Home & Garden

Water trees, shrubs in drought, but let lawn go dormant

Intense heat and less than half of normal rainfall in many areas has left many landscapes dry.

Two Cornell University experts provide advice: Water trees and shrubs, but not the lawn.

"In hot dry years like this, just let the lawn go dormant," Cornell horticulture professor Frank Rossi says.

"Think of your lawn like a hibernating bear. Many lawns will turn completely brown. But most of the lawn grasses will survive four to six weeks without significant rainfall. In most cases, they'll green up again in late summer or early fall, when the rain returns and the temperatures moderate.

"Overwatering during hot weather does far more damage to a lawn than drought. Watering — particularly frequent light watering — encourages lawn diseases and weeds. The cool-season lawn grasses commonly grown in the Northeast naturally slow down as temperatures rise and soil moisture decreases, even in normal summers."

But, don't give up on trees and shrubs that shed their leaves, according to Nina Bassuk, also a Cornell professor of horticulture.

"Water them," she says. "It's better late than never. If they're still alive, they'll grow new leaves. And after two weeks of photosynthesizing, they'll have made up for the extra effort it took them to re-leaf.

"When it's really hot and dry, many trees and shrubs will shed their leaves — and some will just dry up. Drought is very stressful and can sometimes kill them outright.

Newly planted trees and shrubs are particularly vulnerable because their root systems aren't fully developed, she says. "That might mean keeping 2- to 5-year-old plantings carefully watered during dry periods, hopefully preventing drought-caused leaf damage or loss in the first place."