Bulloch County Extension

Don’t let watering your lawn be too much of a good thing

Turfgrasses, like all living plants, require water for growth and survival. Since rainfall patterns vary sometimes it’s necessary to supplement and irrigate your lawn.  Most all warm season perennial grass lawns (Centipede, Bermuda, St. Augustine, and  Zoysia) require about one inch of water a week.  However overwatering can result in some major problems.  Some of the problems that may result from overwatering include:  shallow root system, increased diseases, increased weeds, increased insect infestations, reduced drought tolerance, increased thatch and excessive growth, and reduced tolerance to other stresses such as shade and soil problems.  If using an automated sprinkler system, turn if off if rain is in the forecast.  Here are some tips for proper lawn watering.

Let Your Lawn Tell You When to Water

Lawns should be irrigated when approximately 50% of the lawn shows signs of wilt. These signs include:

• Leaf blades are folded in half lengthwise in an attempt to conserve water.

• The grass takes on a blue-gray tint.

• Footprints or tire tracks remain visible on the grass long after being made.

Select The Correct Sprinkler

Water should never be applied at a rate faster than it can be absorbed by the soil. If the sprinkler applies too much water, it runs off and is wasted. This seldom happens with small sprinklers unless the lawn is very dense or the soil is compacted.

How to Calibrate a Sprinkler: Knowing the amount of water an irrigation system applies over a certain time period is an important step in using water efficiently. Most people irrigate for a given number of minutes without knowing how much water they are really applying. This leads either to giving too little water or to wasted water, which runs down sidewalks and streets, or through the root zone and deep into the ground where grass roots cannot reach it. Calibrating or determining the rate of water a sprinkler system applies is an easy job. Use the following procedure for an in-ground system or a sprinkler at the end of a hose.

Step 1: Obtain several (five to 10) coffee cans, tuna cans or other straight-sided containers to catch the irrigation water. Containers that are 3 to 6 inches in diameter work best.

Step 2: If you have an in-ground system, randomly place the containers in one zone at a time. Repeat the entire procedure in every zone because the irrigation rates may differ. If you use a hose-end sprinkler to water turf, place the containers in a straight line from the sprinkler to the edge of the watering pattern. Space the containers evenly.

Step 3: Turn the water on for 15 minutes.

Step 4: After the elapsed time, collect the cans and pour the water into a single can.

Step 5: Measure the depth of water you collected .

Step 6: Calculate the average depth of water by dividing the amount of collected water in inches by the number of cans.

Step 7: Multiply the average depth by 4 to determine the application rate in inches per hour. Now that you know the sprinkler system irrigation rate, you can apply water more efficiently.

Use Table 1 as a guide for sprinkler times. For example, if the sprinkler system applies water at the rate of 2 inches per hour and you wish to apply three-quarters of an inch, then run the sprinklers for about 23 minutes. To determine how long to run a sprinkler system for irrigation rates not listed in Table 1, use Equation 1 in the box below.