Firewise Landscaping

Oregon’s Fire Season used to run 4 months, now it is running 5 months. Urban house fires can occur year around, starting indoors, engulfing a house and then spreading to neighboring homes. What can you do to protect your dwelling and out-buildings in the event of a fire?

Create Zones of Protection around your house and other buildings

  1. The first zone of protection is within 5 feet surrounding your buildings. OSU Extension Service recommends that you have no plants or flammable mulch materials in this area adjacent to your home. They recommend that you use hardscapes such as driveways, sidewalks and gravel mulches bordering your buildings. This also caution about attaching wooden fences or gates directly to your buildings.
  2. The second zone of protection is from 5 feet to 30 feet away from your buildings. In this area you should limit your plantings to fire resistant plants in separated groupings, spaced apart to avoid fire spreading through unbroken lines of plants. OSU Extension especially recommends a broad sweep of well watered and mowed lawn as a fire break.
  3. The third zone is 30’ or further from your house. This area is where flammable materials and less fire resistant plants should be located.

Practice Firewise landscape maintenance

  1. Protect your roof! Remove pine needles or other plant debris from gutters, roofs and roof vents.
  2. Trim tree branches that overhang your roof. Create a minimum of 15 feet of clearance from the roof to any trees.
  3. Ivy growing on trees holds lots of dead, dry leaves against the tree trunks. Kill ivy growing up your trees by cutting a 3’ air-gap where ivy isn’t allowed to grow. First cut the ivy at chest height, then cut the ivy again 3’ below your first cuts. Remove the ivy from the gap area. The ivy above will die and the leaves and old dry debris will gradually fall to the ground. Watch this air-gapping demo YouTube video by Alexis from the Tryon Creek Watershed Council. For extra tree protection, pull the remaining ivy away from the tree trunk leaving a clearance of 7 feet from the tree.
  4. Use the right mulch. Do not use bark mulch within 5’ of your home. Avoid recycled rubber mulch materials, which are highly flammable. Instead, consider using nonflammable decorative rock and gravel in areas adjacent to your home.
  5. Store flammable materials, like lawnmower gas cans, propane tanks, firewood or lumber piles, 30 feet away from your buildings. It is also recommended that RV’s or boats which are large combustibles be stored as far from your home a possible, 30’ is ideal. 

For more maintenance info visit OSU Extension’s Firewise Landscaping Basics.

Plants to Avoid for a Firewise landscape: tall ornamental grasses, conifers and vines.

Avoid planting resinous trees and flammable shrubs and plants within 30’ of your house or other structures. Highly flammable plants typically have a lot of dead, dry inner material, aromatic leaves, waxy/oily leaves, twigs or stems, sap with a strong odor and/or papery/loose bark.

Ornamental grasses, conifers and vines add design and beauty to a landscape. Unfortunately, these plants have characteristics not suited for a firewise design close to buildings.

Conifers contain flammable oils or resins. Most conifers also have a dense form that tends to hold dead needles in their interior. If your conifer is retaining these old needles, brush or shake them out of the accessible areas of the tree or shrub.

Do not plant conifers close to your house. Place them 30’ away from your home in isolated planting areas. Space other plants and shrubs farther away from conifers. If you plant under confers, limb the trees up so the plants below are separated from the conifer’s lower limbs by about 6 feet.

Continuous stands of taller grasses, including bamboo, can contribute to fire spread. Tall grasses planted beneath trees can spread fire to the branches, this is referred to as the ladder effect.

Vines can also act as a ladder fuel. If you plant vines, place them in isolated areas away from your home. Only one vine, honeysuckle, is recommended as a fire-wise plant. Avoid planting vines under other vegetation.

English Holly is not a fire-wise plant due to it’s waxy leaves. It takes a long time for English Holly leaves to decompose on the ground adding to the ground fuel load.

For more info on flammability of plant essential oils and putting out household fires, check the helpful Fire Fighter website.

Fire-wise plants

Plants that are less flammable typically have these three characteristics: the structure of the plant is open rather than dense, they don’t accumulate dead or dying material within the plant and the leaves are moist and supple. These plants include deciduous trees and shrubs, which drop all their leaves every year leaving a clean open framework of branches. Also good are perennials and annuals as they die back to the ground each year. Though, you may need to prune back old dry foliage. Broad leaf evergreen trees and shrubs are another category of fire-wise plants as their leaves are moist and supple. An exception would be plants that are grown especially for their essential oils, which are quite flammable. Examples would be peppermint, rosemary, and eucalyptus. Eucalyptus also has long lasting leaf litter creating a fuel hazard. An interesting exception is lavender, which has a less flammable essential oil.

Want to learn more? Visit OSU Extension’s Fire-resistant Plants for Home Landscapes for profiles of each of these native plants (including images).

Native plants that are good fire-wise choices

(recommendations from Amy Jo Detwiler, OSU Extension Service)

Groundcovers

  • Oregon Stonecrop/Sedum oreganum
  • Spatula-leaf Stonecrop/Sedum spathulifolium
  • Wild Strawberry/Fragaria virginiana
  • Wood Strawberry/Frageria vesca
  • Sulfur Buckwheat/Eriogonum umbellatum

Perennial plants

  • Nodding Onion/Allium cernuum
  • Yarrow/Achillea millefolium
  • Red Columbine/Aqualegia formosa
  • Sedges/Carex There are 18 native species on the Portland Plant List
  • Columbia Tickseed/Coreopsis tinctoria
  • Nutall’s Larkspur/Delphinium nuttallii
  • Pacific Bleeding Heart/Dicentra formosa
  • Smooth Alumroot/Heuchera glabra
  • Smallflowered Alumroot/Heuchera micrantha
  • Orange Honeysuckle/Lonicera ciliosa
  • Hairy Honeysuckle/Lonicera hispidula
  • Goldenrod/Solidago lepida
  • Western Meadowrue/Thalictrum occidentale

Broadleaf Evergreens

  • Kinnikinnick/Arctostaphylos uva-ursi
  • Oregon Grape/Berberis aquifolium
  • Low Oregon Grape/Berberis repens
  • Salal/Gaultheria shallon
  • Oregon Boxwood/Paxistima myrtifolia
  • Pacific Rhododendron/Rhododendron macrophyllum

Deciduous Shrubs

  • Vine Maple/Acer circinatum
  • Red OsierDogwood/ Cornus sericea
  • Oceanspray/Holodiscus discolor
  • Mock Orange/Philadelphus species
  • Pacific Ninebark/Physocarpus capitatus
  • Western Azalea/Rhododendron occidentale
  • Red Flowering Current/Ribes sanguineum
  • Woods Rose/Rosa woodsii
  • Nootka rose/Rosa nutkana
  • Bald-hip rose/Rosa gymnocarpa
  • Hooker’s Willow/Salix hookeriana
  • Scouler’s Willow/Salix scouleriana
  • Pacific Willow/Salix lucida
  • Douglas Spiraea/Spiraea douglasii
  • Blue Elderberry/Sambucus nigra
  • Red Elderberry/Sambucus racemosa
  • Snowberry/Symphoricarpos albus

Deciduous Trees

  • Bigleaf Maple/Acer macrophyllum
  • Red Alder/Alnus rubra
  • Serviceberry/Amelanchier alnifolia
  • Western redbud/Cercis occidentalis
  • Pacific Dogwood/Cornus nuttallii
  • Cascara/Frangula purshiana
  • Western Crabapple/Malus fusca
  • Quaking Aspen/Populus tremuloides
  • Chokecherry/Prunus virginiana
  • Oregon white oak/Quercus garryana