Newly Seeded Lawn
Once moisture has penetrates the seer coat, germination begins and the seed begins to grow. If the seed dries out to a certain point, the areas will die and have to be re-seeded.
Water newly seeded areas very heavily at first. Completely saturate the new loam. It may take 2 or 3 hours, and sometimes more per section. Do not leave dry pockets in the new loam. Later on these dry areas will pull moisture away from the surface areas where the seed is.
After the total loam mass has been saturated, concentrate on keeping the surface moist. When temperatures are above 60 degrees fahrenheit, water once a day especially if it has been windy. Germination should take about 7 to 10 days. As grass grows you may extend periods between watering. Never remove any of the hay mulch, it will decompose and add to the soil. If the grass seeding is successful you will lose sight of the hay in about 3 weeks.
If seeding is successful, you should be ready for the first mowing by day 21 or when the grass is about 4 inches tall. Let the soil dry out somewhat before mowing, it will firm up the soil and do less damage to the new grass.
At the first mowing, always set the mower to its highest cutting height. Never use a riding mower for the first few cuttings. After the first few times, you can bring down the cutting heights one setting for each mowing until desired height is reached.