Tenacity Killed My Grass – Why & What To Do

Tenacity is a popular herbicide used by gardeners for years to control weed growth in their gardens. So if you applied it to your lawn, you’re probably frustrated to find that it killed more than just your weeds – it killed your grass! Now, rather than the luscious green weed-free grass that you imagined, you’re left with a lawn strewn with unsightly and unhealthy yellow and brown patches. But why did this happen and what can you do (if anything). Well, here is all you need to know.

So why did Tenacity kill my grass? Tenacity may have killed your grass due to over-application, the condition of your lawn when it was applied, or the weather conditions at the time of application. 

Fortunately, these undesirable side effects can be explained and even avoided.

Below, I’ve shared everything you need to know, alongside tips on how best to revive your grass too. 

Keep reading for all the important details! 

Why Did Tenacity Kill Your Grass?

Heavy Use 

As with any fertilizer or herbicide, it’s crucial that you adhere to the recommended proportions and frequency of application when you use it.

It’s much too easy to be a little heavy-handed while you dispense it, particularly when you’re dealing with an abundance of weeds, so you’ll need to be disciplined.

Reason being, Tenacity contains a high level of nutrients such as nitrogen, which admittedly enable the product to do its job well but will also destroy your lawn if they’re present in large quantities.

As a result, your lawn will struggle to absorb the excess nutrients, causing it to suffer from herbicide burn, which is essentially the same condition as fertilizer burn.

Thus, your lawn may indeed be weed-free, but it will also be yellow, brown, patchy, and dry. 

Prior Lawn Health 

Despite the fact that Tenacity is a weed removal solution, it’s important that your lawn is in good health prior to its application.

If your grass is already struggling for whatever reason and is too weak, thin, brittle, or even dead, it won’t be able to hack the strength of the Tenacity that comes into contact with it, despite its selective properties.

As a result, the Tenacity will remain on top of it rather than being absorbed below the surface, in turn causing your grass to burn and your weeds to remain. 

Time of Application 

Finally, when it comes to applying herbicides, there’s a right time to do so.

Tenacity is at its most effective when used in pretty much any temperature aside from those of high heat.

So, be sure to only apply it when the outside temperature is below 26°C, and it’s best to do so when your lawn is dry too.

For this reason, it makes sense to refrain from its application both during the Summer and Winter months and to opt for the calmer days that make up Spring and Autumn time instead. 

It’s also important that you apply it on a dry day.

Once applied, Tenacity takes a couple of hours to dry, and if it rains during this time, its effectiveness will be compromised. 

Can Grass Grow Back Once Killed by Tenacity?

Grass is resilient, and even if Tenacity damages it, it’s very much possible to nurture your grass back to good health. 

There are various steps for you to take to do so, but fortunately, they’re all relatively uncomplicated to action.

However, patience is a must. You’ll need to accept the fact that your grass won’t be restored to its former glory overnight.

Rather, it will be a process and one that could take weeks or even months. 

Persevere, and your efforts will surely pay off! 

How to Restore Grass Killed by Tenacity

Follow the below tips, and you’ll revive your grass in no time! 

Soil Testing 

First and foremost, it’s worth checking in on your soil.

By becoming familiar with what its nutrient and pH levels are, you’ll be able to precisely decipher what caused your grass to die and will be in a better position to take the necessary steps to revive your lawn and, more generally, care for your soil moving forward. 


Aerating your lawn reduces its compactness by punching holes into it to allow for improved draining and, thus, the improved uptake of nutrients, water, and air.

After all, these three elements can only have a truly positive impact when they can actually reach the soil.

Thus, aeration promotes healthy growth, and within a few weeks of the process, you’ll begin to notice not just the gradual revival of the dead patches of grass but the emergency of healthy new grass too. 

Watering and Fertiliser 

Watering your grass and applying fertilizer are two core contributors to the growth of luscious grass.

Water will ensure that your grass doesn’t become too dry, and it is also necessary for the process of photosynthesis through which the lawn essentially makes its own food, in turn enabling it to survive and go on to thrive!

Fertilizer, on the other hand, provides your lawn with a boost of nutrients, allowing it to grow to the best of its ability.

If your grass is dead, both of these aspects of its care become even more important than they usually are.

And, of course, they’re most effective when applied to a well-aerated lawn rather than one without room for them to travel down to the roots. 


Overseeding is another method you might want to consider.

It’s the process of planting new seeds over your existing grass and giving them time to germinate and grow.

Before you know it, the new healthy grass, albeit it young, will take over your lawn, and the yellow patches will gradually diminish until they are no more! 

Healthy Lawn Maintenance 

Above all, establishing a regular lawn care routine is key!

This means watering and fertilizing not just when disaster strikes but on a continual basis, as well as mowing your lawn regularly to encourage healthy growth and overall great-looking turf!

You’ll also need to continue striving to remove weeds from your lawn.

However, if your grass is still in a state of ill health, for the time being, I recommend pulling the weeds out by hand rather than using a herbicide. 

How To Use Tenacity More Effectively In The Future

The best thing about Tenacity is its selective nature.

This means that, in theory, it shouldn’t harm your grass.

Hence, rest assured that if you use it properly, your lawn will stay in great health and be sans weeds before you know it! 

To stay on track, keep the following in mind: 

Use Sparingly

First, refrain from over-applying Tenacity.

As explained above, too much of its nutrients will harm and burn your lawn, doing much more harm than good. 

Apply On Dry Days

Second, apply Tenacity on dry days when it will have sufficient time upon its application to dry and thus to be absorbed and operate as effectively as it can.

It would be a shame to go to the effort of applying it, only to have wet weather wash it out and deem it redundant.

On the same note, avoid applying it in temperatures over 26°C. Tenacity doesn’t fare well in the heat and, once again, risks burning your lawn. 

Implement A Consistent Lawn Care Routine

Finally, to avoid the ill effects of the product, as well as other lawn-related issues, it’s best to stick to a consistent lawn care routine consisting of regular maintenance, such as watering and mowing.

Your grass needs your attention all year round, and if you’re regularly exposed to it, you’ll be able to spot irregularities and issues when they initially crop up rather than when they’ve spiraled! 

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