Fire is a natural part of our environment. It has many beneficial effects such as reducing fuel loads, reducing competition from plant species that are not adapted to fire, and improving regeneration in fire-dependent ecosystems. However, fire also has negative effects, especially in the built environment where it destroys structures and can seriously kill or harm those who are unfortunate enough to find themselves unable to escape or find protection from a wildfire.

The purpose of the Fire Performance Plant Selector is to reduce fire risk to homes by providing recommendations on the fire performance of plant material commonly found in the home landscape so informed decisions can be made related to Firewise landscaping.

Fire-dependent ecosystems are commonly found in regions such as California and Florida, but also can be found throughout the Mid-Atlantic, Northeastern and Midwestern regions of the United States. Wildfires can be caused by natural phenomena, such as lightning, or by humans. Regardless of whether fire is started naturally, accidentally, or deliberately, it can result in loss of personal property, or even loss of life, if hazards are not minimized.

Typically, summer weather conditions in the Mid-Atlantic, Eastern, and Northeastern regions of the United States do not support fire because of precipitation patterns. Fire potential, however, increases during drought conditions or periods of low precipitation, which can occur during the spring and fall. Winters are generally cool, damp, and not conducive to wildland fires. However, weather and moisture conditions can change quickly and should be considered at all times.

Wildfire hazards are especially prevalent at the interface of the built and natural environment. Situations that contribute to wildfire spread in the built environment include accumulation of debris on rooftops, building materials such as cedar shakes, the presence of dead and live vegetation adjacent to structures that can serve as fuel for a moving fire. All of these hazards are easily mitigated with a little effort. To learn more see: Wildfire Risk Assessment Guide for Homeowners in the Southern United States.

Proper maintenance of vegetation around structures is essential to reducing fire hazards. Examples of maintenance include removing natural debris, such as dead leaves and twigs, and evergreen needles; pruning deadwood, diseased wood and low-lying branches; and maintaining appropriate vertical and horizontal spacing between plants.  Furthermore, by properly selecting and planting species with low flammability, homeowners can reduce their risk of wildland fires. By taking appropriate precautions, a homeowner can make his or her property Firewise.  To learn more see: Firewise.

In a Firewise landscaping context, flammability refers to the ability of a plant to ignite and transfer heat and/or flames to surrounding plants or structures. Plants are flammable for different reasons; some plants are highly ignitable, but burn quickly. Other plants are not easily ignitable, but can burn for a long time once ignited. Flammability is comprised of four components: ignitability, sustainability, combustibility, and consumability.

Ignitability refers to the time to ignition once a plant is exposed to an ignition source such as an ember or flame. Sustainability refers to the duration a plant can sustain a fire. Consumability refers to the percentage of a plant consumed in a fire. Combustibility refers to the rate of spread and rate of heat (or energy) given off from a burning plant. For more information, go to: Preparing a Firewise Plant List for WUI Residents.

The following lists of precautions can help you better assess your property, landscape, and vegetation with fire safety in mind:

Locating a New Home

• Site a new house on a level part of the property. If possible, do not locate a new structure on a slope. Where slopes and cliffs exist, a new home should be sited at least 30 feet from the top of the slope or cliff. As fire moves up a slope, it heats up and dries out fuels ahead of it, thus moving the fire more quickly and contributing to increased temperature, which increases the likelihood of ignition.

Building a New Home or Modifying an Existing Home

• Use fire-resistant building materials and landscape materials that are appropriate for the level of fire risk in your region.

• Make sure your home is marked with a clear address that can be seen from the roadway.
• Make sure you have 12-15’ of overhead and side clearance in your driveway.
• Make sure you have a large enough turnaround for a fire truck because it is the largest emergency vehicle that must access your property in the event of a fire.
• Homeowners with a private well should consider having a water source that is not dependent on electricity, such as a small pond or swimming pool.
• Do not depend on exterior sprinklers to control fire or reduce risk should a fire occur nearby.  Exterior sprinkler systems do not work if there is no electricity. Also, high winds will redirect the water in directions beyond your control.
• Make sure you have a clear ignition zone of at least 30 feet from adjacent vegetation. Having 50 to 75 feet of clearance from existing native vegetation and using Firewise plant material, safety recommendations, and Firewise building materials on structures is even better.

Vegetation

• Accept the fact that all plants burn! No plant is completely fireproof.
• Look carefully at the vegetation on your property and familiarize yourself about what might contribute to moving a fire closer to your home. You do not necessarily need to know the names of each plant. Look to see if there are evergreen trees, debris or trash in the understory, or accumulations of deadwood that might contribute to ignition. Ask yourself, could trees or vegetation be removed or pruned to prevent the movement of fire and ignition of vegetation on my property?

