In flower beds, pull crabgrass before it sets seed. To thwart crabgrass in lawns, keep the turf well fertilized and vigorous, so it will provide tough competition for weeds. Also water your lawn deeply, but infrequently; this tactic will dry out crabgrass roots, killing the weeds or at least diminishing their vigor. Solarization can control crabgrass if high temperatures are achieved.
Use corn gluten as a preemergence treatment. If chemical control is necessary, in ornamental beds only, use a postemergence herbicide control that kills grasses.