Fire is a natural and normal part of the west. Historically, most areas of the west burned regularly, often every five to ten years. Many communities, such as chaparral, depend on it. This does not lessen our desire not to have our homes or yards damaged or destroyed by a fire, natural or otherwise. It does emphasize the risk that most of us live with. In most years, wildfires consume large areas of the west. In recent years, there have been disastrous wildfires that have swept urban areas of both Northern and Southern California, destroying hundreds of homes and reminding us of our vulnerability.
In most parts of California, sensible landscaping must be designed to minimize the spread of fire. Certainly there is much more to fire prevention than landscape design. No landscape plan is fireproof. The choice of roofing material and the ground’s slope are probably more important. Still should a wildfire occur, the chance of your home surviving it can be increased by proper placement of plants and maintenance.
Buildings that sit above steep slopes are at the most risk. Air flow patterns can accelerate the speed and intensity of fires up these slopes. You should be particularly cautious if your house is in this situation, avoiding trees and most shrubs on the downhill side. A fire resistant ground cover would be a good choice for the hillside.
Placement of plants can be more important for fire resistance than the specific type of plants chosen. “Fire ladders” are particularly dangerous. A fire ladder is an arrangement of plants that provides a continuous fuel supply from ground level through treetop. An example would be a flammable ground cover or debris under medium shrubbery topped by trees. Generally the best way to avoid this problem is to place shrubs at a distance from trees maintaining a gap that cannot easily be jumped by flames. This is particularly important close to the house.
Also important is to maintain a fire resistant perimeter about thirty feet wide around the house. This means that within the perimeter the plants should be widely spaced and either fire resistant or at least not highly flammable. Appedix A includes list of plants in both categories.
Perhaps most the important part of wildfire defense is maintenance. Any trees that are close to the house should be trimmed so they do not overhang roofs, ideally maintaining a ten foot clearance. All debris, such as leaves and needles should be kept clear of the roof and gutters. Periodically clean debris from beneath shrubs and trees. The dry sticks, dead branches, and bark that can build up around plantings can be almost explosive in a fire.
Following these simple guidelines could save your house in a wildfire. They are mostly common sense, but it is surprising how few people follow them. There is no need to become obsessed with fire prevention or to let it dominate your landscape plans, rather keep the risks in mind as you develop your design. You will no doubt find that incorporating these suggestions is not difficult.