By Brent McGhie, UC Master Gardener of Butte County, January 11, 2019
Fire is a normal part of the natural environment in California, so if you live in the wildland-urban interface (WUI), it's not so much a question of if, but of when your home will be exposed to wildfire. With this thought and the devastation of the Camp Fire fresh in mind, many Butte County property owners may be thinking about creating a fire-resistant landscape around their homes. Not only is this a prudent course of action, a 2005 revision of the California Public Resources Code (PRC 4291) requires that property owners create 100 feet (or to the property line) of defensible space around homes and buildings. Defensible space is defined as the area around a structure where the landscape is designed and maintained to decrease fire danger. Creating defensible space also gives firefighters an opportunity to safely protect your home.
If a fire reaches the crown of a tree, its heat intensity increases and this can increase the combustibility of surrounding vegetation. Low tree branches create fuel ladders that allow fires to climb into a tree. To prevent fires from ‘crowning,' these ladder fuels must be eliminated. Cal Fire recommends that the lower branches of a mature tree should be pruned to create a clearance of three times the height of the shrubs beneath it. For example if a shrub is four feet tall, the tree should be pruned so that there is 12 feet of clearance between the top of the shrub and the lowest branches of the tree. For younger trees, the lower one-third of branches should be removed.
The area that is 30 feet closest to a home is often called the “home defense zone” or, as Cal Fire puts it, the “Lean, Clean and Green Zone.” In this area, highly flammable fuels should be eliminated or minimized and widely spaced plants should be kept green and well irrigated. Vegetation in this zone should be comprised of shorter plants such as grasses and non-woody flowers. If shrubs or trees are planted, they should be fire-resistant plants such as deciduous trees (which shed their leaves in the fall) or non-woody natives and other perennials such as salvias. Fire-resistant ground covers are also an acceptable choice for this area. Avoid planting broadleaf evergreens (like holly and coyote bush), conifers (like pines, junipers, cedars, and firs) and palms, because they are highly flammable.
When planning a firewise landscape, the contribution of hardscape features should not be overlooked. Decomposed granite, cement, asphalt or gravel pathways and driveways make effective firebreaks. Structures such as patios and masonry walls and water features like pools, ponds, and streams will also impede the advance of a fire.
Before moving beyond the 30-foot home defense zone, mention should be made of items that do not belong too close to a home. Most propane tanks should be located a minimum of 10 feet from any structure, and woodpiles should be at least 30 feet away. A cord of seasoned firewood contains the energy equivalent of approximately 174 gallons of gasoline! Would you store that much gasoline on your porch? Also, flammable liquids such as gasoline, paint thinner and turpentine should be properly stored away from ignition sources and combustibles.
The outer 70 feet of the defensible space is called the “reduced fuel zone.” As with the home defense zone, plants in this zone should be well spaced horizontally and separated vertically to eliminate fire ladders. Fire resistant plants should also be used here. Most surface litter such as leaves, pine needles, and twigs should be removed so that this layer is no more than three inches deep. Dead annual grasses should be mowed to a height of no more than four inches. Mature trees without shrubs growing beneath them should be limbed to a height of six feet above the ground. All plants should receive adequate water and dead branches in trees and shrubs should be regularly removed. As noted in the UC Cooperative Extension's fact sheet on defensible space, “The goal of brush clearance is not to remove all vegetation. When done well, cleared areas should still include enough well-spaced and judiciously pruned plants to protect against excessive erosion and provide wildlife habitat.”
If organic mulches are used in the reduced-fuel zone, a 2008 study showed that a mulch of composted wood chips spread two to three inches deep showed the slowest fire-spread rate of the eight mulches tested. A potential disadvantage of wood chip mulches is that they tend to smolder and can be difficult to extinguish. In general, fine, stringy mulches such as shredded bark burn more rapidly than larger chunks.
Establishing defensible space can be summarized by the following three R's: 1) Remove dead and dying plant material; 2) Reduce the density of vegetation and ladder fuels; 3) Replace hazardous vegetation with less flammable, well-irrigated fire resistant plants.
