rw wrote:
I live in Mass and recently had my soil tested at a pH of 5.1. I had
spread lime in the Spring but apparently it wasn't enough. How much
should I add and when is the best time to apply it.

How much did you apply in Spring? Usual maximum at any one time is 50
lbs per 1,000 sq ft. My pH was similar to yours, in the 5.2 - 5.4 range
between the front and back yards. I put down about 40 lbs/1000 sq ft in
the spring and I plan to put some 50 lbs/1000 again this fall. You have
to add a good amount to have it raise it from 5.1 to say 6.

From what I understand, you have to get the lime into the soil, so for
best results either you do it when you dethatch/aerate, or you have to
work it into the soil when you amend it.

Note: I would at some point this season like to fertilize and overssed
areas of the lawn.

Lime application should help since it will raise the pH to a level good
for the grass and poorer for weeds. I overseeded the same day as I
added lime.

--
Himanshu