What NOT to plant for fire season

I have always loved what I call the “Tucson Gardening Style“. No broad swathes of grassy lawn browning in the sunshine. No water-guzzling attempts at English flower garden borders limp in the heat. Just native plants left where they were growing before any house was built: prickly pear cacti squeezed side-by-side with creosote bushes and saguaros and agaves and chollas and mesquites. And most of the time these Sonoran desert natives grow right up to the side of the house.

But on June 5th, after the Bighorn wildfire burst into life north of Tucson, this native plant gardening style suddenly seemed less charming and more threatening.

At first the Bighorn fire was just billowing smoke high up in the Santa Catalina Mountains. By June 9 when I drove around northern Tucson to to take photos for another blog, I began to realize an inferno would result if this fire reached down into the upscale Catalina Foothills neighborhood which had only hours before been designated as a threatened evacuation zone.

As I took a few pictures I also realized that in California, where I used to live, the “Tucson Gardening Style” would bring the fire service knocking at the door armed with chain saws and big fines. The law in California is that there must be a 100 foot cleared open space around a home and it is aggressively enforced.

There is, however, such a live-and-let-live “Nobody’s going to tell me what to do” outlook by many Arizonans that it is unlikely that type of regulation would ever be passed here.

Okay, while I live in Arizona now I’m going to ignore local attitudes regarding plants because wildfires happen here and throughout the Western United States. Here are some recommendations about garden plantings to help prevent your home turning into an pile of burnt rubble from an urban or wild fire.

First, clear plants away from the sides of your home and other buildings. Don’t let any shrubs or trees touch or almost touch a building. If the plants catch fire — even if ignited by sparks from a neighbor’s BBQ instead of a wildfire–your home could burst into flames before you even notice it.

While many trees suitable for hot dry climates have oily leaves, the Australian-native Eucalyptus trees are among the worst. Sure, they smell so good, but they are 50 foot high torches just waiting for a little spark to light them. As much as they seem to be great trees for hot dry climates (fast growth, low water usage, lovely dappled shade), they are not. As witness: the massive fires racing through the Eucalyptus forests of Australia in recent years.

I have also seen palm trees burning as 50 foot high torches in Los Angeles during an urban fire, but while embers fell from the palms, they did not seems as potentially dangerous as a flaming eucalyptus with its branches whipping in the wind casting sparks all over the area.

For very a different reason don’t plant a Cottonwood, a major water-sucking plant. Again, it is a fast grower, but will guzzle every drop of water in the ground around it and deprive other plants of water, leaving them tinder-dry. Cottonwood roots will also invade your plumbing and septic systems.

One grass is on the Do Not Plant list:

Buffelgrass (Cenchrus ciliaris L., or Pennisetum ciliare L.) is often called white fountain grass. An African native, it grows and blooms quickly, then dies back to leave dry, quick-burning fields waiting for a lightning strike to start burning. This grass, a threat to native plants including Arizona’s famous Saguaro cactus, has been mentioned as a key factor in the origin of the Bighorn fire. You can view a new webinar on the topic of buffelgrass damage to the Saguaro National Park .

Instead of Buffelgrass, consider Red fountain grass (Cordyline) which is less invasive and stays where it is planted. The much larger South American-native Pampas grass (Cortaderia selloana) will also stay where it is planted in a desert climate, but not if there is a pond or stream nearby. In that case it becomes invasive forcing out native plants.

Now onto something more positive. While the evidence is anecdotal, a few homeowners have sworn that their huge water-logged agaves saved their homes during a wildfire. I’ve seen the photos and the agaves encircling the homes look as if they have melted, but the houses were spared. It’s important to note that there was a cleared space between the house and the agaves and beyond the agaves, too.

As for planting any trees or agaves, wait until fall. It is too hot now and there is a great risk that anything you plant will die of heat at this time of year no matter how much you water it. Don’t let the landscape guy tell you otherwise!

The Bighorn fire is still burning on June 19th, but because of a wind shift, it is moving northeast, away from Tucson proper. A photo of it taken yesterday is at the top of this post. According to reports over 3,000 Saguaros have already been destroyed, but–happy news–most of the wild animals in the fire path, including baby mountain goats, have escaped. And there has been no loss of homes or human life so far.

Here is what happens to an SUV when the Forest Service makes a Phos-Chek drop. It’s that red stuff fixed wing airplanes drop on the edges of fires.

---

Our 8 most popular newsletters

1. Best and beautiful native shrubs for extreme heat
2. Five fragrant plants for your garden
3. Where to get free or cheap trees for your garden
4. Six distinctively different landscapes to replace a lawn
5. Cover up that naked wall
6. Nine trees to combat climate change
7. Four desert trees good for soil, 4 toxic ones
8. Plants that bloom even in mid-summer scorching heat

---

---