A new lawn, or a lawn with too many shade trees, can require overseeding to adequately grow. Because seeding a lawn comes with unavoidable hazards like birds eating the seeds and dead seeds, you need to overseed the lawn, so enough seeds remain to take root. Incorrectly seeding your lawn results in spotty grass patches or none at all. Additionally, if you don't prep the newly seeded lawn properly, your lawn might remain in a state you don't want -- a smooth section of dirt. Correctly seeding your lawn helps you grow your grass into a luxurious lawn you and your family can take pride in.
Mow your lawn in early autumn to within 1/2 inch, if your mower's blade will adjust to that measurement. If it won't, mow your lawn to the lowest depth. Overseeding in autumn eliminates most lawn weeds, which have already run their season, so your new seeds don't have to compete for soil nutrients.
Rake your lawn using the grass rake to a depth of approximately 1/8 inch, bagging all debris like sticks, twigs or leaves. The debris creates a barrier between the seed and the soil, so the seeds won't germinate. Your old grass must have as much space between the blades as possible to allow for growth.
Core aerate your yard using the core aerator, which pulls small sections of your lawn up, so new seeds can take root. The process might seem analogous to hair plugs for balding people, and the grass seedlings fill in evenly like grass plugs across your yard.
Check a core aerated sample that your aerator uprooted to see if the grass consists of thick, rough grass stems or thin, fine ones. You need to purchase fescue seeds to match thick, rough grass or bluegrass seeds for fine grass.
Scatter the seeds throughout your lawn by hand, using about 2 to 4 lbs. per 1,000 square feet, or if you have a larger yard, use the rotary seeder, which scatters seeds more consistently. For sparse lawns needing heavy overseeding, use 8 to 10 lbs. of seed per 1,000 square feet. This seed coverage will provide a layer of seeds capable of withstanding birds, and will seed your lawn in sufficient numbers to account for the percentage of dead seeds that all seed batches contain. While seeding, walk back and forth across your lawn in straight rows, to ensure you seed your entire lawn.
Water your seeded lawn using the sprinkler, set to early morning and dusk. You must keep your grass damp until the seeds germinate and sprout new growth. So, you might need to water three times per day or more if the grass, or soil, feels more dry than damp. Additionally, the cool air during autumn helps keep the grass moist.
Distribute a moderate amount of straw across your yard to create patches or holes within the straw, approximately 2 to 4 inches wide. If you lay the straw and can step between the strands, then you need more straw. If the entire yard looks blanketed by straw, rake it and thin it out.