Dee wrote:

My lawn is fairly weedy. I would like to kill the weeds without harming
what grass is left (probably using a 2,4-D type spray) and then reseed in
the fall. How long do I need to wait before I reseed?

How long do you need to wait after what? After spraying? You don't need
to wait.

Also, with a little TLC, your existing grass will probably fill in without
reseeding. I was shocked last year to discover how much damage the violets
and creeping charlie had done to a patch of my lawn. I started watering it
more and pulling the weeds, and there was very little grass left. But the
grass filled in nicely before I got around to reseeding. When I got rid of
the creeping charlie and most if the violets, the grass was able to crowd
out most of the other weeds (for some reason there were no dandelions here;
I woulda spot treated them with 2,4-d if there were.) I think the creeping
charlie choked out the dandelions :-/

Bob