OREGON STATE UNIVERSITY

Fight fire with plants? You bet.

07/20/2012

CORVALLIS, Ore. – With summer and wildfire season upon us, it's a good time to look at your yard and see if it's a fire hazard. One way to reduce the risk of a fire engulfing your house is by surrounding it with fire-resistant plants.

Such plants do not readily ignite. They may be damaged or even killed by fire, but their foliage and stems do not significantly contribute to a fire's intensity, said Amy Jo Detweiler, a horticulturist with the Oregon State University Extension Service.

In essence, they can create a living wall that reduces and blocks intense heat. Detweiler emphasized, however, that fire-resistant plants will burn if not watered and pruned.

Plants that are fire-resistant have moist, supple leaves and tend not to accumulate dry, dead material within the plant. Their sap is water-like without a strong odor. Most deciduous trees and shrubs are fire-resistant. Annuals and lawns also can be part of a fire-resistant landscape if sufficiently watered and maintained.

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 and the leaves have a strong odor when crushed. Their sap is gummy, resinous and also has a strong smell. Some have loose or papery bark. One highly flammable shrub is juniper, said Detweiler, adding that bark mulch can also easily ignite. Use gravel or decorative rock instead, she advised.

Detweiler said that conifers and other large trees that are next to your house should be pruned on the first 15-20 feet of their trunks (or to just above the lower roofline) to keep fire from reaching the house or tree tops.

She recommends selecting the following fire-resistant plants in the Pacific Northwest and other western states. Check with your local Extension office or a nursery, however, to find out which plants are suitable for your area and to avoid planting invasive ones.

The plants, accompanied by color photos, are described in a 48-page guide, Fire-Resistant Plants for Home Landscapes (PNW 590), published by the OSU Extension Service. The guide is available free online at http://bit.ly/LvLkjA, or purchase a printed copy from the Extension catalog at http://extension.oregonstate.edu/catalog/abstract.php?seriesno=PNW+590.

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, red maple, 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.