by Deb Lebow Aal

·    Clearing your land entirely is not a good idea (other than in Zone 0, see below). Bare earth allows hot air to travel fast, capturing embers, with nothing to slow it down. There are many examples where people felt that clearing their land would protect their homes only to find that it exacerbates the problem. 

·     “Native species are generally the best plant materials for landscaping in defensible space.” (CSU Extension – Fire Resistant Landscaping). Research in California on native species vs exotic species found a distinct advantage to native plants for fire mitigation. There are however, a number of exceptions, such as conifers.

·     Conifers in general, especially juniper, are highly flammable. While all vegetation is ultimately flammable, Juniper trees are much more prone and some towns are considering banning Junipers around homes. Conifers are more flammable due to their high oil and pitch content. That’s too bad as they are important to wildlife, but there are more fire-adapted alternatives such as Ponderosa Pine with its thick bark, and non-conifers such as Gambel oak, and Serviceberry.

In truth, where and how you plant is most critical. The bottom line is to select plants based on zones, working from your home (buildings, structures, decks, etc.) out to 100 feet or your property line, whichever is closer. 

·     Zone 0 (0-5 ft from house): Create a 3-5 foot, preferably 5 foot, buffer between your house and the surrounding landscape. This area should contain nothing flammable. Keep gutters clean, clear debris, and have nothing stored under the eaves — particularly, no wood piles! No wood mulch or wood fencing adjacent to structures. There are lots of fire-safe choices: a cement apron, a flagstone walkway, pea gravel, or any kind of rock gravel.

·     Zone 1 (within 5-30 ft of house): Plant low succulents and native plants that retain moisture. Avoid high resin content and sap plants. Avoid planting in large masses. Rather, plant in small, irregular clusters or islands with gravel and boulders in between. Irrigate regularly, yes, it’s unfortunate, but a bone-dry landscape, which some of us have attempted, is not going to help in a fire situation. No wood piles or wooden fences – metal and stucco are preferable. Use gravel, decomposed granite, or stone for pathways. These will slow a fire’s progression.

·     Zone 2 (everything further than 30 ft from structures): Keep hedges 30 feet from structure. Tree canopies should be a minimum of 6-12 feet apart. Keep up on maintenance, meaning clear weeds and brush, and prune dead branches. Limb the trees up to 100’ from houses. Don’t clear vegetation – thin it and manage it. Run lots of paths and make some rock seating areas. Landscaping this way can be really pretty and can create fire breaks.

Houses burn from an accumulation of embers. So, get rid of areas where embers can accumulate and ignite. This would include wood decks, wood piles, even wooden or wicker furniture.

Beyond that, plant diversely with plants that won’t all burn in the same pattern at once and the best design is planting in islands, surrounded by gravel, rock, and boulders, or non-flammable paths. The best model I’ve seen of this is Kelly Grummons’ space in Arvada.

And why are native plants more fire-adapted than exotics? Well, it’s mostly about the moisture content of plants. Native plants maintain a much higher “live fuel moisture content” (yeah, that’s a scientific term) than traditional plants. Lower growing natives exhibit even better fire behavior. And, because the roots of native plants typically go so deep, they have a higher likelihood of growing back after a fire. 

So, hydration takes precedence over plant lists. I am not going to give an exhaustive list of natives that do best in fire. For that, there is the internet (e.g., FireWise Plant Material and USDA’s Fire Effects Information System), but a few notes: 

·     Mulch. Wood mulch obviously is flammable, but if it is kept hydrated and not too deep (under 3”), it can be a good mulch in a fire-resistant landscape. Overhead irrigation is preferred to drip as it gets all of the mulch wet. Much better of course is gravel mulch. Native plants tend to like being planted in chip gravel anyway. You’ll have to rake or blow leaves and debris out in Fall, but other than that, it’s pretty low maintenance and doesn’t need to be replenished as often as wood mulch.

·     Shrubs. We love shrubs – native shrubs are important for the ecosystem (Richard Phillips wrote about native shrubs in our July newsletter). The primary concern for shrubs in a fire-resistant landscape is that they are “ladder fuel.” In other words, they guide the fire up. So, don’t plant shrubs near windows, vents or tree crowns; keep the grass low around shrubs; and prune dead branches and sometimes, lower branches. Some good fire-adapted native shrubs are Wood’s rose and Western Snowberry.

·     Oaks. We talk about oak trees having a very high ecosystem value. They support a myriad of caterpillar and moth species. Oaks are also good fire-resistant trees. There is no such thing as a tree that doesn’t burn, ultimately, but deciduous trees like oaks and aspens, apples and plums, can be resistant. In the right place, they can protect a house. Oak leaf litter is also good to keep under an oak tree. It will keep the tree much healthier and therefore able to resist fire. Just keep it lightly irrigated.

And one more note (this is from my permaculture class): If you’re actually building a new house from scratch, or have the luxury of siting a house on a large property, fire almost always moves uphill. So, position a house down below, preferably near a pond. If only….

Again, we are not fire experts. Consult the experts when re-doing a landscape to be fire resistant. Hopefully some of these tips can get you started on making your landscape more resilient and protecting your home in the horrific event of a fire nearby.

From: Wild Ones Front Range https://frontrange.wildones.org/ Chapter September Newsletter  – LOTS of great resources on this website for native plantings to support people, pollinators, wildlife, and fire safety!

passed on by Virginia Schultz