Firewise Landscaping – Piedmont Master Gardeners

Introduction

Recent news of destructive wildfires in California made us more aware of the danger of fires that spread rapidly and lead to extensive damage. Warmer temperatures and changing precipitation patterns increase the threat of drought conditions, which has led to more intense and frequent wildfires nationally. Although Virginia is not considered a high-fire-risk zone, fires do occur in our region, sometimes with disastrous consequences. Human activities are responsible for about 90% of all fires, and in Virginia, escaped debris burning (such as yard waste or trimmings), malfunction of electrical wiring or equipment (e.g., stoves, ovens, dryers), smoking material, and lightning strikes are the most common causes of fires.

Firefighter working to contain a dangerous wildfire; photo courtesy of Pixabay

What is Firewise Landscaping? Why is it important?

For many people, a home is their greatest investment, so incorporating fire safety concepts to make a home and yard more resistant to wildfires is judicious, no matter where you live. Homes are exposed to fire in three different ways: 1) Embers from burning debris, which can travel up to a mile away from the source; 2) Radiant heat given off by materials that are burning; and 3) Flame impingement, or the transfer of heat by direct exposure to burning flames.

Firewise landscaping is the intentional design and maintenance of residential yards to make them less susceptible to damage from wildfires. Homeowners can create “defensible space” around their own home to reduce its vulnerability to dangerous fires, while also making it possible for firefighters to effectively fight any fires that do break out. This article shares recommendations for fire risk mitigation, so you can determine what steps you might want to implement in your residential landscape.

Firewise landscape design considers both the vertical and horizontal arrangement of vegetation. A fire usually climbs trees like a ladder, so removing branches and other plant material close to the ground that tend to burn upward is important. This can help prevent flames from reaching the crown of a tree. Flames also spread laterally, so providing adequate spacing between plants is important as well. This can help to break up horizontal fuel continuity to slow down the spread of fire.

Home with masonry paths surrounding exterior walls (instead of shrubs), recommended for fire safety; photo courtesy of Pixabay

Zones and Methods of Firescaping

Fire safety experts refer to several major “zones” around a home. In high-fire-risk areas where wildfires occur more frequently, no combustibles (flammable material) should be situated within 5 feet of a residential structure (zone 0), especially near vents or under eaves. General recommendations for residential structures, even those not in high-fire-risk areas, include creating a “home defense zone” that extends 30 feet from the outside walls of a residence (zone 1). Ideally, any vegetation in this zone would be well-pruned single specimens with sufficient space between each plant. Trees should be at least 10 feet from the roof and any chimneys. Beyond that area, a “reduced fuel zone” would extend 70 more feet (100 feet from the house) or up to the property line (zone 2). In this home ignition zone (HIZ), shrubs, trees, and brush should be carefully pruned and thinned out to discourage the spread of fire. In more densely populated urban or suburban areas with smaller lots, neighborhood awareness and cooperation can lead to the establishment of “firewise communities” that apply the basic reasoning of those zones.

Suburban home with trees and shrubs next to exterior walls, which provide fuel for burning embers or a fire; photo courtesy of Pixabay.

Of course, it’s not possible for every home to be in strict compliance with the fire safety zone guidelines. If your existing home is in a wooded area, for example, it may not be prudent or cost-effective to cut down many mature trees, but you might be able to selectively prune or even thin out some of those trees. Being aware of the recommendations in this article can help every homeowner make landscaping choices that are mindful of key strategies for fire-resistant landscaping. Those foundational principles include the following:

Defensible space – As noted above, landscape design that respects careful vegetative management in zones surrounding a home can help prevent or reduce the dreadful consequences of unexpected fires.
Low-flammability vegetation – These characteristics are typical of drought-tolerant plants: high moisture content, open-growth habit (more space between branches), compact shape, slow-growing species, thick (unpeeling) bark, and non-resinous material (low levels of oily sap) tend to be more fire-resistant. Note that healthy deciduous shrubs are usually somewhat fire resistant, but no plant is completely fire-proof.

Tile patio with masonry walls adjacent to home, following recommended guidelines for firescaping; photo courtesy of Pixabay

Firebreaks – Sections of open land, well-watered turfgrass, or landscape elements that are non-combustible, such as patios and hardscape features with masonry, gravel, or stone can slow down or perhaps even stop a fire from spreading.
Responsible maintenance – Leaf litter, weeds, and vegetative matter (e.g., dead branches and twigs, leaves, needles) should be cleaned up in residential yards on a regular basis, so as not to provide any additional fuel for fires. Rain gutters and outdoor areas beneath decks and porches should also be cleared of debris, and firewood should be stored at least 30 feet away from residential structures.

Dense vegetation close to this rural home could accelerate a wildfire; photo courtesy of Pixabay

Siting, pruning, and thinning – Trees should be at least 10 feet apart and pruned appropriately (a minimum of 6 feet from the ground for the lowest branches). Shrubs should be spaced properly: at least 3 times their height away from any tree and twice their height away from each other.

Many homeowners use mulch made of tree bark, but that’s highly flammable; photo courtesy of Pixabay

Special note: Many homeowners use tree bark mulch to reduce weed growth in garden beds near their homes. Unfortunately, dry organic mulch is quite combustible, especially shredded hardwood, recycled rubber, and pine needles. Homeowners may want to consider using non-flammable alternatives, such as decorative rock or gravel in garden areas near any existing structures.

Fire-Resistant Plants

Typically, gardeners select plants based on their aesthetic value and contribution to the overall appearance of property surrounding their homes. In recent years It has become important to create healthy landscapes that contribute to a sustainable environment. As such, many of us prefer native, non-invasive plants that are well-adapted to local conditions and species that support wildlife. Fortunately, the resources included in this article suggest plants and trees that are both native and that support firewise landscaping. Another critical consideration (sometimes neglected) is whether those plants might readily ignite when exposed to embers or flames.

Large trees, including resinous evergreen species, surround this home, which could be hazardous if a fire breaks out; photo courtesy of Pixabay

Many excellent resources with detailed lists of fire-resistant plants are available online. These sources are good starting points when you choose new or replacement trees, shrubs, ground cover, or ornamentals appropriate for your plant hardiness zone. In addition, knowing which plant species are pyrophytic, or highly flammable, will help you understand which choices to avoid.

Homeowner Responsibility

We take pride in making our homes and yards attractive. Therefore, we want to ensure that our property is secure and safe from potentially disastrous fires. Building understanding of firewise landscape design can help you make informed decisions that will protect your valuable home investment from fire damage. Plus, sharing that knowledge with neighbors can go a long way toward fire risk mitigation in your local community.

Resources

Building Firewise : Virginia Department of Forestry

https://dof.virginia.gov/wildland-prescribed-fire/wildfire-preparation/protect-your-property/

NFPA – Firewise USA® (administered by NFPA® and co-sponsored by the USDA Forest Service and National Association of State Foresters)

Fire-Resistant-Landscaping-for-Your-Home.pdf (designed for suburban homes)

Fire-Smart Landscaping For Enhanced Wildfire Safety | CAL FIRE (CA)

Home Landscaping for Fire (CA)

Preparing Home Landscaping – UCANR Fire Network (CA)

Landscaping Tips to Help Defend Your Home from Wildfire (CA)

SAFER (Sustainable And FirE Resistant) Landscapes (CA) Wildland Urban Interface

Selecting Firewise Plants – Surviving Wildfire (Utah)

Fire Resistant Landscaping Plants (NJ)