Evapotranspiration (ET) is a measurement of how much water a plant loses through the soil (evaporation) and through its leaves (transpiration). A warm-season turf grass in full sun, on a hot and windy day, will have a higher rate of ET (and need more water) than grass located in a shady area protected from wind. Texas Agrilife Extension maintains weather stations all over Texas and uses this weather data to calculate ET values for different regions of Texas. College Station's weather station is the TAMU Golf Course.
Getting Started With ET:
ET requirements are typically given in inches of water (including rainfall). Click here to view ET amounts and watering recommendations for College Station. But how many inches of water does your sprinkler put out in a given time period? Use this simple formula below to determine how much water your sprinkler applies in a given time period:
- Set 3 to 5 empty shallow flat-bottomed cans at different distances from the sprinkler, with the last can near the edge of sprinkler coverage.
- Run the sprinkler for 15 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 4 to determine how many inches of water the sprinkler puts out in one hour. (Or, multiply the average by 2 to determine how many inches of water the sprinkler puts out in 30 minutes.)
How Often Does Grass Need to be Watered?
It's best to water once a week, and give your grass a deep soaking every time you water. If you have soil with poor drainage you may need to water twice a week for a shorter time. To find out how often to water in the summer, locate your grass type in the table of Watering Frequency for Turf Grass below. Another easy tip is to look for footprints: if you leave footprints on the grass after walking on it, it's time to water. If the grass springs back, just relax and enjoy your beautiful turf.
Watering Frequency for Turf Grasses adapted for College Station*
||Every 2 - 5 weeks**|
||Every 7 - 10 days|
||Every 7 - 10 days|
||Every 5 days|
* Note: Adapted from Texas AgriLife Extension publications.
** Buffalograss may not need supplemental watering at all in many areas of Texas where it is adapted to grow.