Good question. Nobody really knows. Why do you want to overseed? Improved varieties? Correct thinness? Burned out during hot weather? What species or mixture of species of grass?
If you add new grass to old grass...how do you tell how much of the new actually took hold?
What soil prep did you plan? Perennial rye takes hold fairly well--much faster than bluegrass--but not everyone wants a perennial rye lawn. One thing is sure...the more seed you sow...the more new grass you will eventually have in the lawn.
I don't know about starter fert rates.
Last edited by RigglePLC; 09-01-2012 at 10:26 PM.