Once-a-week watering during drought stages is enough to keep turf grass alive, even in San Antonio’s primary fire season from July to September.
With ongoing drought and windy, dry conditions as of late, a few readers living near undeveloped areas are curious if their brown grass could be a fire danger. They also wondered if they should run their irrigation system on red-flag days.
So I took their concerns to a professional, Stuart Henricksen, a member of the San Antonio Fire Department’s wildfire team.
When it comes to fire-wise landscaping, the turf grass in a home landscape — whether green or brown — is considered less hazardous, provided it’s well maintained and mowed short, usually less than 4 inches, depending on the variety. That’s because grass’ moisture content, low stature and relatively low fuel load can make it function as a fire break (along with paved surfaces and bare soil). This slows down the progress of a fire across the landscape (especially compared to other woody plants, dead wood and combustible materials with higher fuel loads).
As for running irrigation systems during a wildfire, Henricksen does not recommend it. “If everyone started running (them) during a fire, it could create a loss of pressure at fire hydrants and a supply issue for fire trucks refilling their tanks to fight the fire, rendering them ineffective..”
Once-a-week watering during drought stages is enough to keep turf grass alive, if not green, even in San Antonio’s primary fire season from July to September.
Fire preparedness, Henricksen says, starts with the structure itself, by minimizing the intrusion of flying embers into areas where they can smolder and ignite combustible materials like exposed wood and 2x4s in the attic, windows, decks and underneath pier-and-beam houses.
Newer homes incorporate fire resistant construction, but even on existing homes there’s plenty you can do to reduce risk to the structure and strengthen it against embers:
- Keep shingles, roofing and skirting in good repair .
- Install 1/8-inch wire mesh screening on attic vents, eaves and boxed-in areas around and under patios and decks.
- Seal any gaps between the foundation sill plate and floor joists with metal flashing (flashing is better than spray foam).
Patios and decks merit special attention since they can be ignited by flying embers. Avoid storing firewood or anything flammable underneath. If you can’t afford to skirt the deck with screen or non-combustible materials, make sure to maintain it when you’re doing your lawn care. It’s a good place to use a rock layer underneath (instead of mulch).
The landscape itself is divided into gradually increasing zones around the house and property, depending on lot size:
- The immediate zone (0-5 feet around the house) is essentially in contact with the home’s construction materials. So it should be kept well maintained and free of flammable materials like firewood, dead or overgrown plants and flammable materials including fuel and propane. Even mulch can ignite in a wildfire, so a fire-wise landscape may use river rock instead in foundation beds around the house. Likewise, flammable or resinous plants should be avoided, especially under windows.When preparing for fire season, you don’t want leaves or debris accumulating against the house, in the gutters, or under roof eaves. And vegetation should be cleared away from contact with the roofline — that’s exactly where embers will fly during a fire.
- Moving out into a 30-foot zone around the house, a fire-wise landscape maintains a clean defensible space around the home that is “short, mowed and manicured.” The idea is to slow down an approaching fire and keep it low to the ground, denying it the ability to ladder up into trees or the home. Most of us already maintain this with a mowed lawn or groundcover interspersed with landscape beds. Keeping your grass mowed and landscape beds thoughtfully managed means it will take less water to put a fire out.
- For the extended zone (larger lots from the 30-foot mark outward), Texas A&M recommends selective thinning of brush and trees within 300 feet of the home. Avoid thickets and stacked-up piles of limbs and brush that can allow a fire to ladder up into the trees. Reducing the density of taller trees, if you live adjacent to a green belt, can help slow down an approaching fire. “It’s all about tripping the fire up as it approaches,” Henricksen says.
As for grass, it’s tall grass that could be considered more of a danger, especially underneath idling vehicles and motorized equipment (including lawn mowers). Tall grass is common in the undeveloped brushy areas around new subdivisions, where fire-wise landscapes employ mowing to create spacing and distance. (Important tip: When mowing, use a funnel when refueling to minimize the risk of spilled gas.)
Remember, grass that is low, mowed and manicured — whether green or brown — typically represents less of a fire risk. Check out online resources for more tips on preparing in advance for wildfire and assessing your home and landscape.
