A resilient, firewise landscape design uses sustainable practices, hardscape, and plant selection hand in hand to reduce the risk of fire in the defensible space zone, while creating a beautiful garden.
Ladder Fuels: the distance between the understory plant and lowest tree limb is recommended to be 3x the understory plant height
Sustainable Landscape Practices will keep plants healthy and so less prone to ignition. At the same time, sustainable practices can lower maintenance needs, and encourage native wildlife to enter the garden to pollinate and provide other ecosystem services:
Fire resistant landscaping is landscape design that integrates proper plant selection, placement and maintenance, with features such as retaining walls, paths, fencing, and open areas to reduce a property’s vulnerability to wildfire. Careful planning and design will reduce the possibility of ignition, lower fire intensity, and slow the spread of fire – all factors which will increase a home’s survivability during a wildfire. As a reminder, however, review and follow the recommendations in the Home Hardening section (to come https://sonomacounty.ca.gov/General-Services/Energy-and-Sustainability/Benefits-of-Sustainability/Construction-Hardening/) as a critical first step in protecting your property.
Creating a sustainable, fire-wise garden takes careful planning, and it may be helpful to consult with a local landscape professional knowledgeable about the techniques described in this section.
Within the 100’ defensible space, “fuel breaks” are a vital component in firewise design. Create fuel breaks with driveways, low-water use lawns, walkways, patios, parking areas, areas with inorganic mulches such as decorative rock, and with fences or walls of nonflammable materials such as rock, brick, metal or concrete to slow the spread of fire and separate your home from ignition sources. Leaving open space around the home and within the landscape also allows firefighters leeway to fight a fire safely and effectively. While bare soil can’t burn, it is not promoted as a firewise element due to aesthetic and soil erosion concerns, although some small patches of bare earth can provide habitat for native bees.
Create fuel breaks by:
Defensible Zones & Plant Selection - Right Plant, Right Place
Within the 100’ defensible space there are typically 3 zones with different approaches to plant selection. Consider the species, height, and width at maturity when selecting new plants. Closer to the house, it’s best to reduce potential fuel for fire by choosing lower-growing plants, and within 5’ of the house it’s best to use only hardscape. (see plant list section of this website)
Focus on locally native plants, since they are best adapted to this climate, and are better able to remain well hydrated with less water than many non-native plants. A mix of at least 70% native plants provides excellent habitat for wildlife biodiversity, and allows plenty of room for other favorites.
Awareness of the micro-climate (sun, shade, wind, marine influence) and climate zone at your property will help determine plants that will remain healthy with the least maintenance. In choosing plants, it also helps to know the local plant communities of your watershed.
Avoid Invasive Species which are often dry and combustible in fire season https://www.cal-ipc.org/plants/profiles/)
Keeping plants healthy with proper seasonal pruning, irrigation and mulching is of primary importance in a firewise garden. A proper maintenance program should incorporate annual maintenance based on the life cycle of the plant and work that should be done every few years. During fire season, particularly during Red Flag Warnings, a good thorough clean up around your plants is recommended along with a good soak
Consult a licensed arborist to help maintain your trees in good health.
Most trees can be maintained to reduce ignitability, and the shade they provide can suppress weeds while retaining moisture, cooling your house and enhancing your property’s Defensible Space. Certain species such as Italian cypress, however, cannot be maintained in a way that reduces ignitability, and the buildup of dead material behind their foliage is dangerous year-round.
Remove lower limbs of trees so that no foliage is within 6’ of the ground (or 1/3 the height of the tree if it’s less than 30’ tall). Preserve single specimens or groupings of well-pruned trees, while keeping vertical spacing between lower branches and understory plants equal to 3x the height above the understory plant.
Continuous Canopy in Forests and Woodlands
Many residential areas are located within forests or woodlands, in which mature tree canopies are touching overhead. As long as there are no ladder fuels that can carry a fire from the ground up into the canopy, this intertwining canopy should be no problem. Also note that it is wise to create a break in the canopy at least 30' from the house to reduce the risk spread to the house if a canopy fire occurs. If there is enough sunlight, lower growing shrubs (to 3’) and groundcovers can be beneficial in these woodlands to provide wildlife habitat. All trees should be pruned to remove dead or dying branches, and lower branches should be pruned to 3x the height above the understory plant.
Plant Communities and Habitat
Plant Communities are groups of plants that grow together because of similar adaptations to microclimates, rainfall, soils and slopes, and other factors. Some typically found in Sonoma County are listed below. For more detail go to: https://www.laspilitas.com/comhabit/california_communities.html
FIRE HAZARDOUS PLANTS
Highest Hazard Species
Certain fire prone shrubs and trees, like juniper, Italian cypress, pampas/jubata grass and bamboo are so combustible that they should be removed from the Defensible Space area and replaced with more appropriate plant selections. Eucalyptus trees, as well as conifers like pine, cedar, and fir trees should be removed or maintained aggressively for fire resistance.