Fuel Maps and Fire Zones
This day and age in Northern California I think we’ve all adapted to some degree to regular fire occurrences in one place or another. You likely know a person or two at a first or second degree connection that has lost their home to wildfire. As a Landscape Designer that has learned from Landscape Architects, Architects, and Contractors I’ve worked with a few homeowners that had this experience of needing to rebuild their home.
When we talk about the landscape now, fire smart planting and landscape decisions tend to be a hot topic of conversation. I pursued my education in Horticulture Environmental Landscape Design following the 2017 fires in Sonoma County, so as I went through the Santa Rosa Junior College curriculum our instructors had made it a point to highlight the importance of plant spacing and adding in hardscape materials between plantings. As I took on work experience in Landscape Architecture Firms I learned more about vegetation maps and fire fuel zones. Also, having the opportunity to help with developing consulting documentation for Fire Smart HOA practices allowed me to learn more about coding and materials that are available out there to help create more of a fire smart environment.
Of course, no matter how much you prepare your space, in the event of a fire there’s no such thing as fireproof. The policies that are put into place are to help keep people as safe as possible in these events. Here, I would love to share what I’ve learned about fire zones, fire smart landscaping practices, and some additional thoughts on setting up and maintaining the landscape. I’d also love to provide a link to some plant options for the different landscape zones specific to the Lake County Environment, or zone 7 in Sunset Western Garden Book.
The Fire Zones
There are many resources and images on defense zones for fire safe planting out there. But being that I love playing with graphics and landscape practices can get pretty specific with designs I wanted to throw together a quick hypothetical concept plan focusing mostly on planting for a single family residence. In this scenario, assume a flat landscape on a pretty standard lot size of maybe 70’x100’. Since a standard ¼ acre lot doesn’t typically go very far into zone two, everything beyond the 30’ dotted line in the image would be considered zone 2 for fire safety.
As you read through the zone descriptions feel free to refer back to image for more guidance and information.
Zone 0 – Fire Free Zone
More recently this zone has been encouraged to be a fully hardscaped space from 0-5 feet set off of your building envelope. For materials you might think about decomposed granite, cobble or gravel, concrete, pavers, or stone. For this space homeowners are generally being discouraged from having any vegetation or planting so that there’s space for a defense crew to be able to get to and around your house if need be and there’s no vegetation sitting directly against any part of your home.
Zone 1 - Structural Protection Zone
The structural protection zone starts from the end of the fire free zone and extends out 30 feet. In this zone you want to make sure that the plants planted here are well irrigated, there’s no buildup of dead debris under shrubbery, and plants are spaced apart with another fire resistant material between them either in groups (for small perennials) or individual plantings (for larger shrubs). Any possible ladder fuels should be addressed. If there are trees in this area is their canopy away from the roofline or building and do they have clearance of at least 10 feet under their canopy. If there’s a slope in this area the spacing between plantings will want to be even more significant.
Zone 2 – Defensible Space Zone
The defensible space zone reaches from the edge of the structural protection zone out an additional 100 feet or to the edge of your property line, whichever is closer. This area starts to act as a combination of conservation and fire safety. You still want to pay attention to the plantings that are in the defensible space zone, keeping them low growing, and keeping any grass material mowed down. As an advocate for functional landscapes as well I will say that adding in some of the larger producing shrubs and trees would do well in this zone. Potentially in zone 1 as well so long as you're mindful of spacing between plants. Fruiting trees and shrubs tend to need greater irrigation and have higher water content making them less susceptible to fire than some of the trees with less irrigation and volatile oils. Any trees in the area should be limbed up so they are 10 feet off the ground and if they are smaller trees, the bottom limbs should be kept 1/3 of the way up the tree.
Zone 3 – Wildland Fuel Reduction Zone
Generally, for single family homes in a residential area you’re probably not going to need to worry about this zone. If you’re on a standard ¼ acre lot, then you’re going to be looking at practiced up to zone 2. This zone starts at the edge of the Defensible Space Zone and extends 100-200 feet or more. If you have acreage with a single-family dwelling on it you’re probably going to want to look at Zone 3 as well. This wildland fuel reduction zone is where you would be coupling conservation efforts along with fuel reduction on the land. Chances are a good portion of this area is going to be mostly left alone to do it’s thing with some seasonal intervention used to check on the health of the land over time. This would probably be a good place to connect with a local arborist, a forest specialist, or some professional horticulturist who can walk the land, take an inventory of the plants, and inform you about water movement and game trails through your landscape.
