The Bronze Rule: Maintain defensible zones against wildfires

I've been thinking (and blogging) about the golden and silver rules for living at the wildland-urban interface. This post is about my bronze rule, which applies in areas subject to wildfires.

You need to think about fire safety if you live in an area subject to wildfires. But don’t panic and just clear out all the vegetation. Some vegetation will actually absorb and slow a fire down. See this fascinating page on Las Pilitas Nursery's web site for more on this important topic.

Also, if you live in a chaparral habitat, you’ll find a lot of really good information from The Chaparral Institute – including many pages on the topic of fire. Like - don’t remove all your chaparral natives thinking they are just tinder waiting to explode. Some non-natives used to replace natives are actually more flammable what they replaced. 


So, here are the “traditional” fire safety or defensible zones, and how I also apply these zones when thinking about restoration gardening.  I have to make a compromise between what's ideal for fire safety, and what I can manage. I am working towards an ideal state where we can defend against a smallish fire - with the help of our stalwart fire department. But - major fire with high wind? -- I'm outta here! anyway here goes:

A thirty foot radius around your home is your primary defensible zone. Irrigate it weekly or twice a month for 15 minutes or so. As far as gardening in this zone, plant any fire-safe local natives - or other pretties or food plants that are not invasive. Penstemons are Roses are nice. Dahlias are nice. Tomatoes are yummy. See – I’m not telling you to plant only local natives! This is your personal zone. But calla lilies and sweet peas — no, not where I live anyway: they escape. We all have garden favorites. Plant things that stay green with a bit of irrigation. Succulents are nice, and fire-resistant. I garden for wildlife. I use pretty local natives and other plants that are relished by butterflies, hummingbirds, and the rest of the pollinators. Also, it’s a good idea to use hardscape in this area, like rocks and gravel, and keep the area tidy - no piles of clippings you meant to move last week. I'm way behind on the irrigation front. I need to rethink that in a major way. I've just been hand watering maybe once a month.


Here's some thinning I've been doing recently, at the top of our south-facing chaparral habitat slope.

I removed this 'Dark Star' ceanothus - it was lovely, but I planted it too close to our front door and it's now about 5 feet high. Also I want to propagate our local ceanothus species and don't want them hybridizing.

Here it is gone. I also removed a lot of coyote brush and chaise from the edge of the path, opening things up. I have to do more thinning in this area. I'm enjoying revealing the manzanita - and imagining what I might plant here, thinking about perennials and annuals.

Look what I found when I cleared away some dense chaparral regrowth... a woodrat nest. Nice, but too close to the house. I'm giving them the nudge. In a few days, I'll have to knock it down. 

My new Black & Decker LPP120 20-Volt Lithium-Ion Cordless Pole Saw - a mini chain saw on a stick.  I have found it really useful so far. I got it to prune trees. Or in this case - remove shrubs. It's a bit heavy for me to hold up for long. But I'm still getting the hang of it and am happy to have this adjunct to my trusty Japanese pruning saw, for bigger jobs.

This area is next to our driveway - it's next on the list - breaks two rules: too shrubby too close to the house, and it's a nursery ceanothus that I'm afraid will hybridize with our local species. I'm going to try and grow Ceanothus papillosus, wart leaf ceanothus, farther from the house, instead of this (I think Julia Phelps?) cultivar.

A hundred foot radius is the reduced fuel zone. Thin and space out your local natives so fire can’t easily jump from one to the other (vertically as well as horizontally – no “fire ladders” into your trees). Make a few nice wide paths if you have space. Reduce the most flammable shrubs more than the least flammable. Reduce chamise more than coyote brush, as an example from a chaparral habitat. You can leave their roots, for erosion control. It means I have to prune again in a couple years, but for now I'm OK with that. Prune out dead wood and remove it (burn in winter; chip or take to the dump in summer). Focus here is on local native - but if you want a nice accent here and there from your favorite (and well-behaved) garden plants – why not? It’s your garden. It’s good to irrigate here also, just a little, but regularly, to keep plants a bit juicy. But that is not always practicable. That's a lot of irrigation.

The south slope below our home was thinned three years ago. This year I'm going to have another go at it.

Beyond 100 feet  - Las Pilitas says to continue thinning in this area. For me – I can’t manage the work load - and I'm not sure I want to. I just leave it alone as natural habitat, and enjoy thinking about nature doing its natural thing.

Across the road (still our property) I trim back from the road edge, and leave the rest undisturbed.