What Does Bleach Do To Grass? Will It Kill Weeds?

If you have particularly stubborn weeds in your yard, you’ve probably tried several solutions to get them to die off permanently. 

Perhaps you’ve heard of using household bleach as a powerful herbicide. 

But is bleach effective? 

And what will it do to the grass and other nearby plants on your lawn?

Bleach is a very powerful yet non-selective herbicide, meaning it will permanently kill weeds and most other plants in its path. It works by raising the pH level of the soil it is applied to over the course of a few days.

Keep reading to learn more about this unique – if a bit extreme – method of killing weeds and unwanted grass. 

We’ll also cover when and where it should be used for best results, as well as some safety precautions to keep in mind.

what does bleach do to grass

What Does Bleach Do To Grass?

Chlorine bleach has a very high pH level of around 11, while most normal soil used for grass and other plants usually has a pH level of 3.5 to 10. 

This means when bleach is applied to soil, it will raise its pH level drastically, killing any weeds and ensuring nothing will be able to grow wherever it is applied. 

This includes pesky weeds like dandelions, but it will also kill off grasses and other plants you likely want to keep in your yard, such as flowers and crops.

Additionally, bleach contains high amounts of chlorine. 

Interestingly, chlorine is a micronutrient naturally present in soil and a key facilitator of plant growth. 

However, too much of it will cause chlorine toxicity and kill plants, at first turning their leaves brown and eventually causing them to shrivel up and die off completely.

As you might imagine, bleach contains far too much chlorine to encourage plant growth, meaning it causes chlorine toxicity in most plants very quickly. 

This is great if you’re using it to kill isolated weeds popping up in the cracks in your driveway, but you should think twice before applying it recklessly to any weeds near plants you want to keep healthy!

Speaking of weeds, check out these ways to fix gravel driveways overgrown with grass.

Will Bleach Kill Weeds Permanently?

Yes, bleach will kill any weeds it is applied to permanently. 

If applied in a large enough amount to saturate the soil underneath, bleach will soak into it and make it uninhabitable for any weeds to grow back.

Unfortunately, chlorine bleach will also prevent anything else from growing back, such as grass, flowers, or any other plants you were potentially hoping to replace the invasive, annoying weeds with. 

As we touched on earlier, its high amounts of chlorine and extremely basic pH level are highly toxic to your soil, as well as most plants and animals unfortunate enough to come in contact with it. 

In most cases, bleach will prevent any plants from growing back for several months or even longer.

If you want to use bleach to kill weeds in your yard, it’s best to only use it in isolated areas where you don’t plan on planting anything new, such as on the cracks in your driveway, for example. 

Otherwise, you risk damaging the soil to the point that you won’t be able to plant anything new in the area where the bleach was applied for a very, very long time.

Additionally, bleach is highly toxic to animals if ingested or if it gets on their skin, so if you don’t want to potentially harm any critters hanging out in your yard, be very selective with where you apply it.

If you want some alternative options read our post on options to kill weeds permanently.

How To Kill Weeds With Bleach

Since bleach is such a powerful herbicide, killing weeds with it is a fast and simple process. Simply pour it into a spray bottle (optionally with a bit of water to dilute it slightly) and carefully spray it directly onto any weeds or other plants you’re getting rid of. 

Alternatively, you have the option of simply pouring the bleach (or water and bleach mixture) directly onto the weeds you intend to eradicate. 

This method is a lot harder to control, though, so only pour bleach on weeds in isolated areas and small amounts. 

Keep in mind, though, you’ll need to take some safety precautions beforehand for best results, as bleach isn’t intended to be used as an herbicide in the first place.

Safety Precautions When Using Bleach As An Herbicide

If you’re planning on using bleach to kill off the weeds in your yard, you’ll need to be very cautious to avoid harming any nearby animal life or children, as well as any plants you want to keep safe. 

In addition, you’ll have to take some precautions to avoid irritating your own eyes or skin in the process.

First, be sure to wear gloves and protective eye gear whenever using bleach as an herbicide. 

If your eyes or skin come in contact with bleach, you’re going to be in a lot of pain.

Next, use a small amount of bleach or bleach and water solution on a “test area” patch of grass first to test its efficacy. 

This will give you a good idea of how it will affect larger areas of weeds or other plants it is applied to.

Do not spray or apply the bleach onto plants or grass you want to keep, and avoid using it on a rainy or windy day, so it doesn’t immediately run off into other areas of your yard or seep into surrounding ground water. 

Keep any kids or pets away from the area you’ve applied the bleach for a day or two or until the area is fully dry.

Finally, don’t mix the bleach with any other chemicals. 

It will work fine as a herbicide on its own, and mixing it with other chemicals will often create more hazardous byproducts.

How Long Does It Take Bleach To Kill Weeds?

After you’ve applied the bleach to the weeds in your yard, it will take anywhere from one to three days or so for it to fully kill them off. 

You will likely notice leaves beginning to turn yellow or brown within minutes or even seconds of applying the bleach. 

This is a good sign the excess chlorine in the bleach is causing chlorine toxicity in the weeds and affecting their pH level, meaning they will die off completely soon. 

The high pH and high amount of chlorine are also what make bleach such an effective weed killer.

Remember, any area you’ve applied the bleach to will be uninhabitable for any plants for anywhere from a few weeks to even several months.

The length depends on how much you’ve used and how well it has saturated the soil underneath.

How To Fix Bleach-Contaminated Soil And Plants

If you’ve accidentally applied bleach to plants you wanted to keep and aren’t sure what to do, don’t panic. 

In some cases, you’ll be able to reverse its effects if you act quickly.

Immediately rinse the affected plants with clean, fresh water, ideally with a garden hose or sprayer. 

This will dilute the excess bleach and at least remove it from the surface of the plants so their leaves won’t immediately turn brown. 

If possible, remove the plants entirely and replant them somewhere far away from where you applied the bleach, as it soaks into the soil and affects its pH fairly quickly. 

Use new garden soil if you are able and water the plants often to eliminate any traces of leftover bleach. 

Many expert gardeners recommend using a soil pH test kit, like this one, to more accurately assess the damage.

Unfortunately, if the damage to your plants is too extensive, you won’t be able to salvage them. 

If you notice the damage quickly and work fast to move the plants and rinse them off, though, they will have a chance of survival. 

In the future, be more careful and selective about how you apply the bleach to avoid any further mishaps!