no. 6.305

FireWise Plant Materials

by F.C. Dennis * (1/12)

Quick Facts...

  • FireWise landscaping can be aesthetically pleasing while reducing potential wildfire fuel.
  • Plant choice, spacing and maintenance are critical.
  • Your landscape, and the plants in it, must be maintained to retain their FireWise properties.

Creating a "defensible space" around your home is one of the most important and effective steps you can take to protect you, your family and your home from catastrophic wildfire. Defensible space is the area between a structure and an oncoming wildfire where nearby vegetation has been modified to reduce a wildfire's intensity. (See fact sheet 6.302, Creating Wildfire-Defensible Zones.)

Many people resist creating defensible space around their homes because they believe these areas will be unattractive and unnatural. This is far from true. With careful planning, FireWise landscaping can be aesthetically pleasing while reducing potential wildfire fuel. It can actually enhance beauty and property values, as well as personal safety.

Fire Resistance

Many native plants are highly flammable during different seasons of the year. At such times, left unmanaged, they can accelerate the spread of a wildfire through your neighborhood, threatening homes, property and lives.

All vegetation, naturally occurring and otherwise, is potential fuel for fire. Its type, amount and arrangement has a dramatic effect on fire behavior. There are no truly "fireproof" plant species, so plant choice, spacing and maintenance are critical to defensible space landscaping. In fact, where and how you plant may be more important than what you plant. However, given alternatives, choose plant species that tend to be more resistant to wildfire.

General concepts to keep in mind when choosing and planting FireWise species are:

  • A plant's moisture content is the single most important factor governing its volatility. (However, resin content and other factors in some species render them flammable even when the plant is well-watered.) Conifers tend to be flammable due to their oil and pitch content, regardless of their water content.
  • Deciduous plants tend to be more fire resistant because their leaves have higher moisture content and their basic chemistry is less flammable. Also, when deciduous trees are dormant, there is less fuel to carry fire through their canopies.

In some cases, there is a strong correlation between drought tolerance and fire resistance. For example, a plant may shed its leaves or needles during extreme drought. Other drought-tolerant species may have smaller leaves or thick, succulent leaves. These plants offer less fuel or have a higher moisture content, both of which help reduce fire hazard.

There also appears to be a correlation between a plant's salt tolerance and natural fire resistance. Plants adapted to salty conditions, and actually growing in salty situations, may better resist burning.

Conifers

In Colorado, conifers make up much of our natural forest. Because of their high resin content, they are more susceptible to fire.

Even though conifers are flammable, you do not need to remove all of them from around your home. Wildfire hazards usually can be effectively reduced through proper thinning and pruning of existing trees and shrubs.

When choosing conifers for your defensible space, consider those with characteristics that make them better able to survive fire:

  • Thick bark,
  • Long needles
  • Self-pruning. (Self-pruning trees lose lower branches naturally, leaving a greater distance between ground and canopy.)

Plants for a FireWise Landscape

Plants that are more resistant to wildfire have one or more of the following characteristics:

  • They grow without accumulating large amounts of combustible dead branches, needles or leaves (example: aspen).
  • They have open, loose branches with a low volume of total vegetation (examples: currant and mountain mahogany).
  • They have low sap or resin content (examples: many deciduous species).
  • They have high moisture content (examples: succulents and some herbaceous species).
  • They grow slowly and need little maintenance (do not need frequent pruning).
  • They are short and grow close to the ground (examples: wildflowers and groundcovers).
  • They can resprout following fire, thus reducing relandscaping costs (example: aspen).

