Roundup VS Tenacity – Which is Better?

You have many options for weed killers. Two of the most popular brands are Roundup and Tenacity. But which of these should you use on your lawn? This article will compare them in terms of effectiveness, speed, and safety to help you make the best choice for weeding your lawn.

Roundup vS Tenacity – Which is Better?


The biggest criterion for what weed killer is better is effectiveness. If you have all the time in the world to make your lawn look good, which herbicide will do that more efficiently?

Let’s start with a big difference: Tenacity is a selective herbicide while Roundup is not. This means if you use Tenacity on your lawn, it will only harm the weeds. But if you use Roundup instead, it will kill other plants in the area, including your grass. There is such a thing as being too strong. Roundup is the plant equivalent of a nuclear bomb.

There are also some reports of Roundup not being as effective as it claims to be. These may be due to failed attempts at mixing the formula, or maybe they were bad batches. Regardless, it’s a knock against Roundup’s efficacy.

Roundup’s main ingredient, glyphosate, is so potent that it will kill your lawn if you use it there. You must be careful to use “Roundup for Lawns” if you wish to use Roundup on your lawn. Roundup for Lawns is worth another section.

This is not to say Tenacity is perfect. Tenacity often requires multiple applications to stick. However, it is useful in that it is both a pre-emergent and post-emergent—that is, it can be used both before and after the weeds have popped up on your lawn. Apply in spring or fall for the best results.

And when the lawn comes up, it sprouts weed free. Tenacity takes more patience, but the result is a beautiful, weed-free lawn. Since it kills over 46 species of weeds, including undesirable grasses such as bentgrass and crabgrass, you will have saved yourself a ton of time in the long run.

Winner: Tenacity. Do not blast your grass.


Speed is one area where Roundup has Tenacity beaten. When Roundup works, it can kill weeds in anywhere from 3–24 hours. If you need weeds gone from your sidewalk, patio, or driveway, Roundup may be the solution. Roundup for Lawns is equally effective on your lawn, but you’ll see why it isn’t quite Roundup.

Tenacity, however, can take up to a week to kill weeds. If you plan to remove those weeds weeks in advance, Tenacity is the better herbicide. But if you want things done quickly, Roundup is for you. Just be very careful where you aim.

Winner: Roundup. It is that fast.


Tenacity is one of the safest commercial weed killers out there. It is safe for pets and kids. The biggest risk when using Tenacity is rain; it is rainproof 1 hour after application but not recommended when rain is predicted. Even if it is safe for your pets and kids after it dries, it is still a chemical that should be handled with care.

But Roundup is definitely unsafe. Its main ingredient, glyphosate, is not only good at killing plants but is poisonous to many other things, too. Roundup must be disposed of at a hazardous waste facility—no exceptions. Dumping it down a drain or toilet could poison the local water supply. Yes, Tenacity also has warnings, but its effects are not as notorious.

If you use Roundup on your driveway, you probably will not care about safety. But if you use it on your lawn or around vegetables, there are reasons for it to be non-toxic. One Californian successfully sued Roundup for causing his cancer, so you may want to think before buying a bottle. And never dump it down the toilet.

Winner: Tenacity. Causing cancer is a major health risk (see also: asbestos). 


Tenacity has one major drawback: price. No matter how much Tenacity you buy, it will be expensive. Expect to pay at least 60 dollars for a container of Tenacity. You may be able to save a few bucks by going for an off-brand counterpart. Look for “mesotrione.”

Roundup is cheap by comparison. Professional-grade formulas in large quantities cost hundreds of dollars, but most packages of Roundup cost 22 to 50 dollars. You can also get off-brand glyphosate, but there is not much reason to.

Winner: Roundup. It might burn your lawn, but not your wallet. 

What About Roundup for Lawns?

But we must now consider a third contender: Roundup for Lawns. This is not technically Roundup because it lacks glyphosate, the ingredient that kills every plant in the area. The active ingredient in Roundup for Lawns is different. There might be a “Ship of Theseus” somewhere, but really, it’s just clever branding.

This article started discussing the standard formula of Roundup because people may already have Roundup for weeding their sidewalks, patios, or driveways—areas in which destroying other plants in the vicinity barely matters. But eliminating all plants does matter when you spray on a lawn. Tenacity is safer for your lawn, but Roundup is faster and cheaper.

If you take everything good about Roundup and Tenacity, then fuse them with the power of science, you get Roundup for Lawns. There are still some warnings on the label; please read them carefully before putting Roundup for Lawns on your grass. Roundup for Lawns has not been tested for toxicity as much as Roundup or Tenacity. Something that looks too good to be true often is, and we don’t really know what the “catch” to Roundup for Lawns is. It has a lot of different things in it.


If you must pick between Roundup and Tenacity, and money is no object, go for Tenacity’s long-term, safe formula. The real winner might be Roundup for Lawns. Comparing Roundup and Tenacity is like comparing a spoon and a fork; Roundup and Tenacity are both weed killers with slightly different purposes. One is designed for lawns; the other is better on the pavement. Roundup for Lawns is a spork that tries to get the best features of both tools. If you have infinite funds and patience, Tenacity is better overall, but there’s no shame in using the spork.

Also Read

Does Tenacity Kill Crabgrass (How to use Tenacity to Kill Crabgrass)

Tenacity vs. Prodiamine

Meso 4SC V.S Tenacity

Does Roundup Kill Grass?


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