What is the difference between seeding and over-seeding?
Seeding is starting from scratch – this requires tilling or heavy discing to loosen the soil in preparation for the seed distribution and fertilization. Over-seeding is primarily used when you already have some grass and just want to improve or thicken the stand. When over-seeding, all that is needed with regards to soil prep is a light disc or drag to loosen the soil enough to accept the seed without tearing out the existing grass.