How to Get Rid of Crabgrass in Your Lawn (Without Wrecking the Grass)

Gregory Stewart

Updated on October 23, 2026

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To get rid of crabgrass, pull or spot-treat existing plants before they set seed, then stop next year’s batch with a pre-emergent applied before the soil warms enough for germination. University extension services commonly tie that timing to soil temperature – roughly 55°F at a 2-inch depth for several days. For an established problem, use a labeled post-emergent on young plants, mow at a healthy height, and overseed bare spots so thick turf crowds out new crabgrass. Always follow the product label.

This guide draws on university extension guidance (including Nebraska and Texas A&M extension). Herbicide products vary by grass type and by state, so the product label always overrides anything written here.

Why crabgrass takes over a lawn in the first place

Crabgrass is an opportunist. It thrives in thin, stressed lawns where sunlight reaches the soil, and it likes compacted soils, dry conditions, and turf that gets scalped too short. Each plant is an annual — it germinates in spring, spreads flat across the ground over the summer, then dies after the first frost. Before it dies, a single plant can drop a very large number of seeds into your soil, and those seeds can sit there waiting to germinate next spring.

That life cycle is why crabgrass control can feel like a losing battle. You can remove the crabgrass you see this year, but if you ignore the seeds, you get more next season. Real control means doing two jobs at once: removing the existing plants now, and preventing the next generation from sprouting.

How long do crabgrass seeds stay viable in soil?

Crabgrass seeds can remain viable in soil for several years, which is why one bad summer can affect a lawn for multiple seasons. Because pre-emergent products have limited residual protection, extension sources say a single application sometimes isn’t enough for the whole season; the label tells you whether a second application is allowed and when.

How to identify crabgrass (and what it isn’t)

Before you treat anything, make sure you are actually looking at crabgrass — the wrong ID means the wrong product. Crabgrass grows in a low, flat rosette that radiates out from a central point, like the legs of a crab, which is where the name comes from. The blades are wider and lighter green than most lawn grasses, and a mature plant sends up finger-like seed heads in mid to late summer. It sprawls sideways rather than growing upright.

Several grasses get mistaken for it:

The distinction matters because crabgrass is an annual you can outlast with timing and prevention, while quackgrass and dallisgrass are perennials that regrow from underground parts — a pre-emergent aimed at seeds will not touch them. If in doubt, ask your local extension office to identify a sample.

Pre-emergent herbicide is the main chemical tool

A pre-emergent herbicide creates a barrier in the top layer of soil that stops crabgrass seeds from establishing as they germinate. It does not kill existing plants — it only works on seeds before they break the surface, so timing is everything.

Apply it in early spring, before crabgrass growth begins. The trigger is soil temperature, not the calendar. Extension guidance (Nebraska, Texas A&M) puts germination at roughly 55°F soil temperature at a 2-inch depth, holding for several days in a row. Aim to have the product down before that window opens. A soil thermometer beats guessing, and many extension services publish regional soil-temperature maps and local timing advice.

Two active ingredients commonly named in extension materials are prodiamine and dithiopyr. Nebraska extension materials note prodiamine’s long residual, and that dithiopyr also has early post-emergent activity on crabgrass seedlings at the one- to three-leaf stage. Control gets harder once plants start to tiller. Check the label for your grass type, application rate, and watering-in instructions.

When pre-emergent won’t work

Pre-emergent is useless on crabgrass that has already sprouted. It also blocks any seed, so you generally cannot apply it and seed new grass in the same window; the label will say how long to wait before seeding. If you plan on overseeding or starting a new lawn in spring, skip the pre-emergent that season and rely on post-emergent control and good mowing instead. (Curious how long grass takes to fill in after seeding? See how long it takes for grass seed to grow.)

How to kill crabgrass that’s already growing

For crabgrass that is already up, you need a post-emergent product labeled for crabgrass and for your grass type. Post-emergents work best on young plants; mature, sprawling crabgrass often survives a single application, which is a common reason people think post-emergents “don’t work.” On a small patch, spot-treat rather than treating the entire lawn, and follow the label exactly so you don’t stress your existing grass. The label sets the rate, the weather conditions, whether a repeat application is allowed, and how long to keep kids and pets off the area.

I’m not naming specific post-emergent active ingredients here, because which ones are safe depends heavily on your grass species (for example, products that suit tall fescue can injure St. Augustine or centipede). Buy by what the label says about crabgrass and your grass type, and ask your local extension office if you’re unsure.

Pulling individual crabgrass plants by hand

For a few scattered plants, hand-pulling is the fastest fix. Water first so the soil is soft, grip low at the base, and pull steadily so the roots come out whole. A long-handled weeding tool saves your back on bigger areas. Pull before the plant goes to seed and you stop that plant from adding to the seed bank.

Natural methods that actually do something

You do not always need chemicals. The most reliable non-chemical method is a healthy lawn: dense, properly mowed turf shades the soil so crabgrass seeds don’t get the light and warmth they need to germinate. Beyond that, a few methods help on small spots.

