If you live in a wildfire-prone area, you know how devastating Mother Nature can be. The good news? You are smarter than a wildfire, and there are ways for you to prevent your home from catching fire. After all, as long as it won’t ignite, it won’t burn.
Learn how to reduce the chance that your landscape will ignite or burn the next time a wildfire comes roaring through.
- 1. Prepare your defensible space
- 2. Don’t forget fences and decks
- 3. Choose fire-resistant plants
- 4. Space shrubs and trees properly
- 5. Hardscape around the home
- FAQ about fire-resistant landscaping
- Want to learn more about fire-resistant landscaping?
1. Prepare your defensible space
What is defensible space? Defensible space is the barrier between a structure and the vegetation around it. Defensible space slows or stops a wildfire from spreading or from igniting your home.
If your property is in the path of a wildfire, this defensible space also gives firefighters a safe zone to work in to defend your home.
Cal Fire (The Department of Forestry and Fire Protection) divides a building’s defensible space into three zones:
Zone 0: Ember-Resistant Zone
(0-5 feet from buildings and decks)
If you could sum up Zone 0 in a phrase, it might be, “If it doesn’t ignite, it can’t burn.” This ember-resistant zone is designed to deprive potential embers of the fuel they need to ignite other materials, which can spread fire to the home.
Scientific testing has shown this to be the most important zone in your defensible space. Since 60%–90% of fires are ignited by flying embers, many from miles away, you want “zero” combustible materials within 0–5 feet of your home. If a flying ember lands in a properly prepared Zone 0, it won’t ignite other materials, and “if it doesn’t ignite, it can’t burn.”
The following are the current Zone 0 guidelines set forth by the California Board of Forestry and Fire Protection.
- Use only noncombustible materials in this zone: concrete, pavers, bricks, gravel, etc. (NO organic mulch material in Zone 0!)
- Maintenance is key: Clean out all dead or decaying plant material from this area: dead leaves, weeds, branches, grass, etc. This includes removing dead material and debris from your gutter, roof, deck, stairs, and any structure within this 5-foot zone. (Leaf and needle debris is one of the most common ways for homes to ignite and burn.)
- Any plants in this zone must be fire-resistant: nonwoody, well watered, and low-growing.
- Cut back all limbs that are within 10 feet of the chimney.
- Remove combustible materials from your decks (seating, cushions, planters, or other furniture) and place them inside or in another zone. Cushions, for example, provide a perfect environment for embers to ignite.
- Gates or fences within this zone should be made of a noncombustible material (ex. metal). If you have a gate or piece of fence within this zone, you don’t necessarily need to replace the entire structure. Do replace at least the portion within 5 feet of the home with a noncombustible material.
- Move waste canisters, boats, and vehicles to either Zones 1 or 2.
- Relocate propane tanks and gas canisters to Zone 2. Store these in a shed, and build a 10-foot ember-resistant radius around the storage building.
- Move firewood to Zone 2. Don’t store it on your deck.
- Final tips: In Zone 0, details are important. Wooden-handled lawn tools, brooms, and doormats are a few little things that can become a fuel source and ignite your home. Zone 0 is the most critical section of your defensible space, so pay attention to the potential fuel sources in this area.
Zone 1: Lean, Clean, and Green Zone
(5-30 feet from buildings and structures)
Remove all dead or decaying vegetation within this zone, and prevent fires from “laddering up” by maintaining spacing between shrubs and nearby trees.
- Cut away any branches that overhang the roof.
- Maintain space between trees and combustible items such as swing sets and furniture.
- Maintain at least 10 feet of horizontal space between tree branches.
- Shrubs should be a minimum of 10 feet from the edge of neighboring trees. This prevents shrub fires from acting as ladder fuels and igniting nearby trees. Also, maintain plenty of space between clumps of shrubs or vegetation. (Exact spacing recommendations vary according to the terrain. See number four for more details or contact your local fire department for area recommendations.)
- No flammable plants near windows.
- Don’t forget to clean underneath decks, stairs, or balconies. Remove all dead or decaying vegetation underneath or around these structures.
- Clean out any vegetation from underneath trees.
- There should be no dead vegetation in this zone. Remove all dead, dying, or dry vegetation (grass, plants, and weeds) in this area. Keep grass well watered and at 3 inches or less.
- All dead or dry pine needles and leaves must be removed from the lawn.
Zone 2: Reduce Fuel Zone
(30-100 feet from buildings)
The goal in Zone 2 is to reduce the amount of fuel a fire has to feed on as it’s coming toward your property.
- Mow grass no more than 4 inches tall.
- Maintain proper horizontal and vertical space between trees and shrubs. (See number four for more information.)
