Why Should I Put Hay on Grass Seed?
Hay prevents grass from growing in patchy. It holds sprouting seeds in place, protecting from scavengers and rainstorms that might de-seed your lawn before germination begins.
Purpose - Covering grass seeds with hay helps keep the seeds in place while they germinate and provides some protection from squirrels or birds, which might try to eat the seeds.
Alternatives - You could also use straw, soil or a grass seed accelerator that contains a blend of fertilizer and paper mulch. Any of these products will function in the same way.
Time Frame -
Typically, grass seeds will germinate within seven days and be visible within two weeks.