Successfully installing grass sod in your yard depends heavily upon proper grading and soil preparation prior to laying the sod. A healthy lawn must have the correct slope for water drainage and healthy lawn growth. Preparing the subgrade before installing grass sod takes some time and special equipment, but you'll be rewarded with a healthy, lush lawn. Remember to first remove all rocks and other debris from the area you're planning to sod.
Till the soil prior to installing the grass sod using a rototiller. Make an initial pass with the rototiller to break up the soil to a depth of about 6 to 12 inches.
Perform a rough grading of the area using a mini tractor or a lawn tractor with a plow attachment. Ensure that the soil surface is 1 to 1 ½ inch lower than sidewalks, patios, driveways and other hard surfaces.
Remove or build up soil in areas as needed to achieve a 1- to 2-percent downward slope going away from your house or any buildings (a 1- to 2-foot drop every 100 feet).
Take a soil sample from the area you're planning to sod and have it tested by your local agricultural authority or county extension service. The soil test results will let you know how much lime, fertilizer and other soil amendments you may need to apply.
Apply any soil amendments to the area and use the rototiller to work them into the soil. Spray the soil with water lightly using a garden hose with a sprayer nozzle attachment. Allow the soil to settle for 1 week.
Apply a high-phosphorous lawn-starter fertilizer to the soil. Follow the dosage instructions on the package and rake it gently into the soil surface.
Perform your finish grading by adding soil to any low spots. Rake the soil so that it's smooth. Water the soil lightly to moisten it and install your grass sod.