Lawns May Survive Drought with Water Conservation

Some species have more drought and heat resilience, but if soils cross the permanent wilting point, all is lost (maybe).

It’s unusual to think of your lawn actually dying, versus going dormant, but as dry periods linger, and water rationing becomes reality, we might be crossing into new territory.

Photo: Kevin Cortopassi

Imagine the cognitive shock now occurring in places like Scottsdale, Arizona, where green lawns could simply become untenable, as water limitations tighten. Soils are generally classified based on their water content and water potential. Go too low and you hit something called the permanent wilting point (pwp). That’s when plants have zero access to water, and their roots die.

Soil experts are quick to point out that different plants might not experience the same PWP. Potatoes, for instance, die before grasses. And some grasses live longer than others.

What most Americans care about, of course, are lawn grasses.

I’ve written in the past that lawns are problematic from an environmental impact perspective, yet they are not likely to go away unless faced with an existential threat. Last year, a national survey found that 79% of US homebuyers consider a “spacious and manicured” lawn an important feature.

The reality is that most homeowners will hang on to their lawns to the bitter end. So where is that end point? How dry can soils go? What’s the absolute minimum watering needed to keep some sort of green carpet alive?

Drought Resistance Among Lawn Grasses, If you want to give your lawn a fighting chance against drought, choose ultra-hardy strains. Source: Turfgrass: Science and Culture By James B. Beard

Species Resilience

Let’s begin by looking at which lawn grasses have the hardiest genetics when it comes to drought.

Douglas Dedick, a veteran landscaper who also writes for yourgreenpal.com pointed out to me that just because a lawn has turned brown, or even black, the roots are not necessarily dead.

“It's a common misconception that the lawn has died,” he says. “but it may bounce back in the spring. One of the leading causes of brown lawns in the summer is cutting them too low. To avoid a brown lawn in the summertime it is important to raise your mower deck. Now if we are looking for the longest living drought tolerant grasses, it's important to keep that in mind.”

Assuming Dedick’s point about dormancy applies, and your lawn soil is simply overtaxed, not beyond repair, what kind of grasses should you start transitioning to? He recommends using the off season to overseed and prep the lawn for the next season. Here’s a top-to-bottom list of drought hardiness to consider:

Lawn Watering Strategies

Most cities have not put a moratorium on lawn watering entirely, but many have limited this activity. The goal is to water efficiently, so that any water applied to the soil goes where it’s needed.

“One of the things we’ve found is that the act of ‘syringing,’ or watering very lightly in the day time, can prevent heat related wilt,” Dedick says. “While watering in the day is typically not recommended. If water restrictions and heat are both circumstances surrounding a lawn, syringing may pull it through.”

It’s common knowledge that water sprinkler systems are less efficient than drip irrigators, but drip systems don’t work well for the square footage of lawns. More practical ways to reduce your water footprint include watering when the sun is down to reduce evaporation, or incorporating smart irrigation that uses data from the national oceanic and atmospheric administration to tell your sprinkler system when to apply water.

Image: Source: https://intermountainfruit.org/orchard-irrigation/swc

Time to Transition

As droughts deepen in much of the country, how do you know when to give up on lawn ownership? 

The key lies under your feet. As soil scientists explain it, different soils have the ability to retain and make available water. At some point (and it may be well before the soil is completely dry), the shallow roots of your lawn grasses may lose access to ANY water, at which point they will die completely, Spring rains or not.

You can do a few things to help your grass limp along, if you expect water to become available in a few weeks: Aerate the soil. Remove “thatch” from the surface. Do a rain dance.

Ultimately, however, you may need to start to think differently, and give up your dream of a lush, manicured lawn, in exchange for a porous paver patio, or a spread of ForeverLawn synthetic grass, or some other material that requires no ongoing input of H2O

You may find that without a lawn to maintain every weekend, you have more time for kayaking, or building a new workshop, or visiting friends or reading a good book.