How to Get Rid of Crabgrass: A Complete Control Guide

If you’ve ever watched a thick, healthy lawn slowly get taken over by coarse, spreading clumps of grassy weeds, you already know how frustrating crabgrass can be. It shows up uninvited every summer, spreads aggressively, and dies off in the fall — leaving behind bare, ugly patches that invite even more weeds the following year. The good news: crabgrass is one of the most controllable weeds in the lawn care world, as long as you understand how it works and attack it at the right time.

This guide covers everything you need to know about how to kill crabgrass, when to apply a crabgrass preventer, which products actually work, and how to keep your lawn thick enough that crabgrass never gets a foothold in the first place.

What Is Crabgrass and Why Does It Spread So Aggressively?

Crabgrass (Digitaria sanguinalis and Digitaria ischaemum) is a warm-season annual grassy weed that germinates from seed each spring, grows explosively throughout summer, and dies with the first hard frost. The problem is what happens before it dies: a single crabgrass plant can produce up to 150,000 seeds in a single growing season. Those seeds drop into your soil and lie dormant all winter, ready to germinate again the following spring.

Crabgrass thrives in conditions that stress out your desirable lawn grasses:

Thin or bare spots in the lawn give seeds direct access to warm soil and sunlight
Compacted soil limits root development of grass but doesn’t slow crabgrass down
Low mowing heights stress turf and expose soil to sunlight, which triggers germination
Dry summers weaken cool-season grasses while crabgrass — a heat-loving plant — keeps growing

Understanding this cycle is key: you’re not just killing a plant, you’re trying to break a multi-year seed bank buildup in your soil.

Identifying Crabgrass vs. Look-Alike Weeds

Before you treat, make sure you’re actually dealing with crabgrass and not one of its common lookalikes. Misidentification leads to wasted product and continued spreading.

True Crabgrass Characteristics

Leaves: Wide, flat blades (wider than most lawn grasses), light green to yellowish-green
Growth habit: Grows in a low, spreading rosette pattern that “crabs” outward from a central point — hence the name
Stem: Lies flat along the ground, with nodes that can root where they touch soil
Seed heads: Finger-like spikes radiating from a central point, appearing in mid-to-late summer
Season: Annual — emerges in late spring, dies after frost

Common Lookalikes to Know

Goosegrass (Eleusine indica) is frequently confused with crabgrass. It grows in a similar flat rosette but has a distinctive silver or whitish center where the blades meet the stem. Goosegrass also tends to appear in more compacted soils and germinates a bit later in the season than crabgrass.

Annual Bluegrass (Poa annua) is a cool-season annual that looks completely different in texture — finer, lighter green, with small seed heads — but gets confused with crabgrass by beginners.

Quackgrass is a perennial with wider blades but has clasping auricles (ear-like projections) at the leaf base and creeping rhizomes underground. It won’t be killed by crabgrass preventers since it’s a perennial.

When in doubt, pull a plant and examine the base. Crabgrass has no rhizomes and no clasping projections — just a fibrous-rooted, low-spreading annual.

Pre-Emergent Herbicide: The #1 Way to Stop Crabgrass

The most effective way to control crabgrass is to prevent it from germinating in the first place using a pre-emergent herbicide. Pre-emergents work by creating a chemical barrier in the top layer of soil that inhibits seed germination and root development. They do not kill existing plants — they stop new ones from establishing.

The 55°F Soil Temperature Trigger

Timing is everything with pre-emergents. Crabgrass seeds begin germinating when soil temperatures at the 2-inch depth reach and sustain 55°F for several consecutive days. Apply your pre-emergent too late and seeds will already be sprouting. Apply too early and the product may break down before germination begins.

A reliable rule of thumb: apply your crabgrass preventer when forsythia bushes finish blooming in your area, or when soil temps hit 50–53°F (giving you a small buffer before the 55°F trigger). You can monitor soil temperature with an inexpensive soil thermometer — a worthwhile investment for any serious lawn care enthusiast.

Recommended soil thermometer: The AcuRite Digital Soil Thermometer (available on Amazon) gives accurate readings in seconds and takes the guesswork out of timing.

