Extension Service Garden Hints

Plants can reduce risk from wildfire

REDMOND, Ore. – Homeowners who live on forested or range lands on the outskirts of urban areas are coming to realize that precautions can help protect their lives, homes and property from wildfire. Cultivating plants that resist fire is an important step.

Horticulturist Amy Jo Detweiler and forestry specialist Stephen Fitzgerald, of the Oregon State University Extension Service in Deschutes County, recommend creating a "defensible" space around your home. This is an area where potential fuel is modified, reduced or cleared to slow the spread of wildfire. A defensible space also allows room for firefighters to fight the fire safely.

In addition, flammable plant material in the landscape can substantially increase fire risk, Fitzgerald said.

Planting fire-resistant plants in the landscape is one of three critical steps to protect your home and property, Detweiler said. The other two are using fire-resistant building materials (such as roofing) and reducing fuels around your home (such as wood piles).

"These steps do not ensure that your home will survive a wildfire," she said, "but substantially increase the chances that it will."

Fire-resistant plants do not readily ignite from a flame or other ignition sources. They may be damaged or even killed by fire, but their foliage and stems do not significantly contribute to the fire's intensity. They can be used to create a fuel break that reduces and blocks intense heat.

Plants that are fire-resistant have moist and supple leaves; little dead wood or accumulated dry, dead material within the plant; water-like sap with no strong odor; and low sap and resin, Detweiler said. Most deciduous trees and shrubs are fire-resistant.

Plants that are highly flammable generally have fine, dry or dead leaves or needles within the plant; their leaves, twigs and stems contain volatile waxes or oils; the leaves have a strong odor when crushed; the sap is gummy, resinous and has a strong odor; and some plants have loose or papery bark.

"One highly flammable shrub often planted in home landscapes is juniper," Detweiler said. "It accumulates dead needles within the plant and has volatile oils in the foliage."

Even fire-resistant plants will burn if not well-maintained, Detweiler said. "Be sure to keep all of your landscape plants healthy with watering and pruning. Annuals also can be part of a fire-resistant landscape if well watered and maintained, as can a well-maintained lawn. Bark mulch, however, can ignite easily; gravel or decorative rock can be good substitutes."

The following fire-resistant perennials, groundcovers, trees and shrubs are adaptable to several regions in the Pacific Northwest and other western states. Check with local Extension offices or a nursery to find out which plants are adaptable to your area and to avoid planting invasive plants. Conifers and other large trees that are next to the house should be pruned to a height of 15–20 feet above the ground, or to just above the lower roof line, to keep fire from reaching the house or tree crowns.

More information, with photos of each recommended fire-resistant plant, is in OSU Extension publication PNW 590, "Fire-resistant Plants for Home Landscapes: Selecting plants that may reduce your risk from wildfire," on the OSU Extension Web site.

Groundcovers
Carpet bugleweed, pink pussytoes, kinnikinnick, rock cress, mahala mat, snow-in-summer, dianthus, garden carnation or pinks, yellow iceplant, purple iceplant, wild strawberry, dead nettle, Japanese pachysandra, creeping phlox, sedum or stonecrops, hens and chicks, creeping thyme and speedwell.

Perennials
Yarrow, chives, columbine Sea thrift, basket of gold, heartleaf bergenia, sedges, trumpet vine, tickseed, delphinium, coneflower (Echinacea), fire weed, blanket flower, grayleaf cranesbill, sun rose, daylily, corabells, hosta lily, iris, torchlily (red hot poker), lavender, blue flax, honeysuckle, lupine, evening primrose, oriental poppy, beardtongue, prairie coneflower (Mexican hat), salvia (sage), lambs ear, yucca.

Shrubs—Broadleaf Evergreen
Point reyes ceanothus, orchid rockrose, Carol Mackie daphne, cranberry cotoneaster, Oregon grapeholly, creeping holly, salal, Oregon boxwood, Pacific rhododendron.

Shrubs—Deciduous
Vine maple, serviceberry, rocky mountain maple, blue mist spirea, redosier dogwood, dwarf burning bush, oceanspray, mockorange, Russian sage, tall hedge, western sandcherry, fernleaf buckthorn, western azalea, sumac, flowering currant, hardy shrub rose, wood's rose, willow, bumald spirea, snowberry, western spirea, lilac, compact American cranberry.

Conifer trees
Western larch, ponderosa pine.

Deciduous trees
Amur maple, bigleaf maple, redmaple, horse chestnut, mountain alder, red alder, birch, Western catalpa, common hackberry, eastern redbud, flowering dogwood, Hawthorn (not European Hawthorn), green ash, European beech, white ash, thornless honeylocust, Kentucky coffee tree, walnut, American sweetgum, crabapple, quaking aspen, Western or California sycamore, chokecherry, Oregon white oak, Canada red chokecherry, pin oak, purple robe locust, red oak, mountain ash.

By: Judy Scott
Source: Amy Jo Detweiler, Stephen Fitzgerald

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