For the last two years we have had serious crab grass problems. Last Fall we had our front lawn torn up, had it hydroseeded, and installed irrigation. The new lawn looked great last Fall, but the crabgrass came back over the summer. Although not quite as bad as last year, there is quite a bit. We have had a professional landscape company do all of the fertilizing, but I'm ready to give up on them. Two weeks ago, I aerated the whole lawn and applied a Fall fertilizer. I'm wondering... 1. Should I de-thatch the whole yard and try and remove all the crab grass this Fall, wait until Spring, or not bother with this step? 2. Reading different threads, people recommend a pre-emergent in mid-March - which product would you suggest? (I do have a Lesco about 25minutes away). How many applications, and how far apart? 3. Should I slice seed in the Spring (too late now, I would imagine)? Any other suggestions would be appreciated! Thanks.