In the Garden:
Southwestern Deserts
August, 2006
Regional Report

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Yellow dot, or wedelia, is a versatile ground cover to use instead of turf.

Lawn in the Desert

It's 115 degrees today with no relief in sight. Summer rains have been sparse in my neighborhood. I collected a scant bit of rainfall one night in the buckets below my eaves. In such a hot, dry climate, is there justification for including water-thirsty grass in the landscape?

The topic brings out strong feelings on both sides of the issue, but this article isn't meant to stir up the turf war. (I acknowledge the corny pun, but can't bring myself to delete it.) However, I would like to point out some of the pros and cons of grass, design issues to consider, and maintenance techniques that can alleviate some of the negatives.

Let's start with the positives. Sharon Dewey, author of the chapter entitled "Growing a Healthy Lawn" in Desert Landscaping for Beginners (Arizona Master Gardener Press, 2001; $14.95), explains the benefits of turf grass. Each blade of grass acts as a mini evaporative cooler, helping to reduce the temperature around your house. According to Dewey, if the sidewalk temperature is 100 degrees, the temperature at the lawn's surface stays at about 75. Grass surfaces, as opposed to concrete hardscapes, trap rainfall, helping to reduce erosion and run-off.

Turf also traps dust and breaks down pollutants. Dewey writes that 1 square foot of grass can grow 387 miles of roots! (If you've experienced difficulty in ridding a garden of Bermuda that has strayed, you won't find this number surprising.) That extensive root system is able to break down pollutants, such as sulfur dioxide and ozone, into elements that plant roots can absorb. Grass also releases oxygen. According to research, a 50 foot by 50 foot grass plot produces sufficient oxygen for a family of four. Speaking of family, grass provides a nice spot for children and pets to play.

On the negative side, grass is thirsty! According to figures from University of Arizona researchers, a healthy lawn in the Phoenix area requires 90 inches of water annually (more on that later). Power mowers require fuel, release pollutants, and create noise pollution. Grass clippings are usually bagged and transported to landfills, which creates another set of environmental issues: plastic bags, gasoline for transport, and more space to open new landfills as the older ones reach capacity. Turf grass is a heavy nitrogen feeder. Nitrogen, in the form of nitrates, is soluble and can leach into groundwater supplies or run off into water sources. Herbicides and pesticides are often part of the lawn care regimen. And turf grass doesn't provide for native creatures.

What Can You Do?
First, whether you have an existing lawn or are considering one as part of a new design, think carefully about how your family uses or benefits from it. If kids are grown and there are no pets, do you even need turf? Just because you had a lawn in some other state, doesn't mean you have to have one here! If you simply like the look of an expanse of green, there are many ground covers and low-growing perennials to do the job that require considerably less maintenance and water once established. I don't know anyone who looks forward to mowing the lawn every week in these temperatures.

If you decide you have a real use for a lawn, situate it to obtain maximum benefit. Create a safe play area in the backyard. Keep grass near the house, where it will provide a cooling effect. Eliminate those odd kidney bean shapes (often surrounded by railroad ties, go figure) that are invariably placed near the street. That design is unsafe for kids or pets, doesn't cool the home, and is difficult to mow. And yet I see them in groups throughout my community when I go for walks. It's as if the same diabolical landscaper swept through, offering everyone identical packages. If someone suggests such a thing for your new landscape, refuse it!

Proper Maintenance
Many of the negatives listed above can be reduced by proper care. As stated earlier, healthy turf in the Phoenix area uses 90 inches of water annually; however, healthy turf really needs only 54 inches of water annually. That 90 inches includes a factor called "irrigation efficiency," which takes into account water lost to wind, evaporation, runoff, and irrigating sidewalks and driveways. Desert lawn watering is only 60 percent efficient (54/.6 = 90). In other words, desert homeowners waste 40 percent of the water they apply to their lawns!

Use a push mower and let clippings lay on the grass. You'll get good exercise, and the small, moist clippings quickly decompose, returning nitrogen to the soil. You can typically reduce fertilizer applications by 25 percent with this method. In addition, you don't have to bag them for the landfill.

Unless communities decide to ban grass completely, there will always be people who have it in their landscape. If that is your choice, be a responsible friend to the desert and ensure the turf is part of a carefully thought-out design and maintenance plan.


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