Will Bleach Kill My Grass?

I spend a lot of time tending my garden so that my family and I can enjoy our backyard oasis in our downtime. One common annoyance in my garden beds is weeds – but more importantly, patches of grass that creep between the cracks in my concrete patio. Not all weed killers attack everyday grasses, but is it a good choice to use bleach since it kills everything? Well, that depends on a few things.

will bleach kill grass

Bleach is a multi-purpose chlorine-based chemical that pretty much kills anything with which it comes into contact. In small, diluted doses, bleach may not be harmful to plants; however, when undiluted, it will likely kill whatever living plant it touches. This is why it is so important to plan ahead when using bleach if you do not want to harm the yard you work so hard make beautiful.

Keep in mind that this short answer is informational but also a warning. To understand when it is appropriate to use bleach, you should consider how it works.


Why Will Bleach Kill My Grass?

During the Covid-19 pandemic, bleach was in high-demand because it was a perfect cleaning product to kill germs that other antiseptic sprays might not. The common bleach found in everyone’s laundry room is made up of between 5-6% sodium hypochlorite. This means that there is a ton of salt in bleach. In fact, the pH balance of sodium hypochlorite is about 11. To have plants grow, you’ll want healthy soil with a pH of between 6 and 7.

ph scale bleach

So, by adding bleach to the soil, you raise the pH to unrecommended levels. This highly basic soil will cause any plants to die off, including grasses, because the nutrients and bacteria that plants require are leached from the soil. Also, basic soil is higher in the nutrient molybdenum, which becomes toxic to plants in higher levels. When you bleach out the soil, you will not only kill the plants, but permanently affect the soil for future plants.

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How To Use Bleach in Your Garden

There are a few steps to using bleach if your purpose is to get rid of grass in an area, like the between pavers in walkways.

Check The Location

Make sure that the area you want to work on does not boarder a flowerbed. If it does, you’ll want to be extra careful that the bleach does not make contact with the flowerbed or the plants in it. If it is adjacent to a flowerbed or other plant life, you’ll want to follow additional steps to dilute the soil afterwards.

You will also want to be sure that the area you want to work on is not near drainage ditches or bodies of water. Bleach is poison to aquatic life. Trust me, it will not make you happy if your lovely fish go belly-up in your homemade pond. It will also kill the lotuses and lily pads.

Prepare Your Equipment

One to two cups of bleach will kill about a square foot of grass. If you are focusing your grass-killing to a patch, a spray bottle will work best. A nozzle that can be adjusted to make a small stream will work best for direct hits to root systems and plants that may be coming through cracks.

Be sure to wear old clothing before preparing your materials. Be sure to wear gloves to protect your hands. Have you ever gotten bleach on your skin? You’ve likely noticed that it is a bit slimy. This is not the bleach that feels that way. That sensation you feel is actually the oils and dead skin cells on the top layer of your skin breaking down from the chemicals. Not so charming, is it?

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Using Bleach

Now that you have prepared your materials and are dressed in safe clothing, it’s time to tackle that pesky grass. With spray bottle in hand, spritz bleach on the blades of grass that you want to kill. That’s it. Within two or three days, the grass will turn brown and die. This will have killed the grass all the way to the roots. Go back to the treated grass and pull it out, making sure to get the roots as well. You can use gardening tools for this, but you may find it easier to use a butter knife dedicated for gardening.

Rinse After Using Bleach

You’ll want a gallon of water for each cup of bleach you use during this gardening process. Use a hose to quickly saturate the surrounding ground. This allows the bleach to filter down to deeper levels of the soil, keeping it from raising the pH too quickly in the upper levels of soil where plants root.

Other Tips

  • One or two drops in a vase full of water can extend the life of your cut flowers. While this is helpful once the plants have been trimmed from the ground, you only want to use bleach if the flowers are out of the soil.
  • Another product that is often quite effective at killing plants and grass is vinegar. Simple white vinegar is a natural chemical that will not permanently harm the soil, and it will not cause as much havoc to the ecosystem or waters with which it comes into contact.
  • If you want to clean a deck or concrete slab with bleach, be sure to follow the instructions above to leach the bleach out of the soil as it trickles down through the soil layers. You can also lay down drop cloths along the border to suck up most of the bleach and water, though you’ll still want to dilute the surrounding area with water to protect from any possible leakage. You may also want to consider a more natural method for cleaning, such as a water, vinegar, and baking soda mixture.
  • Fisherman will tell you that putting bleach in the ground brings nightcrawlers to the surface quickly. However, contact with the bleach will kill the worms, so they should be rinsed in a large bucket of fresh water. Note that a lot of water will also bring worms to the surface, but it may not be as quick or as effective.
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