Your efforts to restore your lawn will be in vain if you do not care for the young grass plants as the seeds germinate and begin to grow. The most critical need is to apply water at least twice a day, assuming no rain. If the soil dries out, the seedlings will not germinate or will soon wither and die.
To maximize the germination rate, soak your lawn on the same day you sow the seeds. On the next day, assuming no rain, lightly sprinkle or mist the lawn for about five minutes morning and afternoon. Be sure you have moistened the soil to a depth of 1-inch. Keep the overseeded lawn moist until the young grass plants are 2-inches tall by repeating a light watering every day after periods without rain. This will take four to six weeks.
Stay off the seeded areas, except to fertilize once more. If needed, apply a second dose of a ½-pound of nitrogen per 1,000-square feet six weeks after germination. However, do not add more fertilizer if the grass will soon be dormant.
When the grass is 2-inches tall, resume normal watering patterns. Begin mowing again once the grass reaches 3- to 4-inches tall before it is long enough to fall over. Make sure your mower blade is sharp; a dull one may tear up young grass plants.