Keep the new lawn moist until grass is established. Then water as usual. If you have really tough weeds, such as Bermuda grass, you may have to spray again in a few weeks to kill them completely. It will be easiest to use a dethatcher and aerator if the ground is lightly moist, not soggy or dry. Adjust the depth of the dethatcher blades to match the thickness of the thatch.
Most herbicides work best if sprayed during hot weather.
Many herbicides will kill any plant they touch, so avoid spraying on windy days. Flag below-ground sprinklers before operating equipment. Otherwise, you may damage them. Inc. How things get done. Use of this Web site constitutes acceptance of the eHow Terms of Use and Privacy .