Regional Timing Windows

Southeast (zones 8–9): Late February to mid-March
Transition Zone (zones 6–7): Mid-March to mid-April
North/Midwest (zones 5–6): Early April to early May
Pacific Northwest: Mid-March to mid-April (varies widely by elevation)

Top Pre-Emergent Products for Crabgrass

1. Scotts Halts Crabgrass & Grassy Weed Preventer

Scotts Halts is one of the most widely available and beginner-friendly granular pre-emergents on the market. Its active ingredient is pendimethalin, which creates a soil barrier against crabgrass and many other grassy annual weeds.

Best for: Homeowners looking for an easy-to-apply granular product
Coverage: Up to 5,000 sq ft per bag (check label for your specific size)
Pros: Widely available, well-documented, safe for established cool-season and warm-season grasses
Cons: Requires watering in to activate; may need two applications in high-pressure areas

2. Dimension (Dithiopyr) Herbicide

Dimension is a professional-grade pre-emergent with the active ingredient dithiopyr. It’s unique because it also offers some early post-emergent activity on very young crabgrass seedlings (1–2 leaf stage), giving you a small window of forgiveness if your timing is slightly off.

Best for: Homeowners who want professional-grade results and slight post-emergent flexibility
Forms available: Liquid concentrate and granular formulations (look for Ferti-lome or Hi-Yield Dimension products on Amazon)
Pros: Dual pre/early post-emergent activity; excellent residual control
Cons: Costs more than basic products; liquid requires a sprayer

3. Barricade (Prodiamine) Herbicide

Barricade, with the active ingredient prodiamine, is the longest-lasting pre-emergent available to homeowners. A single application can provide season-long control in many regions, which makes it extremely cost-effective.

Best for: Larger lawns or areas with historically heavy crabgrass pressure
Forms: Granular (Hi-Yield Turf & Ornamental Weed & Grass Stopper) or liquid (Gordons Barricade)
Pros: Longest residual of any common pre-emergent; excellent value per square foot
Cons: Must be applied before germination — no post-emergent activity whatsoever

Applying Pre-Emergent: Getting the Coverage Right

Pre-emergents only work if they form a continuous barrier. Gaps in coverage = gaps in protection. Follow these tips:

Calibrate your spreader before applying. Walk the spreader at your normal pace across a tarp, collect the product, and weigh it to confirm you’re hitting the label rate.
Apply in two passes at half-rate in perpendicular directions for even coverage.
Water in immediately after application (or apply before rain). Most granular pre-emergents need ¼–½ inch of water to activate.
Don’t aerate after application — core aeration breaks the chemical barrier.

Recommended spreader: The Scotts Turf Builder EdgeGuard Mini Broadcast Spreader (Amazon) is an affordable, reliable option for most residential lawns. For larger properties, step up to the Earthway Commercial Broadcast Spreader.

Post-Emergent Herbicides for Existing Crabgrass

If crabgrass has already emerged and is actively growing, you need a post-emergent herbicide that targets grassy weeds without harming your desirable lawn grass. This is trickier than pre-emergent control because most broadleaf weed killers won’t touch grassy weeds — and non-selective herbicides (like glyphosate/Roundup) will kill everything.

Quinclorac-Based Products

Quinclorac is the most widely available post-emergent active ingredient for crabgrass control and is found in several consumer products:

Drive XLG (professional): Highly effective on large crabgrass; can be mixed with a methylated seed oil (MSO) adjuvant for best results
Ortho Weed B Gon Plus Crabgrass Control: Consumer-friendly, ready-to-spray format; active ingredient includes quinclorac. Works best on young plants.

Important caveat: Quinclorac is less effective on mature crabgrass (past the 4–5 leaf stage) and is not safe for use on St. Augustine, centipede, or certain fine fescues. Always read the label.

Fenoxaprop (Acclaim Extra)

Fenoxaprop (sold as Acclaim Extra) is a grassy-weed post-emergent commonly used by lawn care professionals. It’s highly effective on crabgrass at multiple growth stages and is safe for most cool-season grasses (Kentucky bluegrass, tall fescue, perennial ryegrass). It is not safe for warm-season grasses.

