The Best Liquid Crabgrass Killer Concentrates to Keep your Lawn Weed-Free

By: Ken Wilson

Before you know it, crabgrass may destroy your picture-perfect green lawns and lush gardens if you overlook the problem at hand. If you're wondering why it's named as such, its growth is similar to that of a crab. It grows low to the ground with stems, growing out of the center of the clump of grass.

This annual weed is a common homeowner frustration every year. So if you are dealing with crabgrass problems at home, you may want to act on the matter ASAP before things go out of control.

Here are some of our proven and tested products to use against pesky crabgrass:

The adage "prevention is better than cure" applies when dealing with persistent crabgrass on your lawn. This first liquid crabgrass killer concentrate is from Scotts, a notably leading brand in the industry.

The Halts Crabgrass and Grassy Weed Preventer is designed to efficiently prevent weed seeds from germinating during the spring and fall. It is also safe to apply for all established lawn types.


Ideally, apply this herbicide during the early spring with a dry lawn to prevent possible crabgrass germination (along with other common weeds).

If you apply the pre-emergent when the lawn is dry, you won't need to worry about rain, snow, or freezing conditions. It won't affect the performance of the product in any way. A reapplication in the fall will help prevent winter weed germination, such as annual bluegrass and chickweed.

Important Note: Since it is a pre-emergent, this product won't kill mature crabgrass. Instead, it will prevent the seeds from germinating.

Another effective crabgrass killer and preventer combination is Tenacity. Applying it on the affected lawn before spring will prevent the germination of grass weeds, and it can also kill full-grown weeds in the summer.

What we love about this product:

  • It is a 2-in-1 formula (for both pre and post-emergent needs)
  • Effectively kills crabgrass without killing the rest of the lawn grass. However, if you're applying it on Bermuda grass, it's only advisable to do so once it's dormant.
  • List Highly effective on other turf weeds
  • Can kill persistent crabgrass to the root

The Southern Ag brand is another reputable name in insecticides, fungicides, and herbicides. This product has the active ingredient atrazine, which can be used on St. Augustine and crabgrass lawns. You can apply the weed killer in either dormant or growing seasons. But for best results, use it during the early spring or inactive periods as weeds are less likely to be fully developed. As per the manufacturer's guidelines, only limit the application to two times a year.

If you have sensitive Zoysia grass at home, Ortho's Weed Be Gon Plus Crabgrass Concentrate is an excellent post-emergent herbicide to eliminate crabgrass without damaging the existing lawn. In particular, it targets broadleaf and grassy weeds. It's known to work best on warm-season grasses that require substantial weed control.

For severe crabgrass infestations, you may want to wait until the spring or fall and apply a pre-emergent herbicide. Keep in mind that this product gives the best results when used on small, active weeds and a dry lawn.

The formula of this product is effective on crabgrass and other lawn weeds, consisting of 2,4-d, dicamba, dimethylamine salt, and quinclorac. All of these ingredients are good at getting rid of grassy weeds.

You can expect noticeable results as fast as 48 hours. After an entire week, all crabgrass will be removed for good.

One downside is its tricky application process. It would be best to be careful not to apply the Green Light Crabgrass Killer on good grass, as it may only damage it. Aside from crabgrass, this product is also effective on over 250 common lawn weeds.

Preen is another crowd-favorite brand when it comes to residential weed control. It is considered safe for more than 200 shrubs and flowers. The Garden Weed Preventer works best when applied in the spring, once you spread mulch on flower and shrub beds.

This product blocks other broadleaf garden weeds, including chickweed and knotweed, and common grassy garden weeds such as bluegrass.

With 41% glyphosate to exterminate crabgrass and other lawn weeds, the Compare-N-Save concentrate grass and weed killer is another excellent option. The concentrated formula can cover minor to medium-sized lawn weed control needs.

Expect to see noticeable results in 2 to 4 days. You can apply it on affected driveways or walkways, garden fences, flower beds, and shrubs. Be careful with its application, though. This powerful solution will kill every grass it touches, and you may want to save your good, thriving grasses in some cases.

This water-based liquid formula wipes out crabgrass and other common lawn weeds. For your reference, one bottle will suffice to treat an entire acre.

This product is an excellent choice for spot treatment, and it gives quick, visible results. Most homeowners say a single treatment is enough to control unwanted crabgrass growth. Spray it on the affected area and wait for a few days until the leaves deteriorate.

It is also designed with a quick-dry formula, so you won't need to keep the kids and pets away during the treatment process for safety purposes. This also means you don't need to worry about the weather condition.

Another Ortho product for crabgrass control is the Weedclear lawn weed killer. Like other products, it is also effective to use on common lawn weeds, such as chickweeds and dandelion. One application will cause the weed to wither and die away. Also, it gets rid of the weed down to the roots without causing harm to your lawn.

The product also ensures easy application as it comes ready to spray. Connect the sprayer to your garden hose, and turn on the water to start! To ensure the best results, apply it during the spring and fall when most new lawn weeds are still developing.

Frequently Asked Questions

What is crabgrass?

Crabgrass is a well-established weed that thrives on lawns and spreads rapidly. It's an annual weed that grows during the summer, but it's a prolific seeder. Each crabgrass plant may produce up to 150,000 seeds, which germinate and repeat the cycle the following season.

When is the best time to apply crabgrass pre-emergent?

When the soil temperature is approximately 50 degrees, apply crabgrass pre-emergent. A second spray may be required to eliminate the weed in places with extended growth seasons completely. Timing should be done according to the manufacturer's instructions.

Will heavy rain wash away the pre-emergent?

No. Pre-emergent is activated by rain because it is carried into the soil. However, after applying the pre-emergent, any digging and plucking of existing weeds might reduce the product's effectiveness.

How do I apply a crabgrass killer?

On a dry day, apply post-emergent crabgrass killer in the morning. Only treat the lawn's damaged areas. Evenly coat the crabgrass.

About the author 

Ken Wilson

Long time career in the home services industry from remodeling to patio construction. Currently residing to in SWFL and active contributor to multiple home & garden publications.