Sod is a hefty investment, so it is critical to prepare the planting area and tend the turf with care. You can lay sod anytime during the growing season, although spring and early autumn are best because cool temperatures combined with occasional rain help sod quickly root.
If you lay sod in summer, water at least once a day for several weeks. Begin by preparing the soil. Remove twigs, stones, and other debris littering the surface. Break up soil clods that are larger than 2 inches in diameter. Fill low areas with good quality topsoil. If the soil is sandy or full of clay, work in organic matter. Take advantage of this opportunity to improve the soil; it's easy to add amendments when the soil is bare. Smooth the soil with a stiff garden rake. Finish preparing the area by compacting it slightly with a sod roller (often available through your local landscape equipment rental outlet).
Lay sod on a cool, overcast day to minimize plant stress. If you lay sod in the heat of summer, moisten the surface of the planting area before putting down the turf. With the help of a few friends, you can get the sod down in a hurry and have fun along the way. Stagger strips in a bricklike pattern, and be sure that all pieces fit tightly together. A utility knife or sharp spade is handy for cutting sod to fit irregular areas.
Once the sod is in place, run the sod roller over it to eliminate air pockets. Water it immediately, then water daily (depending on rainfall), moistening the soil to a depth of 4 inches, until the sod takes root (in 2-3 weeks). Avoid mowing sod until it has firmly rooted. To find out if sod has rooted, gently tug at it. If you feel resistance, roots are anchored in the underlying soil.