Vegetation Maintenance

• Remove highly-flammable vegetation within at least 30 feet of all structures. Homes near mature or young pines should have a minimum fuel break of 75 feet.
• Group trees by varying size and form rather than planting trees of all the same size and form throughout your landscape. This can help to minimize the movement of fire from tree top to tree top across your landscape in the event a fire does occur.
• Remove dead, low-hanging branches on trees and shrubs.
• Maintain your plants—water them and keep them pruned properly so deadwood does not accumulate in them or on the ground below them.
• Make sure tree limbs are away from chimneys and any landscape amenities having open flames, such as barbecue pits.
• Be aware of areas on your property where debris collects and regularly clean these areas.
• Make sure tree branches do not touch or overhang utility wires. Wires that touch vegetation can ignite that vegetation.
• Have an evacuation plan for leaving your property in the event a wildfire does occur.

Landscaping

• High-moisture plants are best; succulent plants that can tolerate dry areas are even better.
• Wooden fencing should not be attached to the house. End a fence with a stone pillar or space.
• Trellises can accumulate debris. Care should be taken that they are cleaned regularly. The best scenario is to use Firewise approved construction materials.
• Care should be taken when selecting species for growing on a trellis to assure that the vegetation is not collecting debris that may increase ignitability.
• Be wary of decks that debris can accumulate on and beneath. Thick layers of dry debris beneath decks can ignite very easily and this debris tends to have higher combustion rates.
• Add 1/8-inch screen under decks to prevent fire from igniting debris beneath the deck or igniting the deck itself.
• Keep an eye on areas where debris accumulates and clean out these areas regularly. 
• Make sure risers on steps are closed so fire cannot get beneath steps and ignite them.
• Be wary of the mulch you use and where you use it.
• Use stone gravel for landscaping instead of mulch near structures. Organic mulches can be used in beds away from structures.
• Create fuel breaks with pavers, walls, and other nonburnable materials.

Plant Selection

• Plant the right plant in the right place. Dead or dying plants are more apt to ignite.
• Conduct an inventory of all plant material around your home. Even if you cannot identify the plants in your landscape, you can look for dead vegetation, dead branches, accumulations of trash or debris in plants, or trees that are planted too close to each other or that have low branches. Reducing such hazards will contribute to reduced ignition or movement of fire across your landscape.
• Avoid monoplantings. All plants can die at the same time due to disease or stress, causing a greater potential for more fuel in the landscape.
• Avoid planting all the same species of plants too closely (massing). This landscape practice results in plants outgrowing their planting space and causes the inside branches in the plants to die as they grow, contributing to increased fuel loads in the landscape and increased plant ignitability.
• Work with a knowledgeable plant nursery, garden center, Cooperative Extension specialists, or State forestry staff to select plant material adapted to your region.
• Avoid selecting and planting shrubs and small trees with thorns. Thorns can collect debris and ignite more easily.
• Use native plants better adapted to drought in the climate where you live.
• Large ornamental grasses should be cut back during dormant periods in fire-prone landscapes. Large, dead, clumping grass species ignite easily.
• Select appropriate groundcovers that have low flammability. Avoid large expanses of highly flammable groundcover that will move fire across the landscape.
• Provide proper spacing between trees and shrubs.
• Avoid invasive plants. They can take over and may be more likely to burn. They can also crowd out other plants and cause them to die. Increased fuel loads and dead plant debris contribute to increased ignitability in the landscape.
  
• If planting near foundations, select low-growing plant species (<18 inches tall) and plant at least 1 foot away from the structure.
• Plant vegetation that will have at least a minimum of a 2-foot distance from a structure when fully grown.

Known Plant Characteristics that Contribute to Increased Plant Flammability

• Drought intolerance
• Peeling bark
• Be aware that trees such as oak and beech will retain some of their leaves during the winter and spring months. These leaves have greater potential to  ignite and spread fire across your landscape. Be sure to consider where these trees are planted and how far apart they are located in your landscape.
• Select plants for appropriate cold hardiness zones.
• Avoid plants with thorns if there is the potential for nearby debris to be windblown and collect within the plants.
• Avoid planting evergreens with high concentrations of resin and tar in the leaves near structures.
  

Trees and shrubs that have the following characteristics are more desirable in a fire-prone landscape:

• High leaf moisture and low leaf oil or resin content
• Minimal litter and accumulated debris potential
• More sparsely spaced foliage
• Open, loose branching habit
• High branching above the ground surface
• Easily maintained with minimal pruning needs
• Drought resistance
  

The Fire Performance Plant Selector is a valuable tool for those who are familiar with plant material but are not familiar with Firewise principles or the fire performance of vegetation. This tool is also valuable to Firewise professionals who are not familiar with plant material, plant characteristics, and cultural requirements that can help them make informed planting and plant care decisions.

To learn to use the Fire Performance Plant Selector program in more detail, view or print the step-by-step instructions by clicking on "Help" on the left. The instructions, written or in video,  will assist you with learning how to use the Fire Performance Plant Selector. After learning to use the Fire Performance Plant Selector search features, you can click on "Using Reports" to view or print instructions related to customizing reports, printing plant lists for specific sites, or generating factsheets, complete with photographs for field use.