Mow around the area requiring patching so the grass is 1 1/2 to 2 inches tall. Rake the bare area to remove grass clippings and thatch buildup until the soil is visible.
Loosen the soil with a hoe or garden rake to assist with seed germination and root penetration. Smooth the area with a leaf rake.
Fill in holes or low areas with topsoil. Compact the soil by patting it with the back of a shovel to hold it in place.
Apply grass seed by sprinkling it between your fingers for small areas or using a broadcast spreader for large areas. Set the spread to drop at half-rate and make two passes in a criss-cross for an even spread.
Sprinkle the seeds with water to hold them in place on the soil. Spread clean straw mulch or lawn germination fabric over the area to prevent bird loss, prevent runoff and hold moisture around the seeds for germination.
Sprinkle the seeded area two or three times a day for 10 minutes each time during the first three weeks of growth.
Remove the mulch once the seeds germinate and grow to a height of about 1 inch. The grass needs light to spread and become lush.
Mow around the seeded area until the grass is a minimum of 3 inches tall. Avoid cutting the patched grass shorter than 2 inches to prevent stunting the new sprouts.