Expert Answers: Water your lawn at the right time of day

The state of Alabama is home to warm-season grasses that include zoysiagrass, Bermudagrass and centipedegrass, and they all require the same care to make your yard look good. So, what are the best ways to keep it green? Associate Professor and Alabama Cooperative Extension Specialist Dave Han has tips for watering, mowing and fertilizing all summer long.

Han teaches students in Auburn University’s Turfgrass Management major in the College of Agriculture. He also provides support and training in turf-related areas for Extension agents across the state. He is an expert on turf management in a wide range of areas, from golf courses and athletic fields to parks, sod farms and professional lawn care, and he serves as the educational advisor to the Alabama Turfgrass Association.

How often should I water my lawn? And for how much time?
It really depends on the species of grass, how well your soil drains and how much water your irrigation system can put out. Every system is different, so unless you know how many inches per hour your system puts out, a good rule of thumb might be twice a week for 15 to 20 minutes. You can determine your irrigation system’s output by setting out many rain gauges or other receptacles and measuring how much water they catch when you run the system for a given time. 
   

What time of day is best to water?
Early mornings are most efficient. You lose less water to evaporation by watering in the coolest time of the day before the sun comes up. But be careful about setting a timer for before you get up in the morning; if it rains overnight and the irrigation comes on when it’s not needed, you’ll waste a lot of money, and maybe even add to flooding or runoff problems.

How can I keep my lawn looking good when we go a few weeks without rain?
Southern grasses can survive long droughts by going dormant, so if you don’t mind a brown lawn, it is okay to let them go dormant. Bermudagrass, zoysiagrass, centipedegrass and St. Augustinegrass can all survive up to 90 days without any rain or irrigation while they are dormant, as long as they are healthy going into the drought. But if we have dry spells, watering once a week should keep the grass green, if not growing very fast.

Also, don’t use herbicides during droughts or when the grass is stressed by other environmental factors.

How tall and how often should I be mowing?

Most warm-season lawns do well at 1½ to 2 inches. St. Augustinegrass can be cut a little higher, at 3 to 4 inches, and tall fescue should also be cut around 3 inches tall. You should mow at least once per week, but for faster-growing grasses like bermudagrass, twice a week would be better. 

Should warm-season grasses be fertilized in the summer?
Yes. They grow fastest when it’s hot, so that’s when they need it the most. The amount of fertilizer, especially nitrogen, depends on the species of grass. For Bermudagrass, fertilize once a month between now and September with one pound of actual nitrogen per thousand square feet of grass. St Augustinegrass can be fertilized four times a season, or every six weeks. For zoysia, I would fertilize once or twice a year, and for centipede, once is sufficient.