Fluazifop (Fusilade II)

Used primarily in ornamental bed situations to kill crabgrass and other grassy weeds without harming broadleaf ornamentals. Not labeled for use in lawns but worth knowing if crabgrass is encroaching into mulched beds or landscape areas.

What About Pulling by Hand?

For small infestations — a plant here and there — hand-pulling works fine, especially after rain when the soil is loose. Pull before seed heads form to prevent seed spread. The problem is the extensive root system crabgrass develops by mid-summer; at that point, pulling often leaves roots behind that re-sprout.

Organic and Natural Crabgrass Control Options

If you prefer to avoid synthetic herbicides, there are effective organic options — though they generally require more consistent effort and perfect timing.

Corn Gluten Meal

Corn gluten meal (CGM) is a byproduct of corn milling that acts as an organic pre-emergent. It inhibits root formation in germinating seeds without harming established plants. It also adds nitrogen to the soil (10% N by weight), which is a nice bonus.

Application rate: 20 lbs per 1,000 sq ft
Timing: Same as synthetic pre-emergents — before soil hits 55°F
Important: CGM must dry out after application to be effective. If rain comes within 3 days, re-apply. It takes 2–3 years of consistent use to build meaningful suppression.
Where to buy: Jonathan Green Organic Weed Preventer (Corn Gluten) and Espoma Organic Weed Preventer are both solid choices on Amazon.

Improve Lawn Density

The most sustainable long-term organic control strategy is simply growing a lawn thick enough that crabgrass can’t compete. Dense, healthy turf shades out germinating crabgrass seeds and leaves no bare soil for them to establish.

Overseed bare patches every fall (for cool-season lawns) or spring (for warm-season)
Topdress with compost to improve soil structure and seed-to-soil contact
Core aerate annually to relieve compaction and improve root depth

Cultural Prevention: The Long Game

Chemical controls work best when paired with smart cultural practices that make your lawn naturally resistant to crabgrass.

Mow at the Right Height

Never cut cool-season grasses below 3 inches. Taller grass shades the soil, keeping it cooler and making it much harder for crabgrass seeds to get the sunlight they need to germinate. Set your mower to 3–4 inches for Kentucky bluegrass, tall fescue, and perennial ryegrass.

Don’t Overwater

Shallow, frequent watering promotes shallow root systems in your lawn grass while encouraging crabgrass. Instead, water deeply (1 inch per session) and infrequently (once or twice a week). This trains grass roots to grow deeper and improves drought resistance.

Overseed Bare Spots Immediately

Every bare patch is an open invitation for crabgrass. After removing weeds or recovering from disease, overseed immediately and keep the area moist until germination. Don’t wait — crabgrass doesn’t.

Fertilize Properly

Apply nitrogen fertilizer according to your grass type’s schedule. Cool-season grasses benefit most from fall fertilization (September–November), not spring. Heavy spring nitrogen feeding encourages top growth at the expense of roots and can stress turf heading into summer — exactly when crabgrass pressure peaks.

Crabgrass Control: A Season-by-Season Plan

Season	Action
Early Spring (soil at 50°F)	Apply pre-emergent herbicide; water in
Late Spring (post-emergent if needed)	Spot-treat any emerging crabgrass with quinclorac-based product
Summer	Mow high, water deeply, don’t skip a mowing
Late Summer/Fall	Overseed bare patches left by dying crabgrass; apply starter fertilizer
Fall	Core aerate; topdress with compost; apply fall fertilizer

Conclusion

Getting rid of crabgrass for good isn’t a one-season project — it’s a combination of hitting the pre-emergent window every year, cleaning up any plants that slip through, and building a lawn thick and healthy enough to win the competition for space. The single biggest mistake most homeowners make is missing the pre-emergent timing window. Get a soil thermometer, watch your soil temp in early spring, and apply your crabgrass preventer before that 55°F threshold arrives.

With products like Scotts Halts, Dimension (dithiopyr), or Barricade (prodiamine) in your arsenal — and a commitment to mowing high and overseeding bare spots — you can have a crabgrass-free lawn within one to two seasons.

Don’t let one missed window turn into another 150,000 seeds. Get ahead of it this spring.