A. Whatever killed the lawn is most likely gone. I know you watered twice a day, but death of an entire lawn during the summer is nearly always due to an irrigation problem. There are diseases and insects which cause damage, but they always leave behind telltale patches of green. These patches of green, to a trained eye, are clues to the cause of dying grass.
Leave it Alone
Wait until the temperatures cool down a bit, perhaps sometime between late September and mid October, to begin planting a new lawn. In the meantime, leave the dead grass in place to shade the soil and prevent weed growth. This layer of “mulch” reduces weed problems that might pop up if you were to remove it. In the meantime, continue irrigations because there are probably plant roots in that dead lawn that need the water.
|Lawn brown spots due to irrigaiton|
Check the irrigation system and make sure it's working properly and the irrigation controller is functioning. Kill and remove any weeds in the new lawn area. If using a weedkiller, spray a week in advance so the herbicide has time to disappear before planting.
Soil PrepThe day before planting the seed, irrigate to soften the soil. Rent a core aerator to punch holes all through the lawn area and rake it to remove or break up these cores.
Reseed and Topdress
Apply 10 pounds of fescue seed blend per thousand square feet of lawn area. Don't skimp on the cost of grass seed. Good grass seed is expensive. Bad grass seed is cheap.
Fertilize or NotThis is also the time to apply a fertilizer on top of the grass seed if the compost is not a “rich” compost. If the compost has fertilizer in it (a rich compost), don’t apply any fertilizer. Cover the seed with a 1/8-inch layer of compost and water twice a day. When the grass starts coming up in about five to seven days, reduce irrigations to once a day in the morning.
Mow to Thicken the Lawn
You will see grass emerge first in areas where there is good irrigation coverage. Where the grass is growing slowly, work on improving the irrigation system for better water coverage. Mow the grass no closer than 2 inches when the grass reaches 3 inches tall. Mowing causes the lawn to become denser.