Baking Soda Weed Killer: Tips and Tricks for a Homemade Solution

Why Baking Soda?

We all love baking soda, also known as sodium bicarbonate. This white, crystalline powder is a naturally occurring substance with many uses around the house, from an environmentally-friendly cleaner and odor eater to a baking ingredient in the kitchen. It’s even traditionally used as an antacid.

Baking soda’s merits in the garden come down to a few facts:

• It’s effective,
• inexpensive,
• on hand as a pantry item,
• super easy to apply,
• all-natural,
• not a toxic chemical such as glyphosate, which is poison to our bodies, wildlife, soil organisms, and water.

That said, baking soda isn’t the type of weed killer that should be used excessively to blanket garden weeds. Let’s “dig in.”

How Baking Soda Kills Weeds 

Note the word sodium in the name. Baking soda is basically just a type of salt—but not the kind found next to the pepper.

What does salt do (chemically) when it comes into contact with weeds (or any plant)? 

• If the soil is high in salinity, it creates an imbalance that chemistry attempts to resolve by drawing water out of plant roots and back into the soil, heavily dehydrating the plant.
• If salts come into direct contact with leaves, they pull moisture from them in much the same way (a process called osmosis). If saline levels are too high, the plant (in this case, a weed) dies from dehydration.

It’s essential to recognize that baking soda has this effect on all plants—not just those weeds you’re trying to control. It’s not a selective type of weed controller (the way some herbicides are). It’s easy to overdo it, and it’s possible to injure the plants you’re trying to protect from weeds.

You can see the effects of salt at work in nature. For instance, the only plants that can grow around the Great Salt Lake in Utah have a specialized high salt tolerance.

Baking Soda Weed Killer Recipe

There are two main ways to use baking soda as a weed killer: wet or dry. Here’s the lowdown on both methods.

To use dry baking soda:

1. Dampen the leaves of your target weed with water.
2. Lightly sprinkle baking soda onto the wet leaves. With the water, the baking soda will easily stick to the leaves. Do this on a day with light wind so the baking soda won’t blow around where you don’t want it.

To use wet baking soda spray:

1. Combine baking soda and water and put the mixture in a spray bottle to spritz on weeds. The specific ratio of baking soda to water can vary widely, but a straightforward “1 cup baking soda to 1 gallon water” mixture is popular.
2. Spray directly on the weed. Be cautious to avoid contact with desirable plants.

How to Use (and Not Use) Baking Soda to Kill Weeds 

As a weedkiller, it’s best to use baking soda in small, diluted amounts and in a targeted way. For example, use on weeds that spring up solo on your patio or walkway and near your driveway. In these cases, other plants aren’t at risk from the side effects of the salts. 

It’s not the ideal solution for targeting weeds near your veggies or prized flowers—this is just asking for trouble. Even if you’re careful and the baking soda doesn’t physically touch your “good” plants, the salts left behind in the soil can add up over time, potentially severely damaging your soil, which is a challenge to undo.

On a side note, note that Epsom salt is not good for plants like tomatoes. This is a myth.

Other Natural Alternatives to Baking Soda Weed Killer

There are other natural, homemade herbicides that we use in the garden.

• Vinegar: Some gardeners love using vinegar as another natural ingredient in a mix with baking soda, but some gardeners also use vinegar alone. Spraying or dabbling vinegar on troublesome weeds can cause significant leaf damage, though its effects as an herbicide diminish rapidly over time. But the main downside to vinegar is that it is, after all, an acid. It seems friendly in the kitchen, but you wouldn’t want to put vinegar in a spray bottle as spraying it could potentially result in burns if it comes in contact with your eyes or skin. Always work safely, says the Utah State University Extension.
• Dish soap: If you make a baking soda/water spray, you can add a dab of dish soap to the mix, which will help the solution stick to the weeds’ leaves.
• Boiling water: It doesn’t get much simpler than this. Boiling water can be an effective option, but it works best on weeds that have popped up between pavers or in other isolated areas, according to the Colorado State University Extension.

Baking Soda Weed Killer: A Natural Option

Can you use baking soda as a natural weed killer? Yes, indeed. But just because something is “natural” and lives in your pantry doesn’t mean it’s 100 percent harmless. Heavy use of baking soda on weeds can put excess amounts of salt in your soil, so you’ll want to be careful with it. 

That said, baking soda does effectively kill weeds by dehydrating them severely, and baking soda is easy to obtain and inexpensive. It’s a quick solution for individual weeds causing trouble on brick walkways or in between pavers—the weeds may very well not return, and you’ll have eliminated them without the use of herbicides. 

Bottom line: Use common sense when using baking soda in the garden. It’s effective for a quick spray on patio weeds, but it shouldn’t be used in excess or near other prized plants.