- Debris such as needles, bark, and leaves is permitted up to a 3-inch depth, but remove as much as you can.
- Keep a 10-foot radius of bare soil around woodpiles.
Outbuildings and propane tanks: Keep a 10-foot ember-resistant zone around all outbuildings and propane storage tanks. From 10-20 feet, remove all flammable vegetation.
Many of these instructions are free (like raking your leaves). Others will require a financial investment. Start closest to the house, and don’t hesitate to contact your local fire department if you need assistance.
2. Don’t forget fences and decks
Fences and decks are key elements in your defensible space because they are often attached to your home. As such, they can act as friend or foe if a wildfire is near.
Good fences make good neighbors. They also have an important role to play in protecting your home from wildfire. The fence around your home can either help or hurt the chances that your home will ignite.
Here are tips to protect your fence from igniting:
- The most important zone to consider is Zone 0. All fencing or gates within 5 feet of your home should be noncombustible. If you have a wooden fence attached to your home, replace at least those 5 feet with a noncombustible material like metal.
- Keep it clean. Regularly clean all debris from the slats and between the soil and the bottom of the fence. Remove climbing vines as well.
- Leave 1 inch of debris-free space between the soil and the bottom of the fence. This will help prevent rotted wood, which will ignite more quickly.
- Avoid privacy fences, if possible. Embers will easily lodge at the intersection of the horizontal and vertical supports and ignite the fence.
Your deck is your favorite place to relax, enjoy the view, or socialize with family and friends, but during wildfire season, it can be your home’s worst enemy. If your deck boards or furniture is made of a combustible material, an ember on your deck, patio furniture, or outdoor chair cushion may ignite your home.
How can you make your deck less likely to ignite?
- Keep it clean. Don’t forget to clean between the deck boards. Also, check that no debris falls between the deck and the siding on the house. Leaves and needles are easy fuel sources for flying embers.
As we’ve discussed for Zone 1, remove all dead vegetation from underneath the deck. It’s not only debris that you need to clean: Garden tools, lawn furniture, or other “stuff” that often gets thrown underneath the deck is an easy source of ignition for encroaching flames or embers.
- Replace rotted wood. Rotting wood ignites more easily.
- Build a deck enclosure or add skirting.
- Follow the spacing guidelines detailed in number four, especially if your deck sits on a slope.
- Create a Zone 0 (ember-resistant zone) underneath and around the deck. (Note: Cleanliness is key. The perfect Zone 0 design can fail if it is not kept clean and free from dead organic matter and debris.)
- Add metal flashing in between the ledger board and the house. For extra protection, install a noncombustible deck board directly against the house.
- When it’s time to build a new deck, consider using noncombustible materials for the decking and joists. Fire-retardant-treated boards or other materials that have been approved by the state fire marshal also may be a good option.
Pro Tip: Move combustible deck furniture, propane tanks, cushions, and other combustible paraphernalia to an outbuilding when fire threatens.
3. Choose fire-resistant plants
If you want to add color, texture, and function to your defensible space, fire-resistant plants are a good place to start. Fire-resistant plants aren’t fireproof: They may ignite, but they won’t contribute to the spread or intensity of the fire (as long as they’re maintained well).
Look for plants with these characteristics:
- Produces small amounts of litter, debris, or dead materials
- Stores water in stems or leaves
- Needs little watering
- Naturally high-moisture plants
- Has deep root systems that maintain soil structure and reduce erosion
- Low-growing and slow-growing
- Contains no or low amounts of resins or volatile oils
Avoid plants with these characteristics:
- Are high-maintenance
- Produce a high volume of plant litter
- High amounts of resins or volatile oils
- Require lots of water or are not drought tolerant
- Bark that comes off easily (papery or loose)
Many native plants are considered fire-resistant, but the fire-resistant plants listed below may not be available or native in your area. Ask your local Cooperative Extension Office for a state-specific bulletin on fire-resistant plants for the best options.
- Creeping red fescue
- Wooly thyme
- Yellow ice plant
- Coreopsis (annual or perennial)
- French lavender
- Hen and chicks
- Red monkey flower
- California fuchsia (shrub/perennial)
- Cotoneaster (shrub or ground cover, depending on the variety)
If you have any of the plants below in your lawn, consider removing them. These are a few plants that are NOT fire-resistant:
- Jubata grass
- Pampas grass
- Conifers, including pine, yew, cypress, spruce, cedar, fir (Two notable exceptions are western larch and ponderosa pine due to their thick bark and high-moisture foliage. Must be properly spaced.)
Key takeaway: A well-designed fire-resistant landscape is only as safe as the level of maintenance you provide. Plant litter that remains on the ground or plants that are not properly watered can turn into a liability. Maintenance is key.
