Scott's 4 step program worked for me as well.
The first step has a pre-emergent in it so nothing will seed.....good and bad grass alike. If it is really bad, throw it down again in early summer to ensure it holds all year.
That should give your new lawn time to fill out. Keep the grass longer and healthy, as the best preventive measure for crabgrass and other weeds is a full, healthy, deep rooted lawn.
Cap
The first step has a pre-emergent in it so nothing will seed.....good and bad grass alike. If it is really bad, throw it down again in early summer to ensure it holds all year.
That should give your new lawn time to fill out. Keep the grass longer and healthy, as the best preventive measure for crabgrass and other weeds is a full, healthy, deep rooted lawn.
Cap