People often claim that Bermuda Grass is a drought resistant grass. This is true, but it might give you the wrong impression. As a plant, Bermuda Grass is drought resistant and capable of surviving extended dry periods in a semi-dormant state. As a lawn, Bermuda Grass requires weekly rainfall or irrigation to remain dark green, thick and lush. A drought stricken Bermuda Grass lawn will turn yellow, and then tan. With consistent rain, it will green up, but will be thinner than before and prone to weed infestations. A year after a drought hits, an un-watered Bermuda Grass lawn is usually filled with weeds.
In the South, we often have significant rainfall during the summer months but is sporadic and undependable. It usually takes a little finesse to water only when your lawn needs it. In general, lawns will need 1 inch of water every 7-10 days if there has been no significant rainfall. Try to water deeply and infrequently. For example apply 1 inch of water on a single day than .25 inches per day for four days. Deep and infrequent watering will train Bermuda Grass roots to grow deep into soil where there is more moisture. Stop watering, however if the water beings to pool or run on the surface. Wait an hour or so until the water is absorbed and begin again.
If you have an automatic sprinkler system, take a moment to investigate your control box and settings. Place a rain gauge or straight-sided jar on the lawn and turn on the sprinklers. Monitor how much water is applied in a given time period. Most systems will have several different types of sprinkler heads, so you might have to test each irrigation zone. Do not be shy about increasing the pre-set cycles during droughts or turning off the entire system after a heavy rainfall. While lack of water will affect your lawn's color and growth, excess water can kill a poorly drained Bermuda Grass lawn.
It you water your lawn with a manual sprinkler, use your gauge to make sure that you done apply more, or less, than 1 inch at a time. Again, stop watering if water begins to run on the surface.
A dormant Bermuda Grass lawn will occasionally need to watered during a winter dry spell to prevent rhizomes and stolons near the soil surface from drying out.
You will need to apply only .25 - .5 inches of water at a time. If possible, water dormant lawns when temperatures are expected to drop below 20 degrees. Wet soil will freeze and keep soil temperatures close to 32 degrees, while dry soil allows damaging sub-20 degrees air to penetrate the root zone.