Mulch selection makes a difference
Several years of drought have killed over a million trees in California since 2010. Most of those trees died in 2016, and more are doomed. Many local trees are not as healthy as they could be due to drought, bark beetle infestation, and disease. These trees have more dead leaves and twigs, making them susceptible to fire. Rather than allowing fire to race through your landscape, create spaces that slow or stop those flames.
California state law (PRC 4291) requires that all rural homes have a 100-foot defensible space. This space helps keep you, your family and our heroic firefighters safe. While suburban homes have different laws, fire safety is still critical and fire-safe gardening just makes good sense.
Defensible space is made up of two zones. Zone 1 is a 30-foot perimeter around any structures. Keeping Zone 1 fire safe means removing all dead vegetation from the ground, roofs and rain gutters, pruning tree branches at least 10 feet away from buildings, moving patio furniture away from trees and shrubs, and moving wood piles and other flammables into Zone 2.
Zone 2 extends 100 feet from your home. To keep Zone 2 fire safe, mow grasses to 4 inches or lower, rake up dead vegetation, and create spaces between trees and shrubs. This means removing any tree branches that are 6 feet from the ground or less, and pruning trees to be 10 to 30 feet apart, depending on the slope. Because shrubs can flame upward, they should be placed or pruned so they are three to six times their height from any trees, depending on the slope.
Mulch can add fuel to a fire, or slow its spread. The most dangerous mulches include shredded rubber or western red cedar, gorilla hair, and pine needles. Pine bark nuggets, Tahoe chips and other plant biomass from tree chipping operations create a moderate risk. Composted wood chip mulch does not create a significant fire risk.
There are no truly fire-resistant plants. Keep your home safe by planting low-growing, high-moisture plants closest to your home. When deciding where to install plants, imagine your home in the bottom of a shallow bowl. Plants should get taller, further from buildings. This helps draw fire away, rather than closer. Despite their name, evergreens are far more flammable than hardwoods.
If fire risk is especially high, remove shrubs and vines that touch your home (plant new ones later), and rake mulch at least 5 feet away from all structures.
Create a fire safety plan. Seriously. It takes 20 minutes and could save your life.
Above all else, in case of fire, get out and stay out. Everything else is temporary.
by UC Master Gardener Kate Russell
This article first appeared in the August 16, 2018 issue of the South Valley Magazine.
The most important is to create a defensible space around the house perimeter. Ideally, you should have a 30-foot “free zone” from all buildings, structures, and decks. This space gives firefighters room to their job if needed. Often firefighters will bypass a home that has little to no defensible area in which to work, opting instead for one they think they will be more likely to save.
If at your place it isn't practical to remove all vegetation, it is extremely important to remove any dead plant material — dry leaves, pine needles and highly flammable plants such as Italian cypress, pine, fir, spruce, eucalyptus, junipers, palms, Japanese honeysuckle and some ornamental grasses.
Create fire-safe zones by building concrete or stone patios, walkways, and walls. Flower beds, gardens, appropriate ground covers and mulch placed near your home can also serve as a fire-break.
Removing highly flammable plants and replacing them with fire-resistant options is highly recommended — especially if you live in a high-fire zone.
What makes a tree or shrub fire-resistant? If it's non-oily, deciduous (drops its leaves in winter), large leaved and/or has high-water content. These fare best when exposed to high heat or fire. To ensure that your plants are as fire resistant as possible, make sure they're healthy, well hydrated and free of dead wood.
Excessive vegetation adds fuel to a flame. The plants nearest your home should be widely spaced and low-growing. Avoid large masses. Instead, plant in small clusters using a wide variety of species. Here are some fire-resistant options to consider:
Trees: California live oaks, native redwoods, California bay laurel, maples, citrus, cherry, apple, strawberry tree, dogwood, ash, loquat, ‘Little Gem' magnolia, toyon, white alder, weeping bottlebrush, redbud.
Large shrubs: Aloe, ceanothus, cotoneaster, escallonia, currant, pineapple guava, flowering quince, Island bush poppy, Pacific wax myrtle, photinia, pittosporum, mock orange, plumbago, podocarpus, laurel, viburnum.
Flowering plants: Azalea, camellia, hibiscus, lavender, monkey flower, California fuchsia, coral bells, society garlic, salvia, rhododendron.
Ground covers: Woolley yarrow, Ajuga reptans, purple rockrose, creeping coprosma, creeping thyme, ice plant, mock strawberry, wild strawberry, evergreen candytuft, lantana, Lamium, African daisy, wooly thyme, star jasmine, sedum.
Vines: Trumpet vine, potato vine, Cape honeysuckle.
Mulching around your trees and shrubs will help them retain moisture, reduce weeds and provide nutrients to the soil. However, if you are in a high fire area, avoid using wood chips and or pine needles, which can feed a fire. If you do have wood-based mulch, make sure to keep it moist, and add a layer of compost on top. Using compost by itself or layers of rocks or pebbles might be a better choice.
Raging fires can produce extremely high heat. Investigators of the 2008 Trabing Fire near Watsonville reported that temperatures had reached more than 3,000 degrees. Unfortunately, no plant would survive that!
If there is a fire near you, please heed the advice from your local fire authorities and evacuate if and when you are asked to do so.
by UC Master Gardener Rebecca Jepsen
Photo: Rebecca Jepsen
This article first appeared in the August 17 issue of the San Jose Mercury News.