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Is Tenacity effective for controlling crabgrass?

Crabgrass is one of the most common weeds that affect lawns, and it is also very stubborn to get rid of.

Usually, you eliminate crabgrass by mechanical means (pulling), which is quite hard, or culturally controlled, which is not 100% effective.

Using a herbicide can increase effectiveness, but some herbicides either don’t work or do so but damage your lawn in the process.

So, which is the best way to kill crabgrass? Tenacity is one of the ideal herbicides for dealing with crabgrass and a range of other weeds. It works as a pre-and post-emergent herbicide, thus offering maximum protection against weeds.

According to several tenacity herbicide reviews, the weed killer also acts without harming the lawn or other crops.

So, is Tenancity effective at controlling crabgrass? Before we answer this question, you need to know how it works.

How does Tenacity work?

Tenacity herbicide is a weed killer that is manufactured by Syngenta. It contains 40% Mesotrione as the active ingredient used to kill crabgrass and other weeds.

It does so by inhibiting photosynthesis in the target weeds, preventing them from growing. Ultimately, this kills the weeds completely, eradicating them from your lawn.

However, what makes Tenacity effective at killing crabgrass is not the active ingredients but its methods of operation.

First of all, it is both a pre-and post-emergent herbicide. Pre-emergent herbicides attack the target weeds when they are sprouting, killing them even before they emerge from the soil.

Using pre-emergent herbicides is the best way to control crabgrass, which sprouts from new seeds yearly.

Crabgrass in lawn
Image: Yesim Sahin

On the other hand, post-emergent herbicides attack weeds once they have germinated. Since Tenacity offers both options, you can target crabgrass before it emerges and any residual weeds that survive the first application.

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The other bonus of using Tenacity is that it is a systemic herbicide instead of a contact-only herbicide.

Therefore, once it is applied to the target weeds, it will be absorbed from the point of contact, spreading to the leaves, stem, and roots, thus killing the entire plant.

On the other hand, contact-only herbicides work on the point of contact, meaning that part of the weeds may survive.

How to use Tenacity on crabgrass

Using Tenacity to kill crabgrass is quite simple. But, first, you need to decide whether you will use it at the pre-or post-emergent stages (though you can use it at both stages for increased results).

Next, you need to select the application tool, for example, a pressurized hydraulic sprayer, a high-volume handgun sprayer, a backpack sprayer, or a handheld sprayer.

Your choice of sprayer will depend on the size of your lawn, method of application, and comfort.

For example, a pressurized or backpack sprayer is ideal for dealing with a large lawn where you spray the entire area. However, a handheld sprayer will do fine if you spot a small lawn.

This guide for choosing pump sprayers should come in handy. You can also opt for a battery-powered sprayer which is quicker and more efficient.

Once your tools are ready, you can proceed to the spraying process. Below is a step-by-step guide on how to go about this:

  • First, estimate the size of your lawn to determine how much Tenacity herbicide you will use. You don’t want to under spray (which will lead to some weeds surviving) or overspray (which can damage your lawn).
  • Create your tenacity solution by diluting the herbicide with water. Follow the ratios provided in the packaging instructions strictly.
  • For better results, you can add a surfactant to help the solution stick better on crabgrass for more absorption. The surfactant is an excellent idea at the post-emergent stage. Any non-ionic surfactant will work well with Tenacity.
  • With the solution ready, you can spray your lawn or any other part of your property where you have crabgrass infestation.
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Once you have applied Tenacity, the weed killer will immediately start acting on the crabgrass. However, visible will take time about two to three weeks.

When should I apply for Tenacity?

crabgrass preventer
Photo: BanksPhotos

The best time to spray Tenacity will depend on whether you are using it as a pre-emergent or post-emergent herbicide.

When making a pre-emergent application, you must spray your lawn before the crabgrass germinates around fall or early spring before the rains begin.

For post-emergent application, you should spray the weed killer when the crabgrass is still young before it starts seeding.

How often should you apply Tenacity?

Tenacity is very effective in killing crabgrass and usually requires only one application. However, repeated applications might be necessary if there are any residual weeds.

If you have applied at the pre-emergent stage, you will not need to apply the herbicide again. However, if any weeds survive, you can allow them to germinate and use Tenacity again as a post-emergent herbicide.

If you have applied Tenacity at the post-emergent stage, results will be visible after two or three weeks. You can make a second application round to kill any residual crabgrass at this stage.

Does Tenacity kill your grass?

One of the significant concerns when spraying a lawn with a herbicide is whether you will harm your grass. Fortunately, those fears are unwarranted when it comes to Tenacity.

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The weed killer is selective and will not harm your grass. It is intended for crabgrass control and a range of other broadleaf weeds.

However, you might notice some of your grass turning white immediately after application, though this resolves after a few days.


Eliminating crabgrass from your lawn can be a tiresome task. If you don’t deal with it soon enough, it can disperse its seeds, increasing the infestation.

On top of that, it can resist several chemical herbicides, while other weed killers can be too much and kill your lawn grass.

However, Tenacity offers you a perfect solution for eliminating crabgrass. It is a pre-and post-emergent herbicide, meaning you can target the weed before and after germination.

It is also systematic and thus more lethal to the crabgrass. Lastly, it is selective, which allows you to eradicate crabgrass and other weeds without destroying your lawn.

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