Large crabgrass is the most common summer grassy weed in Oklahoma lawns. It sprouts in spring, spreads flat in thin areas, and dies at the first frost after dropping thousands of seeds.
- Scientific name
- Digitaria sanguinalis
- Type
- Summer annual grass
- Most visible
- June–September
How to Identify Large Crabgrass
- Wide, light-green blades with fine hairs
- Stems spread outward from a central point like a crab
- Finger-like seed heads in mid to late summer
- Roots at the stem joints where they touch soil
When It Shows Up in Oklahoma Lawns
Seeds germinate when soil temperatures stay in the mid-50s °F, often in March or April in central Oklahoma. It thrives along driveways, sidewalks, and anywhere turf is thin or scalped.
How to Control Large Crabgrass
- Apply a pre-emergent before seeds germinate (late winter for summer annuals, early fall for winter annuals)
- Pull young plants before they set seed
- Spot-treat with a selective herbicide labeled for the weed and safe for your grass type, following the label exactly
- Keep turf thick with proper mowing height, watering, and feeding so seedlings can't establish