Bare patches and brown spots are common lawn problems. Fortunately they are also easily repaired. The best time to seed a bare spot in your lawn is in late summer to early fall. This allows new grass to grow stronger and deeper root systems during the fall and winter. Weeds are also slower growing in the fall as compared to springtime. If the patch must be seeded in the spring it's best to start as early as possible so that new grass can get well established before the hot summer months.
Rake the bare patch of the lawn with a hard-tined garden rake. Remove weeds and as much of the dead grass as possible. Use a three-pronged garden cultivator or the rake to loosen the top few inches of soil.
Spread approximately two inches of loam or well aged compost over the patch and overlap about six inches onto the surrounding lawn. Lightly mix the loam or compost into the loosened topsoil using the rake and then level it out. Spray with water to moisten the soil.
Spread the grass seed evenly over the patch including the area that overlaps with the healthy lawn. Use a multi-purpose grass seed designed to germinate quickly. A seed mix containing varieties of fescue and perennial rye grass works well. Do your best to match the new seed variety to the color and texture of the existing lawn. Small patches can be seeded by hand but a hand-held spreader will do a better job of distributing seed evenly over larger areas.
Lightly rake the seed into the soil to work it below the surface. Compress the entire area using a lawn roller if available. If not, tamp the soil down with your feet. Wear smooth soled shoes or boots as deep treads will make the soil uneven.
Spray the patch with a fine mist to keep the soil moist. Continue watering in this way several times a day until the new grass is one to two inches high. Start mowing the patch along with the rest of the lawn when the new grass is about two inches high.