9 Ways to Use Cream of Tartar in the Garden as a Natural Pesticide, Weed Killer, and More