Set up a maintenance schedule for yourself (or for your landscaping crew) to ensure your landscape is continually maintained and fire-safe.
4. Space shrubs and trees properly
It’s important to consider both the vertical and horizontal spacing of your shrubs and trees. Keeping proper space between plants prevents fires from “laddering up” and moving higher, possibly starting a crown fire.
Crown fires travel quickly through tree canopies, jumping from one tree to the next, especially in the presence of strong wind. These fires are usually more intense than surface fires and harder to contain. It’s usually easier to defeat fires that are on the ground rather than in treetops, so space your shrubs and trees properly.
Vertical spacing is the vertical distance between the ground and the lowest tree branches.
- Keep at least 6 feet of vertical space between the ground and the lowest tree branches.
- If you have shrubs underneath trees, use this formula: Shrub height x 3 = minimum vertical clearance between the shrub and the tree. For example, if your shrub is 4 feet tall, the formula looks like this: 4 x 3 = 12. So, keep at least 12 feet of vertical space between the top of that 4-foot shrub and the lowest tree limb.
Horizontal spacing is the horizontal distance between each tree or shrub.
How far should you space them? It depends on the slope.
Flat to minimal slope: (Less than 20%)
- Trees: At least 10 feet of horizontal space.
- Shrubs: Shrub height x 2 = minimum horizontal spacing (Ex. 4 x 2 = 8 feet between shrubs)
Minimal to moderate slope: (20%-40%)
- Trees: At least 20 feet of horizontal space.
- Shrubs: Shrub height x 4 = minimum horizontal spacing (Ex. 4 x 4 = 16 feet between shrubs)
Moderate to steep slope: (>40%)
- Trees: At least 30 feet of horizontal space.
- Shrubs: Shrub height x 6 = minimum horizontal spacing (Ex. 4 x 6 = 24 feet between shrubs)
Keep these principles in mind as you’re creating your defensible space in Zones 1 and 2.
5. Hardscape around the home
Firescaping is the marriage of the living (softscaping) and non-living (hardscaping) components around your home. Together, these elements are more effective than the sum of their parts and create an effective defensible space around your home.
Most homes come with hardscaping when you move in: Driveways, walkways, and stone or brick pathways are all examples of hardscaping you probably already have on your property.
This non-living element can be especially useful in Zone 0, the ember-resistant zone, since this zone consists of only non-combustible materials.
In addition to your driveways and walkways, here are other ways to incorporate hardscaping into your defensible space:
- Retaining walls and steps going up a hill
- Stone seating walls
- Concrete, gravel, or paver walkways against the home (zone 0)
- Brick chips, gravel, and rocks as mulch
- Raised landscaping beds
- Patios and decks
FAQ about fire-resistant landscaping
Glad you asked. Creating defensible space around your home is only half of the equation. Hardening your home is the first thing you should focus on, even before you think about your defensible space.
Check out this resource from Cal Fire. You’ll find a Low-Cost Retrofit List, Wildfire Home Retrofit Guide, and a survey with a custom checklist on how to create a firewise structure.
In Zone 0, only non-combustible materials can be used. So, this means you’ll need to choose inorganic mulches, such as rocks or pebbles for areas within 5 feet of your home.
In Zones 1 and 2, however, some organic mulches are okay. Composted wood chips are the best choice in these areas but use them strategically. You want to break up areas that have mulch; you don’t want a continuous row as this can continue the line of fire should it ignite.
For example, think about creating flower bed “islands” that are mulched but bordered by inorganic materials like rocks. If the mulch does ignite and start to spread, the rocks bordering the bed will stop the fire from spreading beyond that bed.
Not at all. Your imagination is your only limit to what your landscape can become. Some homeowners choose to create what some would consider a bland defensible space with little color, texture, and greenery. There are others, however, who incorporate terraced ornamental beds, for example, with loads of color and texture that brightens and adds value to their home.
If you need to create a defensible space but don’t want to tackle a design project on your own, look for local landscape designers who specialize in fire-resistant landscaping. Find a firm that has experience creating beautiful and functional fire-safe landscapes that add aesthetic and practical value to your property.
Fire-resistant landscaping isn’t about giving up the lawn you love. It is about re-thinking the space around your home to create a landscape that will resist or slow ignition if or when a fire occurs.
Want to learn more about fire-resistant landscaping?
Here are some other resources to help you create a fire-resistant barrier around your home.
If you need help to design or maintain your defensible space, contact one of our local lawn care professionals. They are locals who create defensible spaces around their own homes, so they’re well equipped to help you reach your firewise landscaping goals.
Main Photo Credit: Ulrike Leone | Pixabay