Additional FireWise Guidelines

Some additional tips to follow when planning a FireWise landscape include:

  • Landscape according to the recommended defensible-space zones. The plants nearest your home should be more widely spaced and smaller than those farther away.
  • Plant in small, irregular clusters and islands, not in large masses.
  • Break up the continuity of the vegetation (fuel) with decorative rock, gravel and stepping stone pathways. This will help modify fire behavior and slow its spread across your property.
  • Plant a variety of types and species. Besides being aesthetically pleasing, this will help ensure a healthier forest by reducing Insects and diseases. Healthy, vigorous, thinned forests can better resist catastrophic fires than unhealthy ones with insect and disease problems.
  • In the event of drought and water rationing, prioritize the plants you wish to save. Provide supplemental water to those nearest your home, perhaps using "gray water."
  • Mulch to conserve moisture and reduce weed growth. Mulch can be organic (wood chips or small bark pieces) or inorganic (gravel or rock). Avoid pine bark, thick layers of pine needles or other materials that can easily carry fire.

Don't Forget Maintenance

A landscape is a dynamic, constantly changing system. Plants considered "fire resistant" and that have low fuel volumes can lose these characteristics over time. Your landscape, and the plants in it, must be maintained to retain their FireWise properties.

Be aware of the growth habits of the plants on your land and of the changes that occur seasonally. Keep a watchful eye for the need to reduce fuel volumes and fuel continuity.

  • Remove annual, herbaceous plants after they have gone to seed or when the stems become overly dry.
  • Rake up and dispose of litter as it builds up over the season.
  • Mow or trim grasses to a low height within your defensible space. This is especially important as they begin to cure and dry.
  • Remove plant parts damaged by snow, wind, frost or other agents.
  • Timely pruning is critical. It not only reduces fuel volume but also maintains healthier plants with more succulent, vigorous growth.

Additional FireWise Publications

Colorado State University Extension

The following publications are available from The University Resource Center, 115 General Services Bldg., Fort Collins, CO 80523-4061; (970) 491-6198; resourcecenter@ucm.colostate.edu. Printed copies cost $1; they are available free on our website at www.urc.colostate.edu:


Colorado State Forest Service

The following publication is available from the Colorado State Forest Service, Colorado State University, Foothills 5060 Campus Delivery, Fort Collins, CO 80523-5060:

  • Home Fire Protection in the Wildland Urban Interface, CSFS #142-399

FireWise Plant List

The following list was prepared by Phil Hoefer (retired), Colorado State Forest Service. It was reviewed by Jim Knopf, a landscape architect in Boulder, and two landscape architects on Colorado's Western Slope. Bloom time is approximate (observed in Boulder at 5,600 feet).