Further information on fire safety for homeowners can be found in two highly recommended Cal Fire publications: “Homeowners Checklist – How to Make Your Home Fire Safe” and “Why 100 Feet?” And for property owners who are considering landscaping from scratch, the Sonoma-Marin Saving Water Partnership has developed eight fire-rebuild landscape design plans that are well worth considering.
For more information on creating fire resistant landscapes, see the Fire-Safe Landscape section of the UC Master Gardeners of Butte County website. For other topics of interest to local gardeners please visit our home page. And if you have a gardening question or problem, call the Master Gardener Hotline at (530) 538-7201.
By Laura Lukes, UC Master Gardener of Butte County, December 14, 2018
The chemistry of soil hydrophobia is fairly basic. Plant materials that burn hot release a waxy substance that penetrates the soil while still in gas form. It takes very high temperatures to produce this gas which coats soil particles when it cools and becomes solid. To the naked eye, hydrophobic soils look like their non-hydrophobic counterparts. But biologically speaking, they have now become latent disaster zones.
Runoff caused by rainfall on water-shedding soils can also cause the loss of fertile topsoil. And it can clog water conveyance facilities including manmade culverts, gutters, and ditches, as well as streams and rivers. The upside of rainfall on soil hydrophobicity is that, generally speaking, water repellency weakens with each rain event.
The type of soil and the intensity of the fire determine how deeply hydrophobia penetrates the soil, and how long the condition persists. Paradoxically, the fastest draining soils, (light, sandy soils with large pores) are the most prone to post fire hydrophobicity because they transmit the heat more easily than heavy, dense, clay soils. Soil types within the approximately 240 square miles burned by the Camp Fire vary from the sandy loam found in parts of Butte Creek Canyon to the red, rocky soils of the ridge communities. In general, the bulk of the burned area is perched atop the Tuscan formation. In its Soil Survey of Butte Area, California, Parts of Butte and Plumas Counties, the Natural Resources Conservation Service (NRCS) notes that these ridges “consist mainly of mudflow breccia, volcanic sandstone, and volcanic conglomerate.” The soils sitting on these thick layers of volcanic bedrock tend to be naturally clayey and slow draining.
Prescriptions for large scale mitigation within the burnt forested public lands, and the large acreages of undeveloped private landholdings, are outside of the scope of this article. For the private landowner, the following steps outlined by Douglas Kent in his Press Democrat article can be taken to lessen and control the damage caused by the treacherous combination of heavy rain and burn-scarred soils. These procedures can be followed if the homeowner is 1) allowed back onto his / her property and 2) able to stay long enough to put these measures in place.
To hold your ground:
- Clear drainage systems such as culverts, diversion ditches, or narrow swales, of debris. Clogged drains are a primary cause of erosion, even without fire damage.
- Divert water from areas originally designed to sheet runoff to the landscape: instead, redirect the runoff towards your newly cleared drainage systems or, if they exist, towards storm drain systems such as gutters. Use sandbags, diversion ditches, boards stacked on top of one another and staked in place, dry stacked walls, or bales to redirect water flow.
- Minimize foot and equipment traffic on burned landscapes. Such traffic can further compact already damaged soils on flat areas, and can weaken soil bonds and dislodge soil particles on slopes. Develop plans to restore your injured landscape before tramping on it, and keep all traffic to the bare minimum during restoration activities.
- Leave non-toxic debris in place wherever possible. Burnt plant remnants and other garden features can protect the landscape from wind and water erosion, and help protect any seeds and plants that survived the fire.
You may not want (or be able) to return to your property within the perimeter of the Camp Fire. On behalf of the Butte County Master Gardener Program, we hope this information will help you in the process of healing the scars on your land and those in your soul. If you don't, we hope you find peace and beauty wherever you choose to land and to landscape.
