What to Know About Crabgrass
Crabgrass germinates in early spring when soil temperatures are 50°F–55°F or greater. Crabgrass prefers areas where preferred turfgrass is weak and unhealthy. Healthy turf is therefore the best way to prevent crabgrass infestation.
How to Prevent Crabgrass
Best practices for crabgrass control include general weed management to maintain healthy turf, such as:
- Mowing at the recommended height for selected turfgrass species
- Removing clippings when seed heads of grassy weeds are present
- Applying proper fertilization at the correct time for selected turfgrass species
- Using soil testing to determine nutrient needs and lime requirements
- Applying preemergence herbicides before the crabgrass germinates.
Where there has been a history of crabgrass infestation, apply a preemergence herbicide in late winter or early spring before soil temperatures remain above 50°F for 24 consecutive hours. In addition to initial treatment, a follow-up application made 60 days after the initial treatment is very important. Postemergence control is limited. Currently there are no labeled postemergence herbicides for selective control of crabgrass in St. Augustine grass turf.