Key: Water needs:VL = very low L = lowM = mediumH = high
Sun/Shade: S = sun PS = part sun Sh = shade
Elevation: Y = Yes N = No ? = Questionable or unknown
Scientific Name Common Name Approx.
Water
Needs
Sun/
Shade
Preference
Approx.
Mature
Height
Elevation
(1,000 ft.)
Approx.
Bloom
Month
56789
Flowers and Ground Covers
Achillea lanulosaa Native yarrow L-H S/PS 1.5 - 2' Y Y Y Y Y Jul
Achillea tomentosab Woolly yarrow M-H S/PS .5' Y Y N N N Jul
Aconitum spp.c Monkshood M-H S 2' Y Y Y Y Y Jun-Jul
Aconitum columbianumac Columbian monkshood M-H S 2' Y Y Y Y Y Jun-Jul
Ajuga reptansb Bugleweed H Sh < .5' Y Y Y Y Y Jun-Jul
Alchemilla sp. Ladys mantle M-H PS/Sh 1' Y Y Y Y ? Jun-Jul
Allium cernuumac Nodding onion L-H S/PS 1' Y Y Y Y Y Jun
Allium geyeriac Geyer onion L-H S/PS 1' Y Y Y Y ? Jun
Anaphalis margaritaceaa Pearly everlasting L-H S 1.5 - 2.5' Y Y Y Y ? Aug
Anemone blanda Windflower M-H S/PS 1' Y Y Y Y ? Apr-May
Antennaria parvifoliaab Small-leaf pussytoes M S/PS <.5' Y Y Y Y Y Jun
Antennaria roseaab Rosy pussytoes M S/PS <.5' Y Y Y Y Y Jun
Aquilegia spp. Columbine M-H S/PS 1 - 2' Y Y Y Y Y Jun-Jul
Aquilegia coeruleaa Colorado blue columbine M-H S/PS 1 - 2' Y Y Y Y Y Jun-Jul
Aquilegia chrysanthaa Yellow columbine M-H S/PS 1 - 2' Y Y Y Y Y Jun-Aug
Arabis sp.b Rockcress L-H S < 1' Y Y Y Y Y May-Jun
Armeria maritima Sea thrift L-H S/PS .5' Y Y Y Y Y Apr-Jun
Artemisia caucasica Caucasian sage L-M S/PS 1- 2' Y Y Y ? ? n/a
Artemisia frigidaac Fringed sage L-M S 1 - 1.5' Y Y Y Y Y n/a
Artemisia ludovicianaa Prairie sage L-M S 1 - 1.5' Y Y Y ? ? n/a
Aster laevisa Smooth aster L-H S/PS 1 - 3' Y Y Y Y ? Aug-Sep
Aster porteria Porter aster L-M S 1' Y Y Y ? ? Aug-Sep
Aubrieta sp.b False rockcress M S 1' Y Y Y Y Y Apr-May
Aurinia sp.b Basket of gold M S/PS 1' Y Y Y Y Y Apr-May
Calochortus gunnisoniia Mariposa lily M-H S .5 - 2' Y Y Y Y ? Jul-Aug
Campanula rotundifoliaa Common harebell M-H S .5 - 1' Y Y Y Y Y May-Oct
Centranthus ruber Jupiters beard L-H S/Sh 2 - 2.5' Y Y Y Y ? May-Oct
Cerastium strictumab Mouse ear chickweed M S/PS 1' Y Y Y Y ? May-Jun
Cerastium tomentosumb Snow-in-summer L-M S/PS 1' Y Y Y Y Y May-Jun
Claytonia lanceolataa Spring beauty M Sh .5 - 1.5' Y Y Y ? ? Mar-Apr
Convallaria majalisbc Lily-of-the-valley H Sh < 1' Y Y Y Y ? May-Jun
Delosperma nubigenumb Hardy yellow iceplant M-H S .5' Y Y Y ? ? Jun
Delphinium spp.c Delphinium M-H S/PS .5 - 3'+ Y Y Y Y Y Jun-Jul
Dianthus spp. Pinks L-H S <.5' - 2' Y Y Y Y Y May-Aug
Doronicum sp. Leopards bane H S/PS 2 - 3' Y Y Y Y ? Jul-Aug
Echinacea purpurea Purple coneflower M S 2 - 3' Y Y Y Y Y Jul-Aug
Epilobium angustifolium Fireweed H S/PS 3' N Y Y Y Y Jul-Aug
