Controlling crabgrass in your lawn Some of the earliest emerging broadleaf weeds have begun to emerge. The biggest problem with weeds in turfgrass is reduced aesthetic value, although some weeds can out compete turfgrass when management is reduced. Smooth and large crabgrass, yellow foxtail, and annual bluegrass are the most frequent annual grass weeds in turfgrass. Smooth crabgrass emerges in the spring before large crabgrass. Smooth crabgrass emergence begins slowly when soil temperatures in the upper inch of soil reaches 54 degrees for seven days and moisture is available. This soil temperature occurs many times when the dogwood begin to flower and the forsythia flowers begin to fade. Visit greencastonline.com/tools/soil-temperature to track soil temperature for your area.