July 09, 2002

LINCOLN, Neb. — As summer's dry, dusty days stretch on, timely management could prevent landscapes from wilting away, University of Nebraska horticulturists said.

Homeowners should prioritize watering needs, said Don Janssen, NU Cooperative Extension horticulture educator in Lancaster County.

Janssen recommends watering plants that are most important, most expensive and those that may not be able to survive extended periods without moisture. Provide enough water to sustain the lawn because reseeding can be expensive, he said, but sacrifice annuals, which must be replaced every year. Hardy perennials will survive with minimal watering.

"You're going to have to make some judgment calls," he said.

Landscapes can be monitored for drought stress symptoms such as yellow or curled leaves, drooping stems and bluish-green grass that fails to spring back when walked upon, said Anne Streich, an NU horticulturist.

Some plants have better chances of survival than others, she said. Flowers often are the first to suffer from hot, dry conditions because of their shallow root systems. Well-established trees and shrubs are usually more tolerant.

Water is especially critical for plants established in the past three years, Streich said. Two or three times a week, new shrubs and trees need two to five gallons of water and new perennials and annuals need a gallon of water.

The best time to water is between 4 a.m. and 9 a.m. when evaporation is minimized, Janssen said. The soil around most plants should be watered to no more than 3 inches deep, but moisture requirements vary, he said.

Homeowners can measure the moisture depth with a screwdriver, which easily can be shoved into damp soil. Hitting a hard spot indicates where saturation stops, he said.

Lawns may be allowed to go dormant to minimize watering. Grasses will come out of dormancy when cooler, moister conditions favor growth, but still need some water to keep the crown hydrated, he said. Dormant bluegrass needs 1 to 1.5 inches of water every two weeks; tall fescue, 1 inch every two weeks; and buffalograss and zoysia grasses, 1 inch a month.

During normal growth, buffalograss and zoysia grass need to be watered 2 to 3 inches once a month, while bluegrass and tall fescue need 1 to 1.5 inches a week.

If homeowners are unsure about their grass type, Janssen recommended taking a plant sample to a nursery for identification. Be sure to take a whole plant, not just a grass blade, he said.

If water restrictions limit irrigation, allow grass to grow taller and raise mowing height to about 3 inches, Janssen said. In flower beds, apply 1 to 1.5 inches of grass clippings or other mulches to conserve moisture and keep soil cool.

"Don't be frustrated that plants aren't looking as good as you'd like them to," he said. "Things are going to look stressed this time of year. We need to be satisfied with that and have hope for next year."

Strategic spring planting helps manage landscapes during drought, he said.

"Because this region is prone to drought conditions, group plants together with similar water needs," Janssen said. "The worst thing you can do is put plants that need a lot of water in with plants that don't need as much water. Then you're overwatering one while you're underwatering the other."

In the future, homeowners also should consider selecting plants adapted or native to Nebraska's conditions, Streich said.

"Those plants will have a better chance for survival in Nebraska's extreme climate conditions and also will reduce watering, pruning, fertilizing and pesticide use," she said.

07/09/02-SH

Anne Streich
Agronomy and Horticulture
Extension Horticulturalist
(402) 472-1640

Donald E. Janssen
Southeast Research & Extension Center - Lancaster County
Extension Educator
(402)441-7180

Sandi Alswager Karstens
IANR News and Photography
(402) 472-3030

Department: Agronomy & Horticulture