If you hire someone to hydroseed your lawn for you then it could cost from $2,000.00 to $7,000.00 for a professional to hydroseed the lawn.
Hydroseeding a lawn costs from around 18 cents per square foot so it would depend on how many square feet your lawn is.
You can however hydroseed your own lawn yourself for much cheaper if you know how to do the job.
If you hydroseed your lawn yourself it might only cost you around $200.00 to $300.00