Common weeds at a glance
This infamous summer annual thrives in hot, moist areas. It's a shallow-rooted weed that flourishes in underfed lawns, in poorly drained areas, and in lawns and flower beds that receive frequent surface watering. Seeds germinate in early spring in southern climates, later in northern areas. As the plant grows, it branches out at the base; stems can root where they touch the soil.
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 not frequently; 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.
For chemical control in lawns and around ornamentals, use a pre-emergence herbicide such as trifluralin; apply it in late winter to early spring, depending on when crabgrass germinates in your zone (a local nursery or your Cooperative Extension Office can provide this information). For post-emergence control around ornamentals, apply fluazifop-butyl or sethoxydim.