There are several products that I have found to be affective for seeding bare spots in the grass, all of which are available at Lowes. Pennington makes a mesh-less thatch mat can be put down over large bare spots that have been newly seeded. The Thatch mat provides protection from driving rain, preventing the seed and new soil amendment from washing away. The mat also holds moisture in, and begins decomposing as the new grass seed grows up through it.