I am not concerned that my bermudagrass lawn has turned a paler shade of brown. I know that warm-season lawns, such as bermuda-, centipede-, and zoysiagrass, whose optimum growing temperature is between 80 and 95 degrees F, have the ability to escape the dry conditions by going dormant. These grasses possess buds in their crowns and rhizomes (underground stems) that may remain alive and grow when more favorable conditions return. Tall fescue is a different matter. This cool-season grass, whose favorable growing temperatures are between 60 and 75 degrees F, cannot escape. Three or more weeks of no rain in the summer can injure or kill tall fescue.
Lawn owners who choose to have a green, lush lawn in summer must water their lawns during hot, dry spells. If you choose to water your lawn with potable water, then please use this precious resource properly.
Apply the correct amount of water: one-inch of water per week, which wets most clay soils to a depth of 6 to 8 inches. (It takes 640 gallons of water to irrigate 1,000 square feet of lawn, and the average household in SC uses 120 to 150 gallons of water per person per day.) If you cannot apply this amount all at once because water runs off the lawn or puddles up, then apply one-half inch at a time. Allow the water to soak in before you continue irrigating. If you use a portable sprinkler, move it frequently to avoid runoff. Use a screwdriver to determine if you applied the right amount of water. About 2 to 4 hours after watering, insert the screwdriver into the ground; it’s easier to push the screwdriver into moist soil and much harder in dry soil.
For homeowners with an in-ground irrigation system, calibrate it so you know how much water you’re applying at each irrigation event. Here’s how:
- Place several equally-sized coffee cans or other straight-sided, flat-bottomed containers randomly throughout the area to be irrigated. For above-ground, portable, hose-end sprinklers, containers should be arranged in a straight line away from the sprinklers to the edge of the water pattern.
- Turn the irrigation on for 15 minutes.
- Turn the water off, collect the cans and pour all of the water into one of the cans used.
- Measure the depth of water you collected.
- Calculate the average depth of water by dividing the total amount of water in inches by the number of cans. For instance, if the total depth was three inches, and you used six containers, then the average depth would be 3/6, or 0.5 inches. Multiply the average depth by four to determine the application rate in inches per hour. For example, one-half inch multiplied by four equals two inches per hour. If you run the system for one hour, it will apply two inches of water; run it for half an hour, and it will apply one inch. If, while the system is running, water runs off the lawn, note the time, stop the system, and let it soak in. Then turn it on again and run it until you apply the full amount of 1 inch of water.
When you operate your in-ground system, evaluate its coverage. If you’re watering the street, sidewalk, or perhaps creating a small pond in your lawn because of excessive overlap, make adjustments to ensure head-to-head coverage and an even distribution of water.
Finally, water late at night or early in the morning when dew has already formed. Use a timer to program the system to run between 11 p.m. and 2 a.m. If possible, avoid running your automatic sprinkler system between 4 a.m. and 7 a.m. out of respect for the rest of the residents of your community who like to have adequate water pressure when showering and bathing in the morning. One more thing: add a rain sensor so your neighbors won’t be talking about you when they see you watering your lawn during a frog-choking rain.
Keep in mind that watering your lawn in the summer will keep it green, but it comes with consequences. Besides having to mow that lush new growth on a regular basis, watering may encourage weed growth, stimulate disease outbreaks, and raise your water bill.
Bob Polomski © 2016