Crabgrass: How to Identify and Control It
Digitaria spp. · Summer annual grass
How to identify crabgrass
- Light green, coarse blades wider than most lawn grasses
- Low, spreading clumps; stems root at nodes and radiate like a crab’s legs
- Finger-like seed heads in mid-to-late summer
- Dies with the first hard frost, leaving bare patches
Why it shows up
Thin turf, scalped mowing, and bare soil in full sun. Seeds germinate in spring once soil reaches roughly 55°F for several days.
Control methods
1. Cultural (prevention)
- Mow higher (about 3–4 in. for cool-season lawns) to shade the soil
- Overseed thin areas in early fall so turf fills gaps
- Water deeply and infrequently
2. Mechanical
- Hand-pull young plants before they set seed
- Pull before the root system spreads
3. Organic options
- Corn gluten meal is sold as an organic pre-emergent; research results on its effectiveness are mixed
4. Chemical options
Herbicide safety: The label is the law. Use only products labeled for your site and grass type, follow rate, timing, and weather directions exactly, wear listed protective equipment, keep people and pets off treated areas as directed, and check state and local rules. Active ingredients named here are examples, not endorsements.
- Pre-emergent herbicides (e.g., products with prodiamine, pendimethalin, or dithiopyr) applied before germination — often timed around when forsythia finishes blooming
- Post-emergent products labeled for crabgrass in your grass type for escaped plants
- Pre-emergents also stop grass seed; don’t apply where you plan to overseed soon
When to treat crabgrass in the Mid-Atlantic
Prevention is all about timing: apply a pre-emergent when soil reaches about 50–55°F for several days — usually around forsythia bloom, roughly 2–4 weeks before your last spring frost date (late March in Tidewater VA and coastal areas, mid-to-late April in the Piedmont and central PA). Pull escapes before they seed in late summer.
Frequently asked questions
How do I get rid of crabgrass naturally?
Start with cultural and mechanical controls: Mow higher (about 3–4 in. for cool-season lawns) to shade the soil; Overseed thin areas in early fall so turf fills gaps; Water deeply and infrequently; Hand-pull young plants before they set seed; Pull before the root system spreads.
What does crabgrass look like?
Light green, coarse blades wider than most lawn grasses; Low, spreading clumps; stems root at nodes and radiate like a crab’s legs; Finger-like seed heads in mid-to-late summer; Dies with the first hard frost, leaving bare patches.
More weed guides
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Planning your garden? See when to plant in Delaware and our state planting calendars.