It is very frustrating to plant grass, nourish it, take pride in it, then see dead patches looming before you. Once grass dies, it's nearly impossible to get it to grow back, regardless of how much water and fertilizer you give it. To fix the lawn, you need to reseed the patches. Preparing the ground is an essential step to the success of grass seed.
Work a rototiller over the dead patches to a depth of 4 to 6 inches. Loosen up the soil and remove as much of the dead grass and weeds as possible.
Spread an inch of sand on the patches to improve drainage. Combine it with the soil with the rototiller.
Add an inch of compost on top of the other amendments. This will make the soil more fertile. Mix it in until the top inch of soil is thoroughly combined.
Apply a starter fertilizer containing a lot of phosphorus. Use the broadcast spreader to spread it evenly. Use the rate specified on the package.
Pour grass seed into a hand spreader. If the patch is large, opt for a mechanical spreader for ease of application. Walk over the patch, dispersing the seed evenly. Too many seeds create competition for nutrients and too few will leave gaps.
Run the back of a metal rake over the grass seed. Cover it with 1/8 to 1/4 inch of the soil mixture. Seed needs direct contact with soil to germinate
Water the seed to keep it moist. Let the water run for 5 to 10 minutes two or three times daily. Stick to this routine for the first 10 days. When the seeds germinate, cut back on watering to once a day for a 15 to 30 minute interval.