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Fact Sheet No. 6.305 Natural Resources SeriesIForestry by F.C. Dennis* 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. 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. 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. *Staff Forester (retired), Colorado State Forest Service 1/2012 FireWise Plant Materials • 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. 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). © Colorado State University Extension. 4/02. Revised 1/12. www.ext.colostate.edu ---PAGE BREAK--- 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 = low M = medium H = high Sun/Shade: S = sun PS = part sun Sh = shade Elevation: Y = Yes N = No ? = Questionable or unknown Approx. Approx. Elevation Approx. Water Sun/Shade Mature (1,000 ft.) Bloom Scientific Name Common Name Needs Preference Height 5 6 7 8 9 Month Flowers and Ground Covers Achillea lanulosa a Native yarrow L-H S/PS 1.5 - 2' Y Y Y Y Y Jul Achillea tomentosa b Woolly yarrow M-H S/PS Y Y N N N Jul Aconitum spp.c Monkshood M-H S 2' Y Y Y Y Y Jun-Jul Aconitum columbianum ac Columbian monkshood M-H S 2' Y Y Y Y Y Jun-Jul Ajuga reptans b Bugleweed H Sh < Y Y Y Y Y Jun-Jul Alchemilla sp. Lady’s mantle M-H PS/Sh 1' Y Y Y Y ? Jun-Jul Allium cernuum ac Nodding onion L-H S/PS 1' Y Y Y Y Y Jun Allium geyeri ac Geyer onion L-H S/PS 1' Y Y Y Y ? Jun Anaphalis margaritacea a 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 parvifolia ab Small-leaf pussytoes M S/PS Y Y Y Y Y Jun Antennaria rosea ab Rosy pussytoes M S/PS Y Y Y Y Y Jun Aquilegia spp. Columbine M-H S/PS 1 - 2' Y Y Y Y Y Jun-Jul Aquilegia coerulea a Colorado blue columbine M-H S/PS 1 - 2' Y Y Y Y Y Jun-Jul Aquilegia a 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 Y Y Y Y Y Apr-Jun Artemisia caucasica Caucasian sage L-M S/PS 1- 2' Y Y Y ? ? n/a Artemisia frigida ac Fringed sage L-M S 1 - 1.5' Y Y Y Y Y n/a Artemisia ludoviciana a Prairie sage L-M S 1 - 1.5' Y Y Y ? ? n/a Aster laevis a Smooth aster L-H S/PS 1 - 3' Y Y Y Y ? Aug-Sep Aster porteri a 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 gunnisonii a Mariposa lily M-H S .5 - 2' Y Y Y Y ? Jul-Aug Campanula rotundifolia a Common harebell M-H S .5 - 1' Y Y Y Y Y May-Oct Centranthus ruber Jupiter’s beard L-H S/Sh 2 - 2.5' Y Y Y Y ? May-Oct Cerastium strictum ab Mouse ear chickweed M S/PS 1' Y Y Y Y ? May-Jun Cerastium tomentosum b Snow-in-summer L-M S/PS 1' Y Y Y Y Y May-Jun Claytonia lanceolata a Spring beauty M Sh .5 - 1.5' Y Y Y ? ? Mar-Apr Convallaria majalis bc Lily-of-the-valley H Sh < 1' Y Y Y Y ? May-Jun Delosperma nubigenum b Hardy yellow iceplant M-H S Y Y Y ? ? Jun Delphinium spp.c Delphinium M-H S/PS .5 - Y Y Y Y Y Jun-Jul Dianthus spp. Pinks L-H S - 2' Y Y Y Y Y May-Aug Doronicum sp. Leopard’s bane H S/PS 2 - 3' Y Y Y Y ? Jul-Aug Echinacea purpureaa 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 flagellaris a Whiplash daisy, trailing L-M S < 1' Y Y ? ? ? Jun-Jul fleabane Eriogonum umbellatum a Sulphur flower M S/PS Y Y Y Y Y Jun-Jul Erysimum asperum a Western wallflower M S/PS Y Y Y Y ? Jun-Jul Gaillardia aristata a Blanket flower L-M S 1 - 1.5' Y Y Y Y Y Jul-Sep Galium boreale ab Northern bedstraw M-H Sh Y Y Y Y Y May-Jun Geranium spp. Hardy geraniums M Sh/PS 2' Y Y Y Y Y May-Oct Geranium caespitosum a 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 Aspen sunflower M S 1' ? ? ? Y Y ? quinquenervis a Helianthemum Rockrose M-H