Hero Image

Maintenance: Stay on Garden Chores to Boost Fire Resistance


General tools

When it comes to creating defensible space, the significance of proper plant and landscape maintenance cannot be overemphasized. Poorly maintained landscapes can easily become fire hazards – regardless of which plants are grown.

The goal of fire-smart maintenance is to reduce fuel while preserving the ecological well-being of the environment. Learn more about Earth-friendly garden care.

> Clean up
> Water/Irrigation
> Mulch
> Prune

CLEAN UP: Don't be fuelish!

Removing leaves reduces fuel load during fire season. Photo: Jim Kasper
Removing leaves reduces fuel load during fire season. Photo: Jim Kasper

Fire starts when oxygen and heat come in contact with fuel. Fuel is anything that burns. Consider all the combustible items surrounding your house: plants, wood piles, propane tanks, plastic trash bins, door mats, garden tools, arbors, trellises, and more.

• Remove dead or dry plants, grass, weeds, trees, and branches.
• Remove dead or dry leaves and pine needles from your yard, roof, and rain gutters.
• Remove and replace struggling plants.
• Make sure all plants are accessible and healthy – especially during fire season.
• Remove combustible debrison and under decks, overhangs, and fences.
• Mow grass before 10 am and not on hot or windy days.
• Use string trimmers (vs. lawnmowers) for clearing vegetation to minimize the risk of creating sparks when metal blades hit a stone.
• Do not accumulate construction materials, recreational equipment, or other debris, including dry grass beneath patio decks or elevated porches.
• Use equipment properly to keep from sparking a wildfire.
Manage common fire hazards.


WATER: A precious resource – especially when fire looms

Water is a precious resource in our drought-prone climate. Overwatering can encourage quick and excessive plant growth, increasing the fuel load on your property. In addition to adhering to general irrigation guidelines and water conservation efforts, pay attention to these fire-smart irrigation strategies.

Keep your plants well hydrated. If water availability is restricted, keep high value landscape plants, such as trees, properly hydrated and remove low value plants that are overly stressed, creating fuel in your landscape.
Keep hoses accessible for firefighters.
Clearly mark all emergency (and other) water sources.
Store an extra hose or two with emergency supplies.
• If your water comes from a well, consider purchasing an emergency generator to operate the pump during a power failure.
Keep your irrigation system in good condition by checking it regularly. Make any necessary repairs before the dry season.
• Do not wet down your property on Red Flag warning days as it depletes the water our fire departments need. Irrigate as normal.


MULCH: What is (and isn’t) fire-smart

Mulch is a layer of material spread on the soil surface. Mulch has many benefits and there are many different types. Unfortunately, mulch can be flammable, and can pose a risk to your home if ignited.

Non-combustible mulch poses no fire risk and may help deflect a fire. This includes rock and gravel.

According to a study:

  • Composted wood chips are the least hazardous organic mulch. This is considered the best choice for residential landscapes. Consult your local mulch provider to determine if your mulch is composted. Caution: these wood chips burn primarily through smoldering, which might not be noticed by firefighters during a wildfire. All the other organic mulches demonstrated active flaming combustion.

  • The most hazardous mulches are shredded rubber, pine needles, and shredded western red cedar, also known as gorilla hair.

  • Important: The thickness of a wood mulch bed, wind speed, and location of the flame and building all impact the potential of mulch to ignite and how quickly fire can spread to the structures on the property.
Mulch guidelines for defensible space zones:

Proper fire-smart use of mulch ties back to the three zones of defensible space:

ZONE 0: 0-5 feet 

Use non-combustible mulches only (stone, rock, gravel, pavers, etc.)

ZONE 1: 5-30 feet 

Use composted wood chips or medium bark nuggets, but not in a widespread or continuous manner. Although studies show that it has the slowest rate of fire spread, it is still considered a combustible material and could ignite wood siding, plant debris, and other combustible materials in contact with or immediately adjacent to the mulched bed.

Separate continuous runs of wood chip areas with non-combustible materials such as gravel, rocks, decomposed granite, or stone.

Limit depth of mulch to 2 inches deep.

ZONE 2: 30 feet+

Use larger, composted or non-composted wood chips or bark nuggets. Shredded rubber, pine needle and shredded western red cedar mulches, e.g., “gorilla hair” are the most hazardous mulches for use.  If used, the recommendation is to use in areas more than 30 feet from the house or any other structure.

Mulch depth of up to 3 inches is fine in this zone and beyond.

Embers that land in thick layers (more than 2 to 3 inches deep) tend to smolder and are more difficult to extinguish.

Burning wood mulch generates embers, increasing chances of direct flame contact spreading to structures.


PRUNE: Cut out the dead (and dried and diseased) wood

Overgrown, diseased, or dead plant material creates excess fuel that can feed the spread of fire. Reduce your risk by keeping plants and trees adequately trimmed and pruned. Learn more about pruning.

Proper pruning to reduce size creates space between the shrub and the home and can prevent flames from reaching the home. K Gideon
Proper pruning to reduce size creates space between the shrub and the home and can prevent flames from reaching the home. K Gideon

Fire-smart pruning checklist:

• Cut back woody, twiggy or overgrown shrubs that accumulate dry material (e.g. lavender).
• Cut back vines and low-growing groundcovers (e.g. ivy) to remove build-up of dry stems and dead leaves.
• Thin and reduce tree canopies to remove twiggy growth, maintain separation between trees, and reduce overall fuel load.
• Remove dead or diseased branches.
• Gently thin and trim back tree canopies to remove twiggy growth and maintain separation between trees.
• Limb up trees 6 to 10 feet from the ground or up to one-third of their height
• Avoid topping trees as this causes excessive branching, is unhealthy for the tree, and results in twiggy growth that can increase the fire hazard.
Allow adequate space between plants and trees