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.