Since fire travels uphill quickly I’ve seen this zone extended further than that 200+ foot mark to account for heavy sloping on the property. If there’s a significant slope to the property grading and drainage becomes a whole other conversation at every zone.
Material and Plant Selections.
I love that all this fire zone information is so readily available to those who may be searching for it. Between the different fire safe councils, the fire protection districts, the codes and ordinances it’s simple to get access to the information that you need. A few things that I have noticed that tend to be missed in these areas of guidance are actual material recommendations. One thing that a friend and colleague educated me on was succulents. It was a plant material that, for some time, seemed to be okay in that 0-5 zone (I would have the tendency to keep them out of the zone 0 now days, if you're working with your insurance company on compliance definitely leave them out).
Plant Selection
Because the leaves of the succulents held so much water, they tended to melt rather than burst into flames. Cistus was a plant that was mentioned as a great low maintenance fire smart option, the one caveat, you had to keep the dead brush from building up underneath it and you had to keep it well irrigated. Love lavender? it's an herbaceous perennial, but only for so long, to stay fire smart with it plan to change it out before it starts to turn woody and have build up underneath. I’ve also had conversations about rosemary and tea trees and their highly combustible oils with clients in addition to oleanders which are very fast growing but also very toxic if they do happen to catch fire.
I’ve also heard about the downfall of mulch many times. Coming from a world of sustainable landscaping, I have my own bias here. Having rock and cobble areas between plants or groups of plants is a great practice, if there’s regular irrigation to plants it’s helpful to have mulch around them to assist with holding moisture in the ground. Having mulching under plants also gives a space for fallen leaf debris and fruit to decompose over time if treated and maintained properly. Most of my designs will use a mix of materials for this reason, not strictly cobble and not strictly mulch. To keep the mulch and the cobble separated from one another a border can be put in installation.
To see a combination of Material selections and more fire safe plants for your landscape and specific zones take a look at the interactive palette here:
Hardscapes
To help provide some information in material selection for zone 0 here are some very basic graphics, if you'd like more information you can take a look at the material list under zone 0 in the linked palette.
Gravel is one of the more cost effective options for hardscapes borders. There's flexibility around size, color, and type. Keep in mind that if this is for a walking path, larger round cobbles can prove to be a bit of a tripping hazard.
Decomposed Granite, it's a finer material than gravel and generally comes in a gold or a grey color. The trick to this material is to make sure that you are installing it on a flat surface. Unless it's installed with a sealant (which can get expensive), if the material is installed on a slope it can erode over time.
Concrete walkways are, in my opinion, one of the less earth friendly options. That being said, I've worked with plenty of clients who preferred the material because of the flexibility and cost of the material. There's many colors and patterns available now days for anyone interested in going the stamped concrete route.
Pavers are another flexible option for materials. It's not uncommon for them to be made out of concrete and they come in a wide variety of patterns and colors. They can also be installed with larger gaps to allow for water to run through and make its way to the soil underneath, past the sand and base rock of course. I always like to have catalogues available for clients to see all the different options. The pattern above, though small, is herringbone, which tends to be a less forgiving application. These typically may be a more expensive option from what I've seen.
The benefit of brick is that it can be a pretty simple option to source. The downside, like pavers, it's labor intensive to install well. This is a good option for anyone looking for a rustic looking zone 0 but keep in mind your budget if you're looking to have it installed by professionals. For the more expensive options, you may want to mix and match major and minor path systems with different materials.
In the upcoming weeks the hope is to also be able to get some images from out local material providers and get their information up on the site so there’s a reference point for visitors. In the meantime I’ve also put together recommendations on plants with different fire safety ratings for zones 1 and 2. When putting these lists together the considerations were water holding tendencies, whether or not the leaves contain combustible oils, native and beneficial plants, and mature height. Some of these recommendations can also be found on websites of towns and cities that have implemented their own fire safe practices.
If you have any questions, feedback, or if you’re a local supplier or contractor that would like to add something please reach out and let me know. If you want to know more about my services feel free to reach out to me HERE.
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