• Boiling water. Pour it directly onto individual plants in driveway cracks, along sidewalks, and lawn edges. It is non-selective, so keep it off the grass you want to keep.
• Horticultural vinegar. Strong vinegar products can scorch young crabgrass but only top-kill it, so expect regrowth from the roots. It is non-selective, and the product label covers eye and skin protection.
• Smothering / solarization. Cover a stubborn small patch with cardboard, or a sheet of clear plastic in full sun, for several weeks, then rake out the dead material and reseed.
• Hand removal. Boring, free, and effective on the plants you actually pull.

Boiling water and hand-pulling are spot tools; they won’t clear a large, heavily infested lawn. For that, prevention plus a timed pre-emergent does the heavy lifting.

When to skip herbicides entirely

There are cases where a herbicide is the wrong call. Skip it if you are seeding new grass that season, if you would simply rather not spray where kids or pets play, or if the crabgrass is confined to a small patch you can pull in ten minutes. Herbicides also do little in late summer once plants have already set seed — the seeds are already in the ground, and your effort is better spent on a fall overseeding plan.

How to prevent crabgrass before it starts

The cheapest way to deal with crabgrass is to prevent it. Prevention rests on two ideas: stop germination at the soil surface, and build turf so dense that weed seeds never find the light to thrive. A timed pre-emergent handles the first; thick grass handles the second.

Warm-season and cool-season lawns green up at different times, so adjust your timing to your grass type and region rather than a fixed date. If you are starting from scratch with sod, fresh sod knits into a dense mat and leaves little open ground for weed seeds.

Build a healthy lawn so crabgrass can’t come back

The best long-term crabgrass control is cultural, not chemical. Crabgrass is a symptom of thin turf, so the fix is thick turf.

Mow at a healthy height

Mow at the recommended height for your grass species, toward the taller end of the range in summer. Taller grass shades the soil surface, which helps limit crabgrass germination. Mowing too short opens the canopy and favors crabgrass.

Water deep, not often

Deep watering encourages roots to grow down and builds drought tolerance. Frequent shallow watering keeps the soil surface moist, which favors weed seed germination. Water deeply once or twice a week rather than a little every day.

Aerate compacted soil

Crabgrass tolerates hard, compacted ground where desirable grass struggles to root. Core aeration (early fall for cool-season grass, late spring for warm-season) relieves compaction so turf roots deeper and fills in thin spots. It pairs well with overseeding, because the holes give new seed direct soil contact. If you’ve applied a pre-emergent, check the label before aerating, since deep soil disturbance can break the herbicide barrier.

Overseed bare spots in early fall

Bare patches are open invitations for weeds. Overseeding in early fall fills them before winter so you start spring with a denser lawn. Choosing the right grass for your conditions matters too — if your lawn struggles under trees, a shade-tolerant blend like those in our guide to the best grass seed for shade will establish thicker turf where crabgrass often wins.

Crabgrass timing cheat sheet

Crabgrass control is mostly about doing the right thing in the right season. Here is the year at a glance.

For a stand-alone pre-emergent, you can browse crabgrass pre-emergent granules on Amazon; read the label for your grass type and application timing. Grubs are another common cause of thin, weed-prone turf — see our pick for the best grub killer for lawns if you spot dead patches that peel up like carpet.

FAQ

What is the fastest way to get rid of crabgrass?

For visible plants, the fastest route is hand-pulling a small patch or spot-treating young crabgrass with a labeled post-emergent. But “fast” and “permanent” are different: keeping it gone takes a pre-emergent next spring plus thicker turf.

Does crabgrass die on its own in winter?

Yes. Crabgrass is a warm-season annual, so it dies at the first frost. The problem is the seeds it leaves behind, which is why prevention the following spring matters more than fighting dying plants in fall.

Will mowing get rid of crabgrass?

Mowing alone won’t kill crabgrass, but mowing at a healthy height helps prevent it. Taller grass shades the soil so fewer seeds germinate. Mowing too short makes a crabgrass problem worse.

Can I put grass seed and crabgrass pre-emergent down at the same time?

Generally no. A pre-emergent stops seeds from germinating, including new grass seed. Wait until the new lawn is established, or use a product whose label specifically allows use at seeding.

What’s the difference between crabgrass and other lawn weeds?

Crabgrass is a grassy annual weed that spreads flat in a star shape, unlike broadleaf weeds. If you are fighting clover instead, the approach is different — see our guide on how to get rid of clover in the lawn, since a crabgrass pre-emergent won’t treat clover.

How do I get rid of crabgrass permanently?

There is no one-and-done fix, because seeds in the soil can remain viable for years. Long-term control is a routine: a pre-emergent each spring at the right soil temperature, spot-treating or pulling any plants that slip through, and keeping the turf thick with healthy mowing, fall overseeding, and aeration. Over several seasons the seed bank shrinks.

Does mowing crabgrass spread it?

Mowing over plants that have already formed seed heads can scatter seed across the lawn. If crabgrass has gone to seed, bag the clippings for those passes and keep mowing at a healthy height for the rest of the season.