Erigeron flagellarisa Whiplash daisy, trailing fleabane L-M S < 1' Y Y ? ? ? Jun-Jul
Eriogonum umbellatuma Sulphur flower M S/PS <.5' Y Y Y Y Y Jun-Jul
Erysimum asperuma Western wallflower M S/PS 1'+ Y Y Y Y ? Jun-Jul
Gaillardia aristataa Blanket flower L-M S 1 - 1.5' Y Y Y Y Y Jul-Sep
Galium borealeab Northern bedstraw M-H Sh <1' Y Y Y Y Y May-Jun
Geranium spp. Hardy geraniums M Sh/PS 2' Y Y Y Y Y May-Oct
Geranium caespitosuma Wild geranium M Sh/PS 2' Y Y Y Y Y May-Oct
Geum triflorum Prairie smoke M-H S/PS 1.5' Y Y Y ? ? Jun
Helianthella quinquenervisa Aspen sunflower M S 1' ? ? ? Y Y ?
Helianthemum nummularium Rockrose M-H S < 1' Y Y Y ? ? May-Jun
Helianthus pumilusa Small sunflower M S 1 - 2' Y Y Y ? ? Jun-Jul
Heuchera spp. Coral bells M-H PS/Sh 1 - 2' Y Y Y Y Y Jun-Aug
Ipomopsis aggregataa Scarlet gilia M S/PS 1 - 2' Y Y Y Y Y Jun-Aug
Iris germanica Bearded iris L-M S 1 - 3' Y Y Y Y Y May-Jun
Iris missouriensisac Missouri or Native iris M-H S 1 - 2' Y Y Y Y Y May
Lamium sp.b Dead nettle M-H Sh < 1' Y Y Y Y ? May-Jun
Lavandula spp. Lavender L-M S 1 - 2' Y Y Y ? ? Jun-Nov
Leucocrinum montanuma Sand lily L-M S < 1' Y Y Y ? ? May
Liatris punctataa Dotted gayfeather VL-L S 1 - 2' Y Y Y Y Y Aug-Oct
Linum lewisiiac Wild blue flax L-H S/PS 1 - 2' Y Y Y Y Y May-Sep
Lupinus argenteusac Silver lupine M Sh/PS 1 - 3' Y Y Y Y Y Jun-Jul
Mertensia lanceolataa Narrow-leaved chiming bells M-H Sh/PS 1 - 2' Y Y Y Y Y May-Jun
Mimulus guttatusa Yellow monkey-flower H Sh 1' ? Y Y Y Y ?
Monarda fistulosaa Native beebalm M-H S/PS 1 - 2' Y Y Y Y Y Jul-Oct
Oenothera caespitosaa White stemless evening primrose L-M S 1 - 2' Y Y Y Y Y Jun-Aug
Papaver orientale Oriental poppy H S/Sh 2 - 3' Y Y Y Y Y May-Jun
Penstemon caespitosusab Mat penstemon L-M S < .5' Y Y Y Y Y Jun
Penstemon secundiflorus Sidebells L-M S 1 - 2' Y Y Y Y ? May-Jun
Penstemon teucrioidesa Germander penstemon L-M S .5' Y Y Y ? ? Jun-Jul
Penstemon virensac Blue mist penstemon M S/PS .5' Y Y Y Y Y May-Jun
Phlox subulata Moss phlox M S < .5' Y Y Y Y Y May
Polemonium sp. Jacobs ladder H S/PS 1 - 2' Y Y Y Y Y May-Aug
Potentilla fissaa Leafy potentilla M-H PS 1' Y Y Y Y ? ?
Potentilla vernab Spring potentilla M-H PS < .5' Y Y Y Y Y Mar-May
Pulsatilla patensa Pasque flower M S/PS 1' Y Y Y Y Y Mar-May
Ratibida columniferaa Prairie coneflower L-M S 2' Y Y Y Y Y Jul-Sep
Rudbeckia hirtaa Black-eyed Susan M-H S 2 - 3' Y Y Y Y Y Jul-Sep
Salvia officinalis Cooking sage L-M S/PS 2' Y Y Y Y ? Jun
Saxifraga hirsuta Saxifrage H S/PS .5'+ Y Y Y Y Y May-Jun
Scutellaria brittoniia Skullcap M S/PS .5 - 1' Y Y Y Y ? Aug-Sep
Sedum spp.b Stonecrop M S/PS 1 - 1.5' Y Y Y Y Y Jul-Aug
