Lawns don't always do as well as we had hoped they would, and they need to be sewn over. Before you start to add more grass to areas that aren't working out, improve the lawn and find out why the grass is not growing. Fix the issues and then you can proceed with sewing the seed. Replanting more grass seed will help fill in bare spots in the yard and help it look more lush.
Mow the lawn if you haven't recently. This will make the grass a bit shorter, which will help the seeds get down to the soil.
Aerate the lawn to break up the soil, get air flowing again and create places for seeds to get trapped.
Test the soil with a soil test kit to make sure that it is optimal. Grass prefers at least a 6.0 pH level. The kit will give you the exact measurements that it requires of both soil and water. These are added to a test tube along with the chemical activator that comes with the kit. You put the lid on the tube and shake. The mix will turn a color, and then you compare that color to a chart to see the pH level.
Add fertilizers to the soil to adjust the pH level if it needs it. Water the lawn afterward to soak the fertilizer in.
Rake the lawn with a fan rake to remove dirt clumps from the aeration as well as dethatch the lawn. Dethatching will loosen and remove buildup of dead grass. Removing it will help seeds grow through.
Spread seeds by hand or with a spreader. Toss or run the spreader in one direction and then rotate 90 degrees and repeat the process. The seed you choose will recommend spread quantities for overseeding lawns. This is typically less than what you would spread when sewing grass on a bare lawn. Different types of grass will have different suggested spread rates ranging anywhere from 1 pound per 1,000 square feet to 3 pounds or a little more.
Water the lawn again to help the seeds start the germination process.
Spread straw over the lawn to keep the seeds in place and keep animals away. A light covering of straw is enough since the grass that is already grown will also work to keep the seeds from washing away. If covering seeds in a bare spot, use a bit more straw since there is no grass to help out.