Planning Your Landscape to Keep Your Home Safe From Wildfires

Those living in the wildland-urban interface, where homes are adjacent to large tracts of farmland, parks, or forested areas, are particularly at risk to wildfire. The amount and the type of the vegetation immediately around homes is a key factor when it comes to fire danger.

Most landscapes are made up of a number of layers of plants. Designers try to create a green, cool, environment near the home, and then reduce the amount of vegetation as you get further from the house. By the time you are 30-50 feet from the house, the idea is to begin to blend the maintained landscape back into the native landscape. Some of the desert landscapes (sometime called xeriscapes) do this very nicely, even planting native plants into the disturbed areas to help everything appear “seamless”.

This layered idea actually works well with the concept of “defensible space”. “Defensible space” can be thought of as the landscaped area between the home and the wildland vegetation. By using the right plants, at the right density, we can create an area around our homes that can be defended in the event of a wildfire.

Grass

Grass is one element of the landscape. There are many different types of grass that may be used. When kept watered and healthy, most grasses cool the area immediately around them. Since they contain a large percentage of water, they’re basically non-flammable (except in the most intense fire situations). Lawn grasses such as fescue, rye, and bluegrass accomplish this purpose quite well and can provide somewhat of a barrier to fire. Annual grains (such as wheat, oats, and rye) grow well in early spring and are often planted for erosion control. Since these dry down quickly in the summer they should be mowed off so they do not become a fire hazard. Weedy grasses (non-natives) that also act this way, include cheat grass, and foxtail. They too should be mowed short to prevent them from becoming a fire hazard.

Trees

Trees are welcome in any desert landscape. They provide shade, privacy, and protection from the wind. Deciduous shade trees in general, do not cause a fire hazard. They have high moisture content, are less flammable, and provide less fuel during their dormant period. When watered properly and kept healthy they are an asset to the landscape. Evergreens provide the same benefits but may be a serous fire hazard. Volatile oils in evergreens make them extremely flammable. Dry needles can also accumulate on roofs, in gutters, and next to the home where they may ignite. For this reason, their use and especially their location in the landscape is very critical. Since evergreen trees are so flammable, they should not be planted against your home. If they are, and you intend to keep them there for a wind break or shade, at least keep the dry needles cleaned up and prune limbs that are closest to the ground. Trees considered to be fire resistant include maple, birch, redbud, aspen, poplar, cottonwood, and willow.

Shrubs and Perennials

Shrubs are generally considered a permanent part of the landscape. They are often trimmed and shaped but not cut down entirely like perennials or annuals flowers. Like trees, shrubs that are in close proximity to the home should be deciduous rather than evergreen. They should not have large amounts of dead wood nor should they be allowed to overgrow up against the house or other structures. Perennials, by nature tend to grow up in the spring, bloom, then die back in the fall. This allows growth habit allows perennials to be cut back rather close to the ground each year. By keeping them neatly cut back each year there is little “fuel” if a fire were to be in close proximity.

Flammable vegetation including evergreen trees and shrubs should be kept at least 30 feet away from homes, garages, and out buildings. This is considered a minimum amount of space needed to defend your home (defendable space) in case of a wildfire. Homeowners, for example sometimes seek privacy by constructing their homes in the middle of a juniper forest. Unfortunately, once ignited, these trees will burn hot and fast catching other nearby structures on fire. The best way to defend your home from wildfire is to plan ahead and be prepared. How you design your landscape initially, the plants you use, and how you maintain it will play a vital role in the event of a wildfire.

Utah State University Extension