S < 1' Y Y Y ? ? May-Jun nummularium Helianthus pumilus a 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 aggregata a Scarlet gilia M S/PS 1 - 2' Y Y Y Y Y Jun-Aug ---PAGE BREAK--- Approx. Approx. Elevation Approx. Water Sun/Shade Mature (1,000 ft.) Bloom Scientific Name Common Name Needs Preference Height 5 6 7 8 9 Month Iris germanica Bearded iris L-M S 1 - 3' Y Y Y Y Y May-Jun Iris missouriensis ac Missouri 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 montanum a Sand lily L-M S < 1' Y Y Y ? ? May Liatris punctata a Dotted gayfeather VL-L S 1 - 2' Y Y Y Y Y Aug-Oct Linum lewisii ac Wild blue flax L-H S/PS 1 - 2' Y Y Y Y Y May-Sep Lupinus argenteus ac Silver lupine M Sh/PS 1 - 3' Y Y Y Y Y Jun-Jul Mertensia lanceolata a Narrow-leaved chiming bells M-H Sh/PS 1 - 2' Y Y Y Y Y May-Jun Mimulus guttatus a Yellow monkey-flower H Sh 1' ? Y Y Y Y ? Monarda fistulosa a Native beebalm M-H S/PS 1 - 2' Y Y Y Y Y Jul-Oct Oenothera caespitosa a White stemless evening L-M S 1 - 2' Y Y Y Y Y Jun-Aug primrose Papaver orientale Oriental poppy H S/Sh 2 - 3' Y Y Y Y Y May-Jun Penstemon caespitosus ab Mat penstemon L-M S < Y Y Y Y Y Jun Penstemon secundiflorus Sidebells L-M S 1 - 2' Y Y Y Y ? May-Jun Penstemon teucrioides a Germander penstemon L-M S Y Y Y ? ? Jun-Jul Penstemon virens ac Blue mist penstemon M S/PS Y Y Y Y Y May-Jun Phlox subulata Moss phlox M S < Y Y Y Y Y May Polemonium sp. Jacob’s ladder H S/PS 1 - 2' Y Y Y Y Y May-Aug Potentilla fissa a Leafy potentilla M-H PS 1' Y Y Y Y ? ? Potentilla verna b Spring potentilla M-H PS < Y Y Y Y Y Mar-May Pulsatilla patens a Pasque flower M S/PS 1' Y Y Y Y Y Mar-May Ratibida columnifera a Prairie coneflower L-M S 2' Y Y Y Y Y Jul-Sep Rudbeckia hirta a 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 Y Y Y Y Y May-Jun Scutellaria brittonii a 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 lanceolatum a Yellow stonecrop M S/PS Y Y Y Y Y Jul-Aug Sempervivum sp. Hens and chicks L-M S/PS Y Y Y Y Y n/a Senecio spartioides ac Broom groundsel VL-L S 2 - 3' Y Y ? ? ? Sep-Oct Solidago missouriensis a Smooth goldenrod L-M S 1 - 2' Y Y Y Y ? Jul-Aug Thalictrum fendleri a Fendler meadowrue H S/PS 2 - 3' ? ? Y Y Y Jul-Aug Thermopsis divaricarpa a Spreading golden banner M-H S/PS 2' Y Y Y Y ? May Tradescantia occidentalis a Western spiderwort M S/PS 1.5' Y Y Y Y ? Jun-Aug Thymus spp.b Thyme L-M S < Y Y Y Y Y Jun-Jul Veronica pectinata Speedwell L-M S < Y Y Y Y Y Apr-Jul Vinca minor b Periwinkle, 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 Pinemat manzanita M S/PS 1 - 2' Y Y Y N N n/a nevadensis ab Arctostaphylos patula a Greenleaf manzanita M S/PS 3 - 4' Y Y Y N N n/a Arctostaphylos uva-ursi ab Kinnikinnick, bearberry M S/Sh 1' Y Y Y Y Y n/a Betula glanulosa a 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 fendleri a Buckbrush, mountain lilac M S 2' Y Y Y ? ? Jul Cercocarpus intricatus a Little-leaf mountain VL-L S 4 - 6' Y Y Y Y ? n/a mahogany Cercocarpus montanus ac True mountain mahogany L-M S 4 - 6' Y Y Y Y ? n/a spp.a Rabbitbrush VL-L S 2 - 6' Y Y Y Y Y Jul-Aug Cornus stolonifera a 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 ---PAGE BREAK--- Fallugia paradoxa a Apache plume VL-L S 2 - 4' Y Y Y Y Y Jun-Oct Holodiscus dumosus a Ocean spray, L-M S/PS 4' Y Y Y Y Y Jun cliff/rock spirea Jamesia americana a 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 repens ab Creeping grape holly L-H S/Sh 1 - 2' Y Y Y Y Y Mar-May Philadelphus Little-leaf