Creating a “defensible space” around your home is one of the most important and effective steps you can take to protect yourself, your family, and your home from catastrophic wildfire. Defensible space is the area between a structure and an oncoming wildfire where nearby vegetation has been modified to reduce a wildfire’s intensity.
What is defensible space?
Defensible space is the area between a structure and an oncoming wildfire where nearby vegetation has been modified to reduce a wildfire’s intensity. Creating a “defensible space” around your home is one of the most important and effective steps you can take to protect yourself, your family, and your home from catastrophic wildfire.
Many people resist creating defensible space around their homes because they believe these areas will be unattractive and unnatural. With careful planning, FireWise landscaping can be aesthetically pleasing while reducing potential wildfire fuel. It can enhance beauty and property values, as well as personal safety. Many native plants are highly flammable during different seasons of the year. At such times, left unmanaged, they can accelerate the spread of a wildfire through your neighborhood, threatening homes, property, and lives.
All vegetation is potential fuel for fire regardless of if it’s naturally occurring or otherwise. Its type, amount, and arrangement have a dramatic effect on fire behavior. There are no truly “fireproof” plant species, so plant choice, spacing, and maintenance are critical to defensible space landscaping.
Where and how you plant may be more important than what you plant. However, given alternatives, choose plant species that tend to be more resistant to wildfire.
How to choose the correct FireWise Plants
General concepts to keep in mind when choosing and planting FireWise species are:
- A plant’s moisture content is the single most important factor governing its volatility. (However, resin content and other factors in some species render them flammable even when the plant is well-watered.) Conifers tend to be flammable due to their oil and pitch content, regardless of their water content.
- Deciduous plants tend to be more fire-resistant because their leaves have higher moisture content, and their basic chemistry is less flammable. Also, when deciduous trees are dormant, there is less fuel to carry fire through their canopies.
In some cases, there is a strong correlation between drought tolerance and fire resistance. For example, a plant may shed its leaves or needles during extreme drought. Other drought-tolerant species may have smaller leaves or thick, succulent leaves. These plants offer less fuel or have a higher moisture content, both of which help reduce fire hazard
There also appears to be a correlation between a plant’s salt tolerance and natural fire resistance. Plants adapted to salty conditions, and grow in salty situations, may better resist burning. Plants for a FireWise Landscape Plants that are more resistant to wildfire have one or more of the following characteristics:
- Grow without accumulating large amounts of combustible dead branches, needles, or leaves (example: aspen).
- Open, loose branches with a low volume of total vegetation (examples: current and mountain mahogany).
- Low sap or resin content (examples: many deciduous species).
- High moisture content (examples: succulents and some herbaceous species).
- Grow slowly and need little maintenance (do not need frequent pruning).
- Short and grow close to the ground (examples: wildflowers and groundcovers).
- They can resprout following fire, thus reducing relandscaping costs (example: aspen).
Additional tips for FireWise landscaping
Here are some additional tips to follow when planning a FireWise landscape:
- Landscape according to the recommended defensible-space zones. The plants nearest your home should be more widely spaced and smaller than those farther away.
- Plant in small, irregular clusters and islands, not in large masses.
- Use decorative rock, gravel, and steppingstone pathways to break up the continuity of the vegetation (fuel). This will help modify fire behavior and slow its spread across your property.
- Plant a variety of types and species. Besides being aesthetically pleasing, this will help ensure a healthier forest by reducing insects and diseases. Healthy, vigorous, thinned forests can better resist catastrophic fires than unhealthy ones with insect and disease problems.
- Prioritize the plants you wish to save in the event of drought and water rationing. Provide supplemental water to those nearest your home, perhaps using “gray water.”
- Mulch to conserve moisture and reduce weed growth. Mulch can be organic (wood chips or small bark pieces) or inorganic (gravel or rock).
- Avoid mulches that can easily carry fire like pine bark, thick layers of pine needles, or other materials that can easily carry fire.
Maintaining FireWise Landscapes
A landscape is a dynamic, constantly changing system. Plants considered “fire-resistant” and that have low fuel volumes can lose these characteristics over time. Your landscape, and the plants in it, must be maintained to retain their FireWise properties.
Be aware of the growth habits of the plants on your land and of the changes that occur seasonally. Keep a watchful eye for the need to reduce fuel volumes and fuel continuity. Here are some maintenance tips:
- Remove annual, herbaceous plants after they have gone to seed or when the stems become overly dry.
- Rake up and dispose of the litter as it builds up over the season.
- Mow or trim grasses to a low height within your defensible space. This is especially important as they begin to cure and dry.
- Remove damaged plant parts by snow, wind, frost, or other agents.
- Timely pruning is critical. It not only reduces fuel volume but also maintains healthier plants with more succulent, vigorous growth
