A lush, green lawn provides a place for kids to run and play while burning off energy, but these same activities can lead to unsightly bare spots in the lawn. Additional causes of bald spots in lawns include drought, disease, insects, chemical burn and smothering as a result of leaving an object on the grass for an extended period. Preparation to provide the optimal growing conditions is the key to growing new grass quickly in bare spots. While some grass species grow faster than others, use the same species as the rest of the lawn for a uniform appearance.
Determine the cause of the bald spots in the yard. No extra treatment is required if caused by foot traffic and drought. Diseases and insect infestations must be treated and controlled before growing new grass in the area. If you spilled a chemical, such as fertilizer, gasoline or even vinegar, you must remove the affected soil from the area before planting new grass.
Loosen the soil in the bare spot to a depth of at least 6 inches, using hand digging tools such as a mattock, hoe or shovel.
Blend up to 50 percent finished compost and aged manure with the native soil to improve drainage and add nutrients to the soil. This is especially important if you have heavy, clay soil with poor drainage and few nutrients. You'll have to remove some of the native soil to make room for the amendments, but you can also amend the removed soil and put it to work elsewhere in your garden.
Blend a seed starter fertilizer with the amended soil to provide about 1 pound of actual nitrogen per 1,000 square feet, which equals roughly 1 1/2 ounces of actual nitrogen per 100 square feet. Refer to the fertilizer label and the grass seed label for specific guidelines before applying the fertilizer. The compost and manure amendments work much like fertilizer, so you can skip this step if you prefer an organic gardening approach.
Drag a bow rake across the soil to spread it evenly in preparation for seeding. If desired, spread a 1-inch layer of seeding soil over the bare spot; this is available at any garden center and is designed to boost germination success.
Mix grass seed in a bucket, using 20 to 50 percent perennial ryegrass (Lolium perenne) seed in addition to the type of grass existing in the rest of your lawn. Perennial ryegrass is a particularly fast-growing grass species that germinates and fills in quickly so you'll have grass in the bald spot while the slower-growing grass species becomes established. The amount of seed needed depends on the size of the bald spot, grass species and percentage of ryegrass seed used, so you must refer to the grass seed label for specific seeding rates. For example, a 20 percent ryegrass and 80 percent Kentucky bluegrass (Poa pratensis) mixture needs a total of 2 to 2 1/2 pounds of seed per 1,000 square feet. Use 3 to 3 1/2 pounds of seed per 1,000 square feet when using a 50-50 mixture of ryegrass and bluegrass seed.
Disperse the seed over the prepared area until you can easily see the seeds on the soil surface. Apply more seed than you think you need to ensure the grass fills in quickly, and refer to the grass seed label for detailed seeding guidelines for the grass species used. Unless you have a very large bald patch, a broadcast spreader is not required for seeding.
Scratch the surface gently with a bow rake to work the seeds about 1/4 inch deep in the soil.
Cover the seeded area with straw to retain moisture and discourage birds from eating your seed. The area should be well covered while still allowing sunlight to pass through the straw and reach the soil.
Spray a light mist of water until the soil is moist, but not wet. Do not use a high-pressure stream because this can wash away the grass seeds. If water pools up on the surface before the soil is evenly moist, stop watering and allow the pooled water to soak in before continuing.
Water the grass seed and establishing grass with about 1 inch of water weekly or more frequently during periods of drought. The soil should remain moist, but avoid over-watering because wet soil can rot developing grass roots.