Sedum lanceolatuma Yellow stonecrop M S/PS .5' Y Y Y Y Y Jul-Aug
Sempervivum sp. Hens and chicks L-M S/PS .5' Y Y Y Y Y n/a
Senecio spartioidesac Broom groundsel VL-L S 2 - 3' Y Y ? ? ? Sep-Oct
Solidago missouriensisa Smooth goldenrod L-M S 1 - 2' Y Y Y Y ? Jul-Aug
Thalictrum fendleria Fendler meadowrue H S/PS 2 - 3' ? ? Y Y Y Jul-Aug
Thermopsis divaricarpaa Spreading golden banner M-H S/PS 2' Y Y Y Y ? May
Tradescantia occidentalisa Western spiderwort M S/PS 1.5' Y Y Y Y ? Jun-Aug
Thymus spp.b Thyme L-M S < .5' Y Y Y Y Y Jun-Jul
Veronica pectinata Speedwell L-M S < .5' Y Y Y Y Y Apr-Jul
Vinca minorb Periwinkle, myrtle H Sh < 1' Y Y Y Y ? Apr-Jun
Waldsteinia sp.b Barren strawberry M-H Sh/PS < 1' Y Y Y Y ? May-Jun
Shrubs
Arctostaphylos nevadensisab Pinemat manzanita M S/PS 1 - 2' Y Y Y N N n/a
Arctostaphylos patulaa Greenleaf manzanita M S/PS 3 - 4' Y Y Y N N n/a
Arctostaphylos uva-ursiab Kinnikinnick, bearberry M S/Sh 1' Y Y Y Y Y n/a
Betula glanulosaa Bog birch H S/PS 6 - 8' Y Y Y Y Y n/a
Calluna sp. Heather H S/PS 2' Y Y Y ? ? Jul-Aug
Ceanothus fendleria Buckbrush, mountain lilac M S 2' Y Y Y ? ? Jul
Cercocarpus intricatus Little-leaf mountain mahogany VL-L S 4 - 6' Y Y Y Y ? n/a
Cercocarpus montanusac True mountain mahogany L-M S 4 - 6' Y Y Y Y ? n/a
Chrysothamnus spp.a Rabbitbrush VL-L S 2 - 6' Y Y Y Y Y Jul-Aug
Cornus stoloniferaa Redtwig dogwood H S/Sh 4 - 6' Y Y Y Y Y n/a
Cotoneaster horizontalis Spreading cotoneaster M S/PS 2 - 3' Y Y Y Y ? May-Jun
Daphne burkwoodii Burkwood daphne M S/PS 2 - 3' Y Y Y ? ? Apr-Jun
Erica sp. Heath H S/PS 1' Y Y Y ? ? Jan-Mar
Euonymus alatus Burning bush euonymus M S/Sh 1 - 6' Y Y Y ? ? n/a
Fallugia paradoxaa Apache plume VL-L S 2 - 4' Y Y Y Y Y Jun-Oct
Holodiscus dumosusa Ocean spray, cliff/rock spirea L-M S/PS 4' Y Y Y Y Y Jun
Jamesia americanaa Wax flower M-H S/Sh 2 - 6' Y Y Y Y Y Jun
Lonicera tatarica Tatarian honeysuckle M S/PS 4 - 6' Y Y Y Y Y May-Jun
Mahonia aquifolium Oregon grape holly M-H S/Sh 4 - 6' Y Y Y ? ? May-Jun
Mahonia repensab Creeping grape holly L-H S/Sh 1 - 2' Y Y Y Y Y Mar-May
Philadelphus microphyllusa Little-leaf mockorange M S 2 - 3' Y Y Y Y ? Jun
Physocarpus monogynusa Mountain ninebark M S/Sh 2 - 4' Y Y Y Y Y Jun
Potentilla fruticosaa Shrubby cinquefoil M S/PS 2 - 3' Y Y Y Y Y May-Sep
Prunus besseyia Western sand cherry L-M S 1 - 3' Y Y Y Y ? May
Purshia tridentataa Antelope bitterbrush L-M S 1 - 2' Y Y Y ? ? Jun-Aug
Ribes aureuma Golden currant M S/PS 2 - 3' Y Y Y Y Y Apr-May
Rosa woodsiia Woods' or native wild rose M S/PS 2 - 3' Y Y Y Y Y Jun-Jul
Shepherdia canadensisa Russet buffaloberry M-H S 5 - 6' Y Y Y Y Y n/a
