Methods for Creating a Drought Tolerant Lawn; The Underground Sprinkler System

Prepared by
Michael Bauer, Former Eagle County Extension Agent,
Patrick McCarty, Extension Agent Garfield County (970 625-3969),
and Dr. Curtis E. Swift, Tri River Area, Grand Junction (970 244-1834).

  • If you have an underground sprinkler system, there are a number of things you can do to improve the efficiency of the system and reduce the amount of water needed to maintain healthy turf:
    • Use straight-sided containers such as tuna fish or cat food cans, coffee cans, or drinking glasses to determine if the lawn is being watered sufficiently and uniformly; if problems exist, make the necessary corrections.
    • The amount of water applied by a sprinkler system is determined by the type of sprinkler heads, the spacing of those heads, the number of heads per sprinkler zone, the water pressure going through the system, the time of day, and several other factors.
    • Place several straight-sided cans or glasses in the area you want to irrigate to determine the amount of water your sprinkler systems supplies, and whether there are any problems with the system. Turn the sprinkler system on for a certain amount of time and measure the amount of water collected in the containers during that time. The amount of water collected in each container indicates whether adjustments to the system are necessary. For example, if one can contains considerably less water than the others, the sprinkler head in that area is defective or not adjusted correctly. To correct the problem, you may need to add some new heads to the system, straighten existing heads, adjust nozzles, clean filters and nozzles, or change the nozzles. After correcting problems in the sprinkler system, use a rain gauge to measure any subsequent precipitation. Then, you can adjust when and how much you will water after it rains.
    • Have an irrigation audit conducted to determine the precipitation rate and uniformity distribution of your irrigation system. Check with the Irrigation Association for a certified Landscape Irrigation Auditor or Dr. Curtis Swift for further information.
  • Know the water requirement of your lawn.
    • Each time you water the lawn, apply enough water to moisten as much of the root zone as possible. Use a soil probe or shovel to determine what the average rooting depth is in your lawn. If the roots grow down six inches deep, water so the soil is moistened to at least that depth. Watering deeper may increase rooting depth which will make the turf even more drought resistant; watering excessively wastes water.
    • Various soils need different amounts of water to wet the root zone at a six-inch depth.
      • Clay - 1 to 1.5 inches of water
      • Loam - 1.0 inches of water
      • Sand - 0.5 inches of water
  • Irrigate appropriately for the turf species in your lawn.
    • Each turf species requires a different irrigation schedule. Determine the dominant turf species in your lawn and water accordingly. A healthy, high-quality bluegrass or ryegrass lawn may need up to 2.25 inches of water per week under hot, dry, windy summer conditions. Turf-type tall fescue may perform well with less water than a bluegrass lawn, if it can develop a deep root system. Buffalograss and bluegrama lawns can remain green for weeks without watering even during the hottest summer weather.
  • Check the sprinkler heads monthly to ensure they are applying water appropriately; adjust accordingly.
    • The sprinkler system should be checked throughout the watering season for problems. Don't depend on spring maintenance to be sufficient for the season. People step on or drive over sprinklers which can push the top of the sprinkler head below the ground or force the head in a different angle. Both conditions will change the arc of the water and impact the effectiveness of the water application.
    • Sprinkler heads tend to fill with grass clippings and soil particles. Check the sprinklers for debris and clean them periodically during the season. Make sure the spray pattern is not obstructed by high plants or debris.
  • Use an irrigation timer to water at night (between midnight and 6 AM); water only when necessary
    • An electronic timer is an excellent way to apply water for the proper amount of time, and during the night when there is less evaporative loss. Watering at night also will help reduce disease. Determine the best time to water and set the timer accordingly.
    • Don't place the timer on a set schedule for the entire season, however. Rather, adjust it with the changing seasons and developing needs of your lawn. Watering too frequently in the spring can kill deeper roots, which results in more watering during mid-summer to keep it alive. Spring and fall months require less watering, while the heat of summer demands more frequent watering. Adjust the timer accordingly. Find more information on watering and the potential for disease and leaf wetness
