, garage, outbuildings, decks and trees with low growing branches. You can gradually increase the height of grass that grows farther from these places, but it should be no higher than eight inches.

Wildflowers: Tall, dense patches of wildflowers can be powerful fuel for fires, particularly when the flowers are in the dormant stage. Plant wildflowers in widely separated beds. The beds should be separated by gravel walkways, rock retaining walls or low grass areas. Do not place flowers near structures, unless beds are frequently irrigate and promptly removed when they become dormant.

Shrubs: Shrubs in wild land fires can serve as “ladder fuels,” enabling fire to travel from ground into shrubs and from there to trees. Low-growing, non-resinous varieties of shrubs should be planted in small clumps away from each other and away from trees. Do not place them directly beneath windows or vents or where they might spread under wooden decks.

Trees: Trees can be a significant source of fire brands and, when burning, can ignite nearby shrubs, trees or structures. Consult with local plant specialists on the trees to plant in your area. When planting trees, do not place them near structures and allow plenty of room between trees.

Fire-Wise Gardening Methods

Watering

• Choose the right irrigation system. While all plants will eventually burn, healthy green plants burn less quickly. Your plant selection and water availability will determine the right system for you.
• Consider drip irrigation for watering most of your landscape. It’s effective and conserves water because it targets where the water goes and how much gets there.
• Use sprinklers for lawns or turf landscaping. Drip irrigation does not work well on lawns. Sprinklers on timers ensure your lawn is getting the right amount of water to keep it healthy and fire resistant.

Maintain Your Fire-Wise Garden

• Maintain a well-pruned and watered landscape to serve as a green belt and protection against fire.
• Keep plants healthy, clean and green during the dry season and use supplemental irrigation, as necessary.
• On a regular basis, remove dead branches, leaves and pine needles from your yard. These can serve as added fuel to a fire.
• Trim grass on a regular basis up to 100 feet surrounding your home. Prune and thin shrubs, trees and other plants regularly to minimize the fuel load.
• Stack firewood at least 30 feet from your home. Never stack firewood next to your home
• Involve your gardener. If a gardener cares for your property, ask him or her to include these regular maintenance steps as part of the routine service.
• Compost your yard and garden wastes and use compost and mulch around plants, in planting beds and along walkways. Grass recycling is another way to save time and money.
• Store flammable materials, liquids and solvents in metal containers outside the home at least 30 feet away from structures and wooden fences.
• Locate LNG (liquefied Natural Gas) tanks (butane and propane) at least 30 feet from any structure and surround them with 10 feet of clearance.
• No matter where you live, always install smoke alarms on every level of your home. Test them monthly and change the batteries at least once a year. Consider installing the new long- life smoke alarms.

Local Fire-wise Gardening Resources:

The Water Conservation Garden at Cuyamaca College has a fire-wise exhibit to demonstrate how you can make your home and landscape safer from devastating wildfires.
Quail Botanical Gardens has a Landscape for Fire Safety exhibit that demonstrates fire-safe landscape plants, design, and maintenance practices.
Elfin Forest also has an award winning fire-wise garden.