Mixed Species Native Turfgrasses Beat Single Specie Lawn for Lushness & Weed Resistance

Commercial and residential lawns cover about 40 million acres more American landscape than any traditional agricultural crop.

But keeping that turfgrass looking good takes more time, effort and money than it could and carries an environmental price tag.

U.S. lawn maintenance annually consumes about 800 million gallons of gasoline, US$ 5.2 billion of fossil-fuel derived fertilizers and US$ 700 million in pesticides. Up to two thirds of the drinking water consumed in municipalities goes to watering lawns.

Dr. Mark Simmons, director of the center’s Ecosystem Design Group, led the study comparing common Bermuda grass to seven native grasses that will be published online this week in the journal Ecological Engineering.

For the study, plots of non-native Bermuda grass were established from commercially available seeds alongside plots of Buffalo grass in various combinations with other native, short grass species.

In 2009, the researchers applied different mowing and other regimes to the two-year-old turf plots. To test whether a mixture of grasses provides a good lawn, Simmons and colleagues Michelle Bertelsen, Dr. Steve Windhager and Holly Zafian used funding from Walmart to establish multiple plots of grasses in an open field at the center.

The traditional turfgrass and the native grasses responded the same to mowing once or twice a month, to two watering regimens and to the equivalent of foot traffic. However, the turf of seven native grasses produced a carpet that was 30 percent thicker in early spring than the Bermuda turf. As temperatures climbed into mid-summer and all the lawns thinned, the mixed native turfgrass still stayed 20 percent thicker than Bermuda.

Although Buffalo grass also retained its lushness into summer, the mixed native turfgrass beat both single species (monoculture) turfgrasses in weed resistance. When dandelion seeds were added by hand, those plots grew half as many dandelions as the Buffalo grass or Bermuda grass plots.

“This is just the first step to showing that having multiple grass species, basically creating a stable ecosystem that is a lawn, may have advantages for some turfgrass applications,” Simmons said.

How soon American lawns benefit from the findings depends partly on whether native grasses become more commercially available. The native grass combination that will likely work best will also vary with location, Simmons noted.