mockorange M S 2 - 3' Y Y Y Y ? Jun a Physocarpus Mountain ninebark M S/Sh 2 - 4v Y Y Y Y Y Jun monogynus a Potentilla fruticosa a Shrubby cinquefoil M S/PS 2 - 3' Y Y Y Y Y May-Sep Prunus besseyi a Western sand cherry L-M S 1 - 3' Y Y Y Y ? May Purshia tridentata a Antelope bitterbrush L-M S 1 - 2' Y Y Y ? ? Jun-Aug Ribes aureum a Golden currant M S/PS 2 - 3' Y Y Y Y Y Apr-May Rosa woodsii a Woods’ or native wild rose M S/PS 2 - 3' Y Y Y Y Y Jun-Jul Shepherdia canadensis d Russet buffaloberry M-H S 5 - 6' Y Y Y Y Y n/a spp. d Snowberry, coralberry M S/PS 2 - 3' Y Y Y Y Y n/a Viburnum edule a Highbush cranberry H S 6 - 8' Y Y Y Y Y May-Jun Yucca baccata a Banana or broad-leaf yucca VL-L S/PS 2 - 3' Y Y Y N N Jun Yucca filamentosa Adam’s needle M S/PS 2 - 3' Y Y Y N N Jun Yucca glauca a Spanish bayonet, small VL-L S/PS 2 - 3' Y Y Y Y ? Jun soapweed, Great Plains yucca Large Shrubs and Trees Acer ginnala Ginnala maple M-H S 6 - 10' Y Y Y Y Y n/a Acer glabrum a Rocky Mountain maple M-H S/Sh 6 - 10' Y Y Y Y Y n/a Acer grandidentatum a Wasatch maple M S/PS 10 - 20' Y Y Y Y ? n/a Alnus tenuifolia a Thinleaf alder H S/PS 6 - 8' Y Y Y Y Y Apr Amelanchier alnifolia ac Saskatoon alder-leaf M S/PS 6 - 8' Y Y Y Y Y Apr-May serviceberry Amelanchier utahensis a Utah serviceberry VL-M S 4 - 6' Y Y N N N May Betula fontinalis a River birch H S/PS 6 - 8' Y Y Y Y ? n/a Cercocarpus ledifolius a Mountain mahogany VL-L S 6 - 15' Y Y ? N N n/a Corylus cornuta a 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 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 opulifolius a Tall ninebark M S/PS 4 - 6' Y Y Y ? N May Populus tremuloides a Aspen M S 8 - 25' Y Y Y Y Y n/a Prunus americana a American wild plum M S/PS 4 - 6' Y Y Y Y N Apr Prunus cerasiferac Flowering plum M S/PS 8 - 10' Y Y Y ? N Apr Prunus ac Pin/fire/wild/red cherry M S/PS 6 - 8' Y Y Y ? N May Prunus virginiana Western chokecherry M-H S/PS 6 - 8' Y Y Y Y Y Apr-May melanocarpa ac Rubus deliciosus a Boulder raspberry, M S/Sh 4 - 6' Y Y Y Y Y Apr-May thimbleberry Salix amygdaloides a Peachleaf willow H S/PS 20 - 30' Y Y Y Y ? n/a Shepherdia argentea a Silver buffaloberry M S/PS 4 - 6' Y Y Y Y ? Apr Sorbus scopulina a 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 species of are native. Approx. Approx. Elevation Approx. Water Sun/Shade Mature (1,000 ft.) Bloom Scientific Name Common Name Needs Preference Height 5 6 7 8 9 Month ---PAGE BREAK--- 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, Colorado State University, 115 General Services Bldg., Fort Collins, CO 80523- 4061; (970) 491-6198; ccs_resourcecenter@ mail.colostate.edu. Printed copies cost they are available free on our website at www.ext.colostate.edu/pubs/pubs.html: • 6.302, Creating Wildfire-Defensible Zones • 6.303, Fire-Resistant Landscaping • 6.304, Forest Home Fire Safety • 7.402, Protecting Trees During Construction 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, or • self-pruning. (Self-pruning trees lose lower branches naturally, leaving a greater distance between ground and canopy.) 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. FIREWISE is a multi-agency program that encourages the development of defensible space and the prevention of catastrophic wildfire. This fact sheet was produced in cooperation with the Colorado State Forest Service. 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; (970) 491-6303: • Home Fire Protection in the Wildland Urban Interface, CSFS #142-399