Lawn Watering Guide

The type and slope of the soil, the fertilizer used, the amount of water needed by specific plants and grass and the efficiency of sprinklers all affect how often one needs to water.

Soil Type

Lawns on sandy soil require more frequent watering than lawns or loam or clay soils. Water can be applied less often to clay and loam soils, but it should be applied more slowly to prevent runoff.


To avoid runoff on sloping areas, place sprinklers near the top of the slope. Apply water slowly for 5-15 minutes, turn off for 15 minutes, on 5-15 minutes, etc. until the correct amount of water has been applied.


Applying fertilizer to the lawn at the proper time and in the proper amount can save time, effort and money through reduced mowing and watering. Fertilizers also can be a major source of pollution of streams and groundwater if excessive amounts are applied.

The best way to determine whether your lawn requires additional plant nutrients is to have the soil tested. A soil test report will help you understand which nutrients your soil lacks and which are present in adequate amounts. The test results will include recommendations on the amounts of plant nutrients that would benefit your lawn. Soil tests are easy and inexpensive. Forms and instructions are available through the county extension office or on the Texas A&M Soil Testing Laboratory's Web site at:

To grow properly, all plants need essential nutrients. Those that are typically needed in the greatest amounts are nitrogen, phosphorus and potassium. The best fertilizer for your lawn is one that contains the ratio of these three nutrients needed as indicated by your soil test results. All fertilizer packages must list three numbers (such as 15-5-10). These numbers-known as the fertilizer analysis-represent the percentage by weight of nitrogen, phosphorus, and potassium in the fertilizer. Most soils in this area already have enough phosphorus and potassium. If the soil test indicates your lawn does not need phosphorus and/or potassium, choose a fertilizer that provides only nitrogen.

To learn more on how to fertilize for warm season grasses, click here

Trees, Shrubs and Groundcover

Established plantings do well in the summer when watered about once a week, especially if mulch is placed around plants. Apply enough water to wet the soil to a depth of at least 12 inches. Using low output sprinkler heads, bubblers, or drip irrigation systems help prevent runoff and are efficient ways to apply water. New plantings require more frequent watering the first two years. Consider Texas native, Water-Wise varieties when purchasing new or replacement plants.

How much to water

Apply enough water to wet the soil to a depth of 4-6 inches. One to one and a half ( 1-1 1/2) inches of water is usually adequate. Use a soil probe or screwdriver to determine the depth the water actually reaches.

How to water

Use a sprinkler that emits large drops of water that remain close to the ground, not one that sprays a fine mist into the air.

Determine how much water your sprinkler applies:

Set three (3) to five (5) empty cans at different distances from the spinkler with the last can near the edge of sprinkler coverage.

Run the sprinkler for 30 minutes.

Add the inches of water in all cans and divide the total inches by the number of cans to obtain an average.

Multiply the average by two (2) to determine how many inches of water are applied in one hour.

Bermuda grass will require approximately one inch of water every fifth day in the summer. Buffalo grass needs 25% less water and St. Augustine needs about 15% more.

Remember to subtract any rainfall from the amount required to determine how much water to apply.

Information supplied by the Texas Water Development Board.