Fire Safe Landscaping

Fire Safe San Mateo Firewise Firesafe Landscaping

A fire safe landscape isn't necessarily the same thing as a well-maintained yard. A fire safe landscape uses fire resistant plants that are strategically planted to resist the spread of fire to your home.

The good news is, you don't need a lot of money to make your landscape fire safe. And you will find that a fire safe landscape can increase your property value and conserve water while beautifying your home.

Choose Fire Resistant Plants and Materials

Check your local nursery, landscape contractor or county extension service for advice on specific fire resistant plants that are suited for your environment, and help to plan you landscape.

"Firescaping"

"Firescaping" is landscape design that reduces house and property vulnerability to wildfire. The goal is to develop a landscape with a design and choice of plants that offer the best defensible space and enhance the property. The ideal is to surround the house with things that are less likely to burn. It is imperative when building homes in wildfire prone areas that fire safety be a major factor in landscape design. Appropriate manipulation of the landscape can make a significant contribution toward wildfire survival.

Firescaping integrates traditional landscape functions and a design that reduces the threat from wildfire. Itdoes not need to look different than a traditional design. In addition to meeting a homeowner’s aesthetic desires and functional needs such as entertaining, playing, storage, and erosion control, firescaping also includes planting for fire safety, vegetation modification techniques, use of fire safety zones, and defensible space principles.

Firewise Landscaping: Part 1

 

Firewise Landscaping: Part 2

 

Firewise Landscaping: Part 3

 

Fire-Safe Landscaping Considerations

Photo of fire-safe landscaping.

Healthy lawn, ground cover, and perennials form a greenbelt in the home defense zone. Plants that are green and lush give better protection. If regularly watered and maintained to eliminate the accumulation of dry plant litter, these plants will be far less likely to carry fire to your home.

Irrigation Is Critical

While all plants will eventually burn, healthy ones with a high moisture content will be more difficult to ignite. Drip irrigation systems are effective and conserve water because they target where the water goes andcontrol the quantity. Use sprinklers for lawns and ensure that your lawn is getting the right amount of water to keep it green, healthy, and thereby fire resistant.

The home defense zone can contain the occasional individual shrub or tree that is located at least 10 feet from the house. By grouping plants of similar height and with similar water requirements, you can create a landscape mosaic that uses water more efficiently and is more likely to slow the spread of fire.

Fire Resistant Plants

See our list of Fire Resistant Plants for specific species recommendations in San Mateo County.  Some landscape plants are described and marketed as fire resistant. It is important to remember that, given certain conditions, all plants can burn regardless of how they are classified. In general, select plants that are low growing, open structured, and less resinous. However, how your plants are maintained and where they are placed is as important as the species of plants that you choose. Cultural practices and landscape management (e.g., pruning, irrigation, and cleanup) have a greater impact on whether or not a plant ignites than does the species. When choosing plants for a fire safe landscape, select those with the following characteristics:

  • High moisture content in leaves (as these ignite and burn more slowly).
  • Deciduous trees are generally more fire resistant than evergreens, because they have higher moisture content when in leaf.
  • Little or no seasonal accumulation of dead vegetation.
  • Open branching habits (as they provide less fuel for fires).
  • Fewer total branches and leaves (again, less fuel for fires).
  • Slow growing, so less pruning is required (to keep open structure as noted above).
  • Nonresinous material on the plant (i.e., stems, leaves, or needles that are not resinous, oily, or waxy). Junipers, pines, spruces, and firs are resinous and highly flammable.

How To Plant and Maintain Vegetation

Healthy lawn, ground cover, and perennials form a greenbelt in the home defense zone. Plants that are green and lush give better protection. If regularly watered and maintained to eliminate the accumulation of dry plant litter, these plants will be far less likely to carry fire to your home. While all plants will eventually burn, healthy ones with a high moisture content will be more difficult to ignite. Drip irrigation systems are effective and conserve water because they target where the water goes and control the quantity. Use sprinklers for lawns and ensure that your lawn is getting the right amount of water to keep it green, healthy, and thereby fire resistant. The home defense zone can contain the occasional individual shrub or tree that is located at least 10 feet from the house. By grouping plants of similar height and with similar water requirements, you can create a landscape mosaic that uses water more efficiently and is more likely to slow the spread of fire.

Use Noncombustible Materials

Use masonry, gravel, or stone walls to separate plant groups, thus adding to the variety and improving the fire resistance of your landscape. Another way to break up fuel continuity is to use decorative rock, gravel and stepping stone pathways, cement driveways and walkways, and retaining walls as your landscape’s “hardscape” that is less flammable. Replace bare, weedy, or unsightly patches near your home with ground cover, rock gardens, vegetable gardens, and fire resistant mulches.

Mulch Conserves Moisture But Also Burns

Carefully choose the location of plants or garden beds that will need mulch. Mulches are valuable because they conserve moisture, reduce weed growth, and also cover up weed cloth. However, be careful not to use too much bark mulch in garden beds near your home or outbuildings. In general, fine (less than 1⁄4 inch particles) or stringy mulches ignite and burn more rapidly than larger chunks. When exposed to fire, thick mulch layers (greater than 2 inches deep) tend to smolder and are difficult to extinguish. Do not use wood or bark mulches within 3 to 5 feet of the house. Instead consider colored rock or other less flammable material.  Read an important study on the relative fire resistance of different mulches.

Where To Plant

Avoid putting plants in the following locations to minimize the movement of fire from vegetation to the home:

  • adjacent to the siding
  • under vents or eaves
  • tree limbs over the roof
  • under or near the deck

 

Plant and Tree Spacing

The spacing between grass, shrubs, and trees is crucial to reduce the spread of wildfires. The spacing needed is determined by the type and size of brush and trees, as well as the slope of the land. For example, a property on a steep slope with larger vegetation requires greater spacing between trees and shrubs than a level property that has small, sparse vegetation. 

Vertical Spacing 

Remove all tree branches at least 6 feet from the ground. 

Allow extra vertical space between shrubs and trees. Lack of vertical space can allow a fire to move from the ground to the brush to the tree tops like a ladder.

To determine the proper vertical spacing between shrubs and the lowest branches of trees, use the formula below.

Minimum Vertical Clearance diagram.

Example: A five foot shrub is growing near a tree. 3x5 = 15 feet of clearance needed between the top of the shrub and the lowest tree branch.

Horizontal Spacing 

Horizontal spacing depends on the slope of the land and the height of the shrubs or trees. Check the chart below to determine spacing distance.

Minimum Horizontal Clearance Diagram.


The information contained on this page is derived from several print and online sources:

  • University of California Publication 8228.  Home Landscaping for Fire.  2007.  University of California, Davis.
  • http://www.readyforwildfire.org/ Wildfire is Coming: Are You Ready.  CAL FIRE.  2012.  
  • Urban Forestry Associates.  Ray Moritz, Urban Forester and Fire Ecologist.