July 22, 2008

To Water or Not?

By Zoe Elizabeth Buck, The News & Observer, Raleigh, N.C.

Jul. 22--With restrictions on watering still stringent in many Triangle communities, keeping lawns green can be a challenge -- especially as temperatures rise.

But a lawn doesn't have to be green to be healthy, explained Dan Bowman, associate professor of crop science at N.C. State University.

Bowman tends a lawn of his own at the corner of Tryon and Lake Wheeler roads in Raleigh. His lawn, at the Lake Wheeler field laboratory, is 500 square feet divided into 40 plot areas, with four sprinkler heads in each area. His team's goal is to determine the very best way to water a lawn, especially in drought conditions.

"Just because a lawn looks like it's dead doesn't mean it is dead," said Bowman. "A lot of people think this, and it isn't true. They are just going into dormancy periods when there isn't enough water."

A lawn that seems dried to a crisp during these periods could green up in no time with a little rainfall. That's good news to those who take the laissez-faire approach to grass-growing.

"I'm not surprised," said homeowner Callie Debellis, 34, a Spanish teacher at Meredith College. She lives near the Oakwood neighborhood in downtown Raleigh. "We haven't done anything, and it always comes back in the fall."

Just because grass hibernates when it needs to doesn't mean turf is immortal, Bowman said.

"If you really don't water it for weeks or months at a time, it will die, really die," said Bowman. "But tall fescue, which is what most people have in front of their houses, is just fine when watered only once a week."

During long droughts, other varieties -- including Kentucky bluegrass, Bermuda grass and zoysia grass -- appear to do better than fescue because they have storage organs called rhizomes under the ground that help them retain water longer.

"The rhizomes are underground stems, kind of like potatoes," said Bowman. "Underground, the growing points are protected from hot weather."

This doesn't mean that the grasses with rhizomes are a better choice for local lawns, however. There are a number of factors for homeowners to consider when choosing the right turf, including whether they have kids or animals, what kind of soil type and shade they have, and the look they want.

According to Bowman, resilience during an extended drought is not the most important reason to choose a turf in the Triangle area, nor does drought-resistance necessarily mean the grass is environmentally friendly. Just because a lawn looks green during a drought doesn't mean it needs less water. Eventually it will require watering again, the same amount as any other lawn.

"In terms of water savings, the ability to survive long droughts is not a good indicator," he said.

But no matter what kind of grass they grow, homeowners shouldn't worry about their grass dying this summer.

"The restrictions right now give people more than enough watering time to keep their lawns alive," Bowman said.

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