It might not seem like a few plants could do much to protect your home from a wildfire, but if carefully chosen and arranged, plants can be your home’s best defense. Good firescaping, or landscaping as a fire defense, can stave off a wildfire for up to several days.
How Firescaping Works
Firescaping is landscaping with the goal of preventing a wildfire from damaging your house. It’s based on designing firesafe zones, choosing fire-resistant plants, and creating spaces that slow down or stop a spreading fire by depriving it of fuel.
Some properties are harder to firescape than others. A house on a flat site surrounded by hardpan desert with few plants doesn’t need much additional firescaping.
On the other hand, if your home sits at the top of a slope facing into prevailing winds and you’re surrounded by dense conifer forest or chaparral, it’s worth putting some serious effort into your firescaping. Hot smoke flows uphill, and a fire can spread twice as fast up a 30 percent slope compared to flat ground. Add in fir trees or creosote bushes, both of which burn well, and it’s easy to see why such a site should be firescaped with care.
Basic Firescaping Zones
On the outskirts of a property, firescaping is meant to slow the spread of fire. Close to the house, it should stop the fire altogether. To achieve these goals, firescapes are divided into two zones:
Zone 1 – This is usually the entire area within 30 feet of the house, but in highly fire-prone locations, it can extend up to 50 feet. In this zone, you’ll want to remove all dead or dry plants, keep tree branches trimmed back, create gravel or rock gardens, and plant only highly fire-resistant plants.
Zone 2 – The is the area from 30 to 50 feet from the house. Here you have a little more flexibility in what you plant, but you still need to choose plants that are somewhat fire-resistant, keep shrubs thinned, and keep tree limbs trimmed to at least 10 feet off the ground.
More than around 50 feet from your home, the focus should be on controlling erosion and promoting a diversity of native plants. Ideally, any approaching wildfire should die out or slow down dramatically here.
The Principles of Firescaping
Following some basic guidelines will help you create a fire-resistant landscape even if you’re not an expert gardener. Choose plants that won’t add fuel to an oncoming fire, space your planting beds to prevent fire from spreading, and keep your landscape clean and healthy to help it stand up to heat.
Keep Fuel Away from the House
In Zone 1, near your house or other structures, landscaping choices are critical. Within 5 feet of your house, use only non-combustible material such as pavers or gravel and low-growing, fire-resistant plants such as turf grass or flowers. Keep composted wood chips out of this area. This material smolders rather than burns and can pose a fire hazard you don’t notice until it’s too late.
Anything you plant elsewhere in Zone 1 should be highly fire-resistant. These plants might burn up completely, but they don’t create flames that could spread. They also catch and extinguish firebrands, or burning material falling from elsewhere.
Focus on native plants that have evolved to withstand the wildfires in your area. Choose low-growing species that retain water and contain little oil or resin. Deciduous trees, which hold more water and provide less fuel than evergreens, are good bets. Slow-growing plants with moist, soft leaves are better than fast growers with leathery leaves.
A few good picks are turf grass, most vegetables, cacti and succulents, periwinkle (Catharanthus roseus), star jasmine (Trachelospermum jasminoides), and oleander (Nerium oleander). Ice plant (Aizoaceae) is a particularly good succulent choice.
For Zone 2, try California lilac (Ceanothus), ivy geranium (Pelargonium peltatum), sage (Salvia officinalis), yucca, and lantana.
Avoid both conifer and broadleaf evergreens, particularly pines, spruce, fir, cypress, juniper, rhododendron, and eucalyptus. The oils and resins these trees produce make excellent hot-burning fuel. Ornamental grasses and climbing plants, particularly honeysuckle, are best avoided.
So are scented plants, which get their scent from volatile oils that ignite easily. Even some palms, such as Mexican fan palm (Washingtonia robusta), Mediterranean fan palm (Chamaerops humilis), and date palm (Phoenix dactylifera) are too flammable to be used in firescaping.
Give Your Plants Space
Where you put each type of plant is as important as the plant species itself. Plant trees such that when they reach their mature height, their canopies will be at least 10 feet apart and their limbs at least 10 feet away from your chimney, the roofs of smaller buildings, and power lines.
Create island planting beds with plenty of space in between. This helps slow the spread of fire. Keep vertical layers of plants well separated to prevent “fuel ladders,” where flames spread from shorter plants to taller ones. For example, use groundcover plants under trees rather than shrubs or tall flowers.
To add beauty to your landscape and help it withstand fire, apply a 3-inch layer of mulch to your flowerbeds and around trees and shrubs. Mulch holds moisture in the soil, which slows down the spread of fire. It also controls soil temperatures and weeds, so plants stay healthier and will be less likely to burn. Only non-combustible materials are safe with 5 feet of the house, but outside that, other common mulches such as pine bark or leaf litter are acceptable.
Find out where firefighters would access your property if need be and keep that area clear of vegetation.
Create Fuel Breaks
A vital component in every firescape design, “fuelbreaks” are buffer zones designed to deprive a spreading fire of fuel in order to slow its spread. Any area with little combustible material can work.
Functional hardscaping features such as masonry patios, driveways, and walkways are often the most practical options. A lawn is a reasonably good firebreak, but if turf grass is too thirsty for your drought-prone area, try a groundcover or low-growing native grass instead. These are easier to keep green throughout the fire season.
Beyond this, a little creativity goes a long way. Consider creating a rock garden with a few artfully arranged boulders surrounded by gravel mulch or an artificial dry streambed. A line of riprap can also work.
If your home could use a little more privacy as well as fire protection, build a wall made of brick, cement or another non-combustible material. Water features, such as ponds and streams, are also helpful for stopping fires. A simple reflecting pool could go a long way toward protecting your home.
While bare ground does slow down fire, it’s not recommended in firescaping because it contributes to erosion.
Keep it Green
A healthy landscape is less vulnerable to fire. To keep yours healthy, regularly remove debris on the ground such as fallen leaves and branches. Trim back tree branches or other plants that threaten to overhang your roof. Prune your trees and shrubs using the approach recommended for the species. Incorrect pruning or worse, shearing, causes plants to produce faster, but weaker growth, making them more flammable.
Keep your landscape well irrigated. Drip irrigation, while environmentally friendly, doesn’t keep plants’ leaves wet enough to resist heat. When a wildfire is approaching, you might not have the water pressure you need to wet down your planting areas, so water regularly. If frequent droughts in your area make this impractical, base your landscape on features that don’t need much watering, such as rock gardens.
An approaching wildfire is always worrying, but if you take the time to firescape your property, you’ll have less to worry about. Choose low-fuel native plants, get creative with non-combustible materials such as pavers and gravel, and keep up on maintenance and you can have a landscape that’s beautiful, drought-resistant, and protects your home from wildfire.