Both seeding and sodding a lawn offer distinct benefits. Seeding rather than sodding provides the opportunity to select the most appropriate combination of grasses for a particular site. There is a great diversity of seed mixtures available, but remember the grass will only be as good as the seed that is planted. Seeding allows the tiny grass plants to grow and establish itself among the microflora in the surrounding soil rather than be transplanted from another soil source. There is no thatch layer present which may harbor harmful and unwanted diseases or insect pests.
Sodding creates an "instant" lawn; one that does not require weeks or months to fully establish. This instant lawn can prevent erosion of precious topsoil which may otherwise be removed during the establishment of a seeded lawn. A thatch layer may be present and may carry with it microflora and insects from other locations.
Both types of lawn establishment require some work and care for best results. When seeding the lawn area or seedbed needs to be watered and kept moist while the seedlings are establishing. Lack of water in the new seedbed can cause disruption and uneven patterns in the germination and establishment of the lawn. A sodded lawn also should not dry out. Sod pieces can "shrink" and cause gaps. Rooting of the sod can also be delayed. Both seeded areas and sodded areas also need to be fertilized during establishment.