For more information on dealing with the effects of wildfire on soil, and landscaping with the possibility of fire in mind, see the Fire-Safe Landscape section of the UC Master Gardeners of Butte County website. Among other resources, see “The New Normal: Rebuilding Soil After Fire,” a PowerPoint presentation from the UC Master Gardeners of Sonoma County which covers how wildfires affect soil, soil regeneration, and strategies for dealing with toxic soil.
Photo Credits:
Camp Fire Burns on the Ridge
Source: NASA/MSFC, USGS
Area Affected by Camp Fire, Aerial View
Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community
Area Affected by Camp Fire, Relief View
Sources: National Geographic, Esri, DeLorme, HERE, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, increment P Corp.
By Alicia Springer, UC Master Gardener of Butte County, November 30, 2018
Note that our merciless summers require additional irrigation for even drought-tolerant native plants while they are getting established. A spare but regular drip-irrigation line for the first two summers will improve survival rates.
- Sedges (Carex species) and rushes (Juncus species) for sun
- Yerba buena (Clinopidium douglasii) for part-shade
Deep-rooted, larger grasses to anchor:
- Deer grass (Muhlenbergia patens)
- Native fescues (Festuca californica, F. idahoensis, F. rubrica)
- Creeping wildrye (Leymus triticoides)
Perennials that tolerate winter moist, summer dry conditions:
- Douglas iris (Iris douglasii)
- California fuchsia (Epilobium canum)
- Prostrate manzanita (Arctostaphylos uva-ursi)
- Buckwheats (Eriogonum species)
- Fleabane daisies (Erigeron species)
- Yarrow (Achillea millefolium)
- Common monkeyflower/aka sticky-monkey (Mimulus aurantiacus)
- Yellow monkeyflower/aka seep mimulus (Mimulus guttatus)
- California coneflower (Rudbeckia californica)
- Hummingbird sage (Salvia spathacea) and other salvia species
Drought-tolerant ferns for shade
- Polypody fern (Polypodium californicum)
- Western sword fern (Polystichum munitum)
- Wood fern (Dryopteris arguta)
Shrubs and small trees for banks
- Hybrid rockrose (Cistus skanbergii)
- Barberry (Berberis aka Mahonia pinnata)
- Toyon (Heteromeles arbutifolia)
- California coffeeberry (Rhamnus californica)
- Gooseberry (Ribes speciosum)
- Wood rose (Rosa gymnocarpa)
- St. Catherine's Lace (Eriogonum giganteum)
- Redbud (Cercis occidentalis)
- Mountain mahogany (Cercocarpus betuloides)
- Red twig dogwood (Cornus sericea)
- Ceanothus species
- Manzanitas (Arctostaphylos species)
For more information on gardening in our area, visit the Butte County Master Gardener web page at: http://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call our Hotline at (530) 538-720l.
By Cindy Weiner, UC Master Gardener of Butte Count, November 16, 2018
Eve Werner, landscape architect and owner of Eve's Garden Design, likes to use coffeeberry (Frangula californica) as a screen, background or hedgerow. Its blackish berries resemble coffee beans and are very attractive to birds. This evergreen shrub can grow to six to ten feet tall and wide although the cultivar ‘Eve Case' is smaller, only reaching about five feet. It is native to Butte County and grows in Upper Bidwell Park. Werner says, “This adaptable plant thrives in full sun to shade with monthly to no summer irrigation.”
Jason Mills, owner of Ecological Solutions, suggests, “If you're looking for an evergreen shrub, why not try giving the local and less commonly used hollyleaf redberry (Rhamnus ilicifolia) a shot?” Hollyleaf redberry has small serrated leaves, resembling holly. It grows best in full sun or partial shade. The flowers are small and inconspicuous but develop into beautiful red fruit, which provide food for birds. It grows five to ten feet tall and needs no summer water once established.
Mills and Whittlesey like using the large perennial bunch grass deergrass (Muhlenbergia rigens). Whittlesey says, “I use deergrass to bring a rhythm and flow into a garden. When in flower in later summer, it has a stronger architectural form which holds through the winter months. It combines readily in front of larger shrubs or as a foil for small shrubs and perennials.” Deergrass forms a dense clump to 4 feet tall and wide in full sun or light shade.
