Skip to main content
Cover image for Crabgrass: identify it, treat it, keep it out
Weed guide

Crabgrass: identify it, treat it, keep it out

Crabgrass is the most common summer annual weed in American lawns. It germinates when soil hits the mid-50s in spring, sprawls into wide, crab-legged clumps through summer, then dies at frost and leaves bare spots that reseed next year. Prevention timing beats curative spraying almost every time.

Type
Grassy weed
Difficulty
Moderate
Strategy
Prevent or treat
Germinates at
55°F
Not 100% sure it's crabgrass?

Top pick for crabgrass

See all
  • 1
    BASF Drive XLR8 Crabgrass Killer (Quinclorac)
    Top pick

    BASF Drive XLR8 Crabgrass Killer (Quinclorac)

    Water-based quinclorac concentrate for post-emergent control of crabgrass and listed broadleaf weeds when they have already broken through. Quinclorac is the post-emergent crabgrass pick when it is safe for the grass.

    Check price

As an Amazon Associate we earn from qualifying purchases.

Why crabgrass keeps winning: the lifecycle

Understanding why this happens helps you prevent it next time. Crabgrass runs a one-year sprint: germinate in spring when soil warms through the mid 50s, sprawl and out-compete turf all summer, drop thousands of seeds per plant, then die at the first hard frost. The plant you pull in July is already gone by November either way. What persists is the seed bank, and a single neglected season can bank enough seed to keep pressure on your lawn for several years.

That lifecycle is also its weakness. Because crabgrass must restart from seed every single spring, one well-timed pre-emergent barrier interrupts the whole cycle. The plants that slip through show up first along driveways, sidewalks, and thin sunny patches because pavement radiates heat and those soils cross the germination threshold one to two weeks before the rest of the yard. If you spot-check anywhere in April, check there.

Before you build a plan around that timing, confirm the ID, because the three most common lookalikes all break it. Coarse upright clumps are often tall fescue rather than crabgrass. Clumps that return in the same spots every year are usually dallisgrass, which pre-emergent does not stop. And a spreading mat you cannot pull is probably bermudagrass, not crabgrass.

The two-season plan to get ahead of it

Season one is about the barrier: apply pre-emergent at the 55°F soil trigger, water it in within a few days, and consider a second half-rate application 6 to 8 weeks later where pressure is heavy. Spot-spray any breakthrough with quinclorac while plants are small, and mow tall all summer so sunlight never reaches bare soil.

Season two is about density. Overseed thin areas in fall (cool-season lawns) or push spreading growth in early summer (warm-season lawns), fix the compacted or droughty edges where crabgrass got its first foothold, and repeat the spring barrier. Most lawns that follow the timing for two consecutive years drop from a visible infestation to a handful of stragglers, because the seed bank finally starts to starve.

How to identify crabgrass

  • Wide, flat blades that are noticeably lighter green than the surrounding lawn
  • Stems radiate from a central point like crab legs, hugging the ground
  • Clumps show up first along driveways, sidewalks, and thin sunny spots where soil warms fastest
  • Finger-like seed heads splay from the stem tips in late summer
  • Pulls up easily as a single rosette with shallow roots

Don't confuse it: Often confused with tall fescue clumps (darker green, upright, deep-rooted) and dallisgrass (perennial, returns from the same spot each year).

Not sure this is crabgrass? Snap a photo and our AI will identify the weed with treatments matched to your grass type.

When to treat crabgrass

Prevention (pre-emergent)

Apply before germination, when soil reaches about 55°F.

Window: Late winter to early spring

Typical dates: Before soil reaches 55°F for 3 consecutive days

Treatment (post-emergent)

Best time: Early summer when young

Target stage: Before tillering (4-6 leaf stage)

Conditions: Apply when weeds are dry · No rain for 24 hours · Temps below 85°F

Germination starts around 55°F soil temperature (optimal 65°F). Track your ZIP's live soil temperature or get an exact plan from the herbicide timing calculator.

How to control crabgrass

  1. 1Apply pre-emergent before soil reaches 55°F
  2. 2Maintain thick, healthy grass to prevent establishment
  3. 3Avoid overwatering in summer
  4. 4Consider overseeding in fall to improve density

Good to know

  • Most effective as pre-emergent
  • Can be controlled post-emergent when young
  • Produces thousands of seeds per plant
  • Thrives in compacted soil

Weed control quotes

Get matched with local weed control pros on Angi. Free quotes, no obligation.

Get matched with weed control pros

Angi is a partner; we may earn a commission if you request quotes there.

Products that work on crabgrass

These picks are not filtered to your lawn. Some herbicides damage certain grasses (atrazine is for warm-season lawns; Trimec harms St. Augustine). Verify your grass type on the product label before applying, or use the herbicide timing calculator for grass-filtered recommendations.

Recommended Products

See all
  • 1
    Barricade 4FL Herbicide Concentrate (4 Fl Oz)
    Top pick

    Barricade 4FL Herbicide Concentrate (4 Fl Oz)

    Prodiamine pre-emergent concentrate for established lawns when the guide specifically calls for long-residual crabgrass prevention. The 4 oz bottle treats roughly half an acre at the standard label rate. Prodiamine prevents the next crabgrass wave before it germinates.

    Check price
  • 2
    Fiskars Stand-Up Weed Puller Tool (39 in)
    Best value

    Fiskars Stand-Up Weed Puller Tool (39 in)

    Four-claw stand-up puller for removing isolated taproot and rosette weeds without a selective herbicide. Pull isolated crowns before they produce seed without risking the surrounding turf.

    Check price

As an Amazon Associate we earn from qualifying purchases.

Where crabgrass shows up

Most common in these regions:

All regions

Sources

  1. Michigan State University ExtensionTiming crabgrass pre-emergence applications
  2. University of Maryland ExtensionCrabgrass identification and management

Frequently asked questions

When should I apply crabgrass preventer?

Apply pre-emergent when soil temperature reaches about 55°F for several consecutive days, which is usually when forsythia blooms. In most of the country that is early to mid spring. Our soil temperature tool tracks your ZIP so you can time it precisely.

Can I kill crabgrass in summer?

Yes, with a post-emergent herbicide containing quinclorac while plants are young. Mature August crabgrass is much harder to kill, and it dies at first frost anyway, so late-season spraying is often not worth it. Focus on prevention next spring instead.

Why does crabgrass keep coming back every year?

One plant drops thousands of seeds that stay viable in soil for years. Skipping pre-emergent for a single season lets that seed bank germinate. Two to three consecutive years of well-timed prevention plus a thicker lawn breaks the cycle.

Related weeds

Not sure what's in your lawn?

Upload a photo and our AI identifies the weed, disease, or pest with severity and treatments matched to your grass and ZIP.

Identify this weed free

Cover photo: Crabgrass sprawling across a pavement edge by earl woolsey, CC BY 4.0, via iNaturalist.

Still not sure what grass you have?
The free iPhone app tells you in seconds.
App Store