  • Adjust sprinklers so they won't throw water into trees, shrubs, or flower beds; lawn areas need to be watered separately from trees, shrubs, and flowers.
    • Lawns may need water every three or four days during the heat of summer. Shrubs may need water only about once every few weeks. Trees may need water only once a month, while flower beds may need water once a week.
    • The roots of trees, shrubs, and flower beds may rot if you water them on the same schedule that you water your lawn. Water-logged conditions are not conducive to healthy plants. Over-watered plants with root damage need more water in the heat of summer to stay alive.
  • Sprinklers should be zoned properly so lawns can be watered separately from trees, shrubs, and flowers. Also water vegetable beds and rose gardens separately from lawn areas.
    • Place trees and shrubs in areas separate from lawns. Position woody plants on higher ground if they are in the lawn area. Trees and shrubs planted in low lawn areas will likely result in reduced growth or root damage. Contact the Colorado State University Extension office in your area for further information on planting trees and shrubs.
  • Position your sprinkler system so grass in hot areas is watered separately from turf with a northern or eastern exposure; these areas require different water schedules.
    • Lawn areas exposed to direct, hot sun require more water than those shaded by fences or buildings. Consequently, sprinkler systems should be designed so certain valves control specific zones of sprinkler heads that cover different exposures. Determine what areas of the landscape receive shade at different times of the day; design the irrigation system to take these differences into account.
  • Long sloping turf areas may require several different sprinkler zones; each line of sprinklers, controlled by a valve, is called a zone.
    • Irrigation zones should be installed along the top of the slope, rather than up and down the slope. The slope may require two or more lines of sprinklers each controlled by its own valve. Adjust sprinkler zones running along the middle and bottom of the slope so they apply progressively less water than the sprinklers at the top of the slope. Water runs downhill, so less water is required further down the slope. Reduce the amount of water in each zone accordingly. Watering for the same length of time in each zone wastes water.
    • If sprinklers are installed at the base of a slope, they may not adequately water the turf at the top of the slope. What often happens is that the top of the hill will burn while the base of the slope is wet. To correct this problem, reinstall sprinklers at the top of a slope.
    • Aerate the slope on a regular basis to ensure water applied enters the soil and will not run off. Aerating allows water to soak into the soil. Aerate as needed.
  • Place sprinklers so that water from one head strikes the neighboring head; inadequate overlap results in dry spots.
    • Too much space between sprinkler heads creates dry spots. Design irrigation zones so water from one head touches the neighboring head(s). Sprinklers are best installed in a triangular pattern with water from one head touching the neighboring two heads. Sprinkler heads that do not overlap cannot be expected to properly water the intended area.
  • Install only as many heads on an irrigation zone as the water pressure can handle; dry spots will occur if there are too many heads on a zone.
    • Irrigation heads are calibrated to apply a certain amount of water over a specific area at a set water pressure. Installing more heads than the water system will handle results in dry spots. Symptoms of low water pressure often appear as donuts of green grass around the sprinkler head with dry areas between heads.
    • Gardeners who observe dry areas typically continue to water in an attempt to moisten them. This often results in excessively wet areas interspersed among dry spots. You can correct the problem by redesigning the sprinkler system and adding more zones, although this is not an easy task to accomplish.
  • Do not install different types of sprinkler heads in the same irrigation zone.
    • Rotary, spray heads, and impact sprinkler heads put out different amounts of water. Impact sprinkler heads may put out as little as 0.5 inch of water per hour, while pop-up spray heads may apply up to two inches of water per hour. Installing different sprinkler heads in the same irrigation zone will create dry areas in some places while over-watering in others.
    • Install the same type of head with the same precipitation rate in each zone. Otherwise you will waste water.

Placed on the Internet May 5, 2002

Updated May 31, 2009