Fire-Wise Landscaping

Where I garden, in Southern California, the Santa Ana winds begin blowing in October. Each fall, a high-pressure system builds over the Great Basin area, creating hot winds as it travels through canyons and desert-valley floors at speeds of up to 60 knots. In the fall of 2003, these dehydrating winds coincided with successive years of drought, which had taken their toll on woody overgrown chaparral in the foothills and canyons of San Diego County’s wildlands. These extremely hazardous conditions set the stage for the worst firestorms in California history, which burned more than 260,000 acres, took precious lives, and destroyed over 3,000 (mostly residential) structures. Houses that bordered foothills and canyons were especially vulnerable to the flames, which shot as high as 200 to 300 feet.

Many who lost their homes in those fires have already rebuilt and are seriously rethinking their landscapes, planting firebreaks around their property with plants that have fire-resistant qualities. Of all the candidates, succulents—such as aeoniums, agaves, and aloes—are perhaps the most fire resistant, simply because of the amount of moisture in their leaves. Succulent groundcovers—like the blue-gray Senecio mandraliscae ‘Blue Chalksticks’ or the smaller S. serpens, both attractive iceplants—can be used as firebreaks, with the additional benefit that they don’t accumulate dead leaves or twigs. Creepers like Sedum album ‘Coral Carpet’, which turns a beautiful reddish bronze during the winter, or the spreading Lampranthus deltoides, sporting clusters of small, rosy daisies in spring and summer, can also be used to create a fire band at the edge of native brush areas. It’s important to plant something in the firebreaks—simply clearing land without replanting can cause erosion, leaving the landscape vulnerable to flooding during winter rains.

Avoiding the use of highly combustible plants in the landscape is just as important as seeking out fire-resistant ones. Embers can travel great distances when carried by heavy winds—as far as a mile away in a firestorm with flames reaching between 100 and 300 feet—and ignite plants that have a high oil content. Many California native plants have actually evolved to be flammable. Harsh as that may seem, it’s nature’s way of controlling thick overgrowth. Plants like greasewood (Adenostoma spp.) and wild buckwheat (Eriogonum spp.) are very combustible, along with manzanita (Arctostaphylos spp.) and creosote bush (Larrea tridentata).

Yet many California natives can be recommended for use in firewise plantings, especially those that have foliage with a high mineral and moisture content. Lemonade berry (Rhus integrifolia), California wax myrtle (Myrica californica), Indian mallow (Abutilon palmeri), and flannel bush (Fremontodendron spp.) are all exceptionally attractive flowering shrubs, and firewise natives. The native coastal prickly pear (Opuntia littoralis) is also full of moisture in its fruits and foliage, and has been known to rejuvenate after a wildfire.

While information about fire-resistant landscaping is readily available to local homeowners, it isn’t nearly conclusive enough, with many plant choices left unevaluated. Although no landscape can be guaranteed safe in a firestorm like that experienced in San Diego County last year, removing flammable plants and replacing them with more fire-resistant ones is a step in the right direction. H

For more information on fire-safe planting, visit www.firewise.org

WORTH GROWING: Aloe ferox

Blooming December to March, Aloe ferox is a great firewise plant that also gives dramatic vertical appeal. The tall, bold spikes of bright scarlet, yellow, or orange blooms (there is also a rare white form) are a visual feast. A single large trunk reaching 10 to 12 feet sports a gray-green rosette of thick, spiny, succulent leaves four feet long and eight inches wide. Although the plant is moisture retentive, lower leaves should be removed as they age and turn woody.

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