Symphoricarpos spp.d Snowberry, coralberry M S/PS 2 - 3' Y Y Y Y Y n/a
Viburnum edulea Highbush cranberry H S 6 - 8' Y Y Y Y Y May-Jun
Yucca baccataa Banana or broad-leaf yucca VL-L S/PS 2 - 3' Y Y Y N N Jun
Yucca filamentosa Adams needle M S/PS 2 - 3' Y Y Y N N Jun
Yucca glaucaa Spanish bayonet, small soapweed, Great Plains yucca VL-L S/PS 2 - 3' Y Y Y Y ? Jun
Large Shrubs and Trees
Acer ginnala Ginnala maple M-H S 6 - 10' Y Y Y Y Y n/a
Acer glabruma Rocky Mountain maple M-H S/Sh 6 - 10' Y Y Y Y Y n/a
Acer grandidentatuma Wasatch maple M S/PS 10 - 20' Y Y Y Y ? n/a
Alnus tenuifoliaa Thinleaf alder H S/PS 6 - 8' Y Y Y Y Y Apr
Amelanchier alnifoliaac Saskatoon alder-leaf serviceberry M S/PS 6 - 8' Y Y Y Y Y Apr-May
Amelanchier utahensisa Utah serviceberry VL-M S 4 - 6' Y Y N N N May
Betula fontinalisa River birch H S/PS 6 - 8' Y Y Y Y ? n/a
Cercocarpus ledifoliusa Mountain mahogany VL-L S 6 - 15' Y Y ? N N n/a
Corylus cornutaa Filbert, beaked hazelnut H S/Sh 5 - 6' Y Y Y ? ? n/a
Crataegus spp.a Hawthorn (several native) M S 6 - 8' Y Y Y Y ? May
Fraxinus pennsylvancia Green ash M-H S 20 - 25' Y Y Y Y ? n/a
Gleditsia triacanthos Honeylocust M-H S 60 - 70' Y Y N N N May
Malus sp. Crabapple M S 10 - 15' Y Y Y Y N Apr-May
Physocarpus opulifoliusa Tall ninebark M S/PS 4 - 6' Y Y Y ? N May
Populus tremuloidesa Aspen M S 8 - 25' Y Y Y Y Y n/a
Prunus americanaa American wild plum M S/PS 4 - 6' Y Y Y Y N Apr
Prunus cerasifera Flowering plum M S/PS 8 - 10' Y Y Y ? N Apr
Prunus pennsylvanicaa Pin/fire/wild/red cherry M S/PS 6 - 8' Y Y Y ? N May
Prunus virginiana melanocarpaac Western chokecherry M-H S/PS 6 - 8' Y Y Y Y Y Apr-May
Rubus deliciosusa Boulder raspberry, thimbleberry M S/Sh 4 - 6' Y Y Y Y Y Apr-May
Salix amygdaloidesa Peachleaf willow H S/PS 20 - 30' Y Y Y Y ? n/a
Shepherdia argenteaa Silver buffaloberry M S/PS 4 - 6' Y Y Y Y ? Apr
Sorbus scopulinaa Western mountain ash M-H S/Sh 6 - 8' Y Y Y Y ? May
Syringa vulgaris Common lilac M S 6 - 8' Y Y Y Y Y May

a Native species.
b Ground cover plant.
c This species, or some species in this genus, may be poisonous to livestock, pets, wildlife and/or people under some conditions. Before planting, check with Colorado State University Extension, Colorado State Forest Service, or other knowledgeable personnel.
d Several speices of symphoricarpos are native.

* Staff Forester (retired), Colorado State Forest Service. 10/99. Revised 1/12.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

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Updated Wednesday, January 08, 2014

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