Maintaining the Home:
Home Exterior

Watering Your Lawn

Watering is important to maintain an attractive, healthy lawn. However, in places like New Mexico, water is a limited resource. Efficient water use on home lawns makes a significant contribution to water conservation.

To water your lawn efficiently:

Soak the soil in the root zone
Water only when necessary
Check sprinklers for uniform application
Test water quality

Soak the Soil in the Root Zone

Teach watering should moisten the soil to a depth of 6-8 inches on bluegrass and 8-12 inches on other grasses. This is the grass's active root zone. The length of time and amount of water needed to moisten the root zone depend on soil type and the irrigation system.Water will penetrate sandy soils more quickly and more deeply than clay soils.

To determine the length of time required to moisten your lawn's root zone:

Run the sprinklers for 15 minutes.
Dig a small hole in the ground or use a probe to determine how deeply the soil is moistened twenty-four hours later. You will use this information to determine how long to water each time.
Calculate the number of minutes to water the lawn by dividing 120 by the depth of the moistened soil in inches. For example, if the water soaked in 4 inches, figure 120/4 = 30 minutes. It would take an hour to soak in eight inches. If it soaked in 6 inches, the lawn should be watered for 20 minutes (120/6 in. = 20 minutes).

Note: Bluegrass has a shallower root system than other grasses. Therefore, it needs to be soaked to a depth of only 6-8 inches. Using the example above, if water soaked in 6 inches, you would need to water a bluegrass lawn for only 15 minutes instead of the 20 minutes calculated for other types of grass.

Once the length of the watering period is established, use the same period each time you water, no matter what the season.

If water starts to run off the lawn before the end of the watering period, turn the water off for one hour and let the water soak in; then turn the water back on and finish watering.

How often you water will change with the seasons and soil type. First determine how much water is applied during your watering period. Set straight-sided containers, such as cans, around the lawn and turn the sprinklers on for your usual watering period. At the end of the watering period, measure the amount of water in each of the cans. If the depths vary widely, the sprinkler system needs adjustment. Adjust or replace the sprinkler heads as described below to get more uniform application, then do the can test again. Use the average amount of water in the cans to determine watering frequency.

In the hottest part of the summer, bluegrass will use 1/4-1/3 inches of water per day. Bermuda grass can be maintained on 1/5-1/6 inches although it will use more if applied. If your watering period is 30 minutes on a bluegrass lawn and you apply 1 inch each time, water once every three days in the hottest part of the summer. If you are applying more water during each watering, water less often. If you are watering your lawn more than three times per week consider soil modification, a different grass species or a change in management practices. In spring and fall, water less frequently but for the same period of time.

Avoid frequent, shallow watering. It encourages a shallow root system, which makes the lawn more susceptible to drought and grub damage. Also avoid watering too deeply. Water that percolates below the root zone is wasted. Water is a scarce and valuable commodity in the Southwest and should be used carefully.

Water Only When Necessary

When the lawn needs water it will take on a bluish or dull green color and grass blades will begin to fold or roll. Also, footprints will remain visible after the lawn is walked on.

Tree and shrub roots competing with the turf will require additional water. Once a month soak the soil very deep to encourage tree and shrub root development below the turf root zone. Leave the sprinklers on three times the normal time or use a soaker hose under the entire tree canopy.

The best time of day to water is in the early morning. Less water evaporates if lawns are watered when temperatures are cool and winds are calm. These conditions occur most frequently in early morning. Late afternoon and evening watering also reduces evaporation loss if winds are calm. However, this tends to encourage disease because the grass stays moist all night. Many of the diseases that affect grass require water droplets or high humidity to infect the plants. Midday watering is more convenient for many people and does not harm the lawn, but more water is lost to evaporation.

Check Sprinklers For Uniform Application

In most situations sprinklers are the most effective way to water lawns. Flood irrigation can also be used on level lawns where a water source is available. Sprinkler spray patterns should overlap 80-100 percent depending on the type of sprinkler system. Follow the manufacturer's directions for proper sprinkler installation. A good system must provide even water distribution to all grassed areas. The water must be applied to only the grassed areas, not to walls, sidewalks, driveways or streets. Use the can test described above to gauge uniformity. Most sprinkler heads have a spring adjustment to control the flow of water. Sprinklers that water less than a full circle can be adjusted to direct water away from walls and paved areas. If some sprinkler heads have been replaced, it may be necessary to replace all of the sprinkler heads in order to achieve uniform application.

Test Water Quality

If the irrigation water is not supplied by a municipal water system, have the water quality tested before using it for irrigation. The test will determine if the water quality is good, borderline or too poor to use. If the water quality is high in soluble salts, pH, magnesium, calcium or sodium, you may need to use more water. There is no need to apply extra water unless the water you are using is of borderline quality.

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