Thanks for your in-depth reply. You are probably right in me not
needing to thatch.

The front yard and back yard grass looked absolutely stellar until
crabgrass struck in late june, early july. In the section where there
is not crabgrass coverage, the grass looks fine.

I had Scotts come out and do my front and back yard once in may, when
they claimed to have put down pre-emergent. I then switched to Lawn
Doctor, who applied crabgrass preventer to the front only (early to mid
june). I was concerned at the time about my dog's reaction to the
chemicals, which is why I did not do the back the second time.

Even so, I was disappointed with the results. I probably cut my yard
too short, which is a lesson I learned this year. I will be vigilant
next year about how much water, how many times to cut (2x / week), and
how long to keep it (as long as possible!). I was just curious to see
when a good time to powerseed would be. The concensus seems to be late
September, so I think that is what I will do. I will be scalping the
back yard (and maybe the front) in the mean time to make sure the
crabgrass doesn't have time to grow those seed things.

Thanks again for your words.

AJ