Overseeding your lawn helps you keep it green all year by adding cool-season grasses over warm-season grasses, or it can help fill in bare spots in your existing lawn. A slit seeder machine reduces some of the preparation necessary when overseeding by condensing some steps. Instead of requiring you to rake over the grass to loosen the soil, a slit seeder cuts narrow furrows and drops seeds in the furrows in the same pass.
Mow the grass to a height of 2 to 3 inches. This opens up the lawn some so the seeds can fall between the blades.
Pick up items in your lawn that could impede the slit seeder, such as protruding rocks, twigs or sticks. This is a good way to get your kids involved in the overseeding process.
Pour half the bag of grass seed into the slit seeder. This helps ensure you have enough seed to make a second pass over your lawn.
Move the slit seeder to one corner of your yard. Crank the slit seeder, following the manufacturer's instructions, and set the distribution rate to 50 percent of the suggested amount for your type of seed. Each seed type has a different distribution rate, such as 10 seeds per square foot, typically listed on the outside of the bag.
Push the slit seeder at an angle across your yard. Turn it around at the other end of the yard and make a pass directly beside and parallel to your first pass, similar to the pattern you use when mowing grass. Continue until you completely cover the yard.
Refill the slit seeder with the remainder of the grass seed.
Start a second pass at a corner beside the first corner; if you started the first pass on a north-facing corner, for example, start the second pass from a west- or east-facing corner. This allows you to run nearly perpendicular to your first passes across the yard, forming a diamond pattern with the furrows.
Continue seeding across your yard until the second pass is complete.
Water the lawn thoroughly right after completing your second pass to help the seeds soak into the soil.