- Author: Alicia Springer, UC Master Gardener of Butte County
By Alicia Springer, UC Master Gardener of Butte County, November 2, 2018
Chicoans have a macro-example of this approach to storm water in our own Lindo Channel, which catches the overflow when Big Chico Creek runs high. While many towns direct excess storm water to concrete flood control culverts which whisk the water to treatment plants, Lindo Channel's runoff nourishes a riparian corridor of oaks, sycamores, willows, cottonwoods, and bay trees (along with nonnative brush). The stream flow recharges upper-level groundwater, and the greenery helps clear air pollution and offers sanctuary to birds and other animals large and small.
A swale is a shallow channel, bermed a bit on both sides, that lets gravity do the work of moving rainwater along a gently sloping course. The swale directs water away from structures and through a straight or meandering depression lined with river rock, grasses, or other vegetation that can tolerate periods of winter wet and summer dry (regional native plants generally fit the bill). A grassy, vegetative swale might be lined with cool-season native meadow grasses such as sedges (Carex species) or rushes (Juncus species) that thrive with winter moisture and go dormant over the dry summer. A rock-lined swale resembling a dry creek bed holds visual interest throughout the seasons. Water-loving plants can be sited closer to the flow, while more water-averse selections can keep their feet dry further up the banks.
In general, your rainwater collection surface should slope downward from the water source, or you can create a minimum 2% slope. Steep slopes can create erosion, so avoid orienting your swale down slope in such areas.
Locate your swale:
- At least five feet away from structures without a basement, or ten feet from structures with a basement.
- Away from septic systems and leach fields
- Away from a tree's crown or major root zone to avoid root rot
- In full or partial sunlight to support plantings
Anchor your artificial creek bed with larger stones, boulders, and deep-rooted plants such as deer grass (Muhenbergia rigens) and fescues (Festuca species). If space permits, larger shrubs can create a more dramatically varied look. Vegetation should be planted and at least partly established before the winter storms, so be prepared to irrigate in dry periods and through at least the first summer. Once well established, deep-rooted native plants will enjoy the cool season storm water and survive the summer heat.
From a simple gravel channel to a dry creek to a more elaborate retention pond, the hardscape elements of a rain garden project may seem daunting without step-by-step instruction. “Coastal California Rain Gardens” published by University of California Agriculture and Natural Resources (UCANR), offers detailed information about planning, building, and maintaining a rain garden. Another useful guide is “Slow it, Spread it, Sink it! Rain Gardens and Swales” published by the Napa County Resource Conservation District. Both publications offer additional plant suggestions and resource listings.
Additional information and plant names used in photos:
A dry creek rain swale in a suburban garden landscape. The swale, roughly 50 feet long x 10 feet wide, runs along a sloping driveway. Redbud (Cercis occidentalis), deergrass (Muhlenbergia rigens), St. Catherine's Lace (a buckwheat, Eriogonum giganteum), Santa Barbara daisy (Erigeron karvinskianus) and California fuchsia (Epilobium canum) are among the native species seen.
Plants that tolerate winter moisture and summer drought line the banks of the swale. Idaho fescue (Festuca idahoensis) and California fuchsia (Epilobium canum) are seen. A redwood (Sequoia sempervirens) is on a raised bank so rainwater can irrigate but not saturate the root area. The redwood will require summer watering to stay healthy in the Butte County climate unless it's near a perennial stream.
A decorative rain chain at the ‘headwaters' of the creek bed directs flow from the roof gutter. Note that the creek bed is directed away from the base of the redwood, which is on a higher bank.
Boulders and deergrass (Muhlenbergia rigens) stabilize the slope and provide pleasing visual variety. Larger native plant selections screen the property. These include toyon (Heteromeles arbutifolia), mountain mahogany (Cercocarpus betuloides), deer grass, and redbud (Cercis occidentalis).
Diagram of a grass-lined vegetative swale courtesy of Napa County Resource Conservation District.