Yes, Baking Soda Kills Weeds — But Follow This Expert-Approved Advice First

published Jun 26, 2024
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There are a lot of rewarding parts of gardening, like seeing your plants grow and transform over time and harvesting a bounty of veggies or flowers, for starters. But as a professional horticulturist and onetime nursery owner with a couple decades of experience under my belt, I know there are plenty of frustrating parts, too. One of the biggest annoyances, whether you have a large yard or a small patio garden, is dealing with weeds. The internet is full of ideas for how to get rid of them without using herbicides, and one of the more common suggestions is to use baking soda. But does baking soda kill weeds?

Your knee-jerk reaction might be that this “natural” weed killer (and cleaning favorite) is a better choice for your yard than store-bought herbicides, but that’s not necessarily true. While considering the question of whether baking soda kills weeds, you should also be asking another question: Will baking soda harm my other plants, too? Here’s what you should know.

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Does Baking Soda Kill Weeds?

The short answer is that baking soda may kill some weeds.

That’s because baking soda (chemical name: sodium bicarbonate) is a salt, meaning that when it’s sprinkled on leaves — or sprayed on as a water/baking soda mixture — it dehydrates plants, which eventually kills them. (Before they die, you’ll see effects like “burned” leaves, which turn brown at their edges.)

The catch, though, is that baking soda isn’t formulated to distinguish between weeds and plants you want to keep, as a store-bought “selective herbicide” would be. Since baking soda is nonselective, it will affect all plants in the area where it’s applied — that means weeds and the desirable plants around them.

Baking soda isn’t registered as an herbicide, so it doesn’t come with label directions for the amount of application as well as the frequency of application. That means you’ll be left to do some guesswork, which could be right on target to kill weeds effectively — or could be totally off base. 

The effectiveness of baking soda as a weed killer comes down not just to how much and how often you apply, but also what kinds of weeds you’re trying to kill. Some weeds are more shallow-rooted, which means that baking soda doesn’t have to penetrate very deeply to affect those plants.

But other weeds have taproots, bulbs, or tubers, all of which run deeper and stronger. For those, baking soda might not actually do the trick. While the above-ground growth might look dead, those weeds could keep resprouting from their resilient underground structures.

Where Is the Best Place to Use Baking Soda to Kill Weeds?

There’s one place that baking soda is a great option for killing weeds: when targeting unwanted plants that pop up on patios or driveways.

Since you’re not trying to selectively target some plants and not others in those locations — and are instead trying to wipe out everything — baking soda can be a good option to try if you already have the kitchen staple around.

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How Can You Use Baking Soda to Kill Weeds?

You can use baking soda to kill weeds in one of two ways: dry or wet. In either method, make sure to do this on a sunny day; rain will only wash away the baking soda, making it useless. You’ll likely have to repeat the process at least a couple of times.

Dry Baking Soda Weed Killer

Dampen the weeds you want to eliminate, then sprinkle baking soda on the leaves (the water will help that baking soda stick). Use about 1 teaspoon of baking soda per weed.

Baking Soda Solution Weed Killer

Mix a solution of baking soda and water — about 10 tablespoons of baking soda per gallon of water — then add to a spray bottle. Thoroughly spray the weeds you want to eliminate.

Credit: Dabney Frake

Are there other household products you can use to kill weeds?

If you decide to ditch the baking soda, and you’re considering other products or methods to use for killing weeds, your internet search might yield you suggestions of vinegar, salt, alcohol, bleach, dish soap, boiling water, and even a propane torch. Here’s how they measure up.

Salt, Dish Soap, and Boiling Water

Salt, dish soap, and boiling water are all nonselective ways to eliminate weeds, just like baking soda. That means they’ll kill everything around them, not just the weeds you’re targeting. Applying these in an area like a patio or driveway, where you don’t want any plants, is the best use case.

Vinegar

Household vinegar is simply not strong enough to do much of anything in the garden, so if you want to try vinegar as a weed killer you’ll need to reach for horticultural-grade vinegar (aka herbicidal vinegar). It contains less water than household vinegar, so its acetic acid content is significantly higher (10% to 20% as compared to just 5% in household vinegar).

Bleach

Bleach is not the best pick for one major reason. While it might kill weeds (and everything else in its path!) it will also brighten surrounding concrete. Unless you use it over your entire driveway or patio, you’ll end up with a patchy look.

Propane Torch

Called “flame weeding,” the use of a propane torch to kill weeds can be effective. It also comes with lots of cautions: Definitely do not do this on a windy day, and make sure to wear appropriate safety gear!

The best use of flame weeding is when you want to kill weeds in cracks of your driveway, sidewalk, and patio.

Your goal is not actually to set the weeds on fire, but to hit them with the intense heat from a torch so that their cell walls shatter and the water and cell sap boil, causing the weeds to wilt and die.

Should You Take Any Precautions When Using Baking Soda to Kill Weeds?

Even though baking soda is a household ingredient, that doesn’t mean you shouldn’t be careful when applying it. Contact with skin or eyes can cause irritation, and baking soda is harmful if inhaled as it can irritate your respiratory tract.

When applying, wear gloves; safety glasses and a mask are also smart steps, especially if you’re applying it on a windy day.

What about a nonchemical way to kill weeds?

If you want to remove all weeds and plants in a designated area — because you’re about to plant something new, you want to create a plant-free walking path or patio, or you’re getting ready to install a raised garden bed — solarization is an easy and effective option.

Solarization involves covering an area with a tarp to trap heat, killing everything beneath. While it’s effective, it’s not fast: This method typically takes weeks, not days.

The process is simple. First, outline the area you want to clear. Then fasten a plastic sheet or tarp over that area so it’s securely staked in the ground. After that, it’s a waiting game! Remove the tarp after about four weeks in summer or four to eight weeks in cooler months (you can pull up a corner to check progress over time). Everything beneath the tarp will be dead, so you can begin your yard or garden project from scratch.