Hydro seeding is in inexpensive way to produce grass over a large area, when compared to sodding.
Things you should know:
Hydro seeding is price by square yard/meters.
Hydro seeding is done with in the months of May to Early October, and should not be done passed mid-October as the seeds will not have time to germinate before the onset of winter in Southern Ontario.
Hydro seeding is made up of paper pulp, water and grass seeds, this mixture binds to the topsoil and will stand up to light rains without washing way before germinatio
You should not hydro seed if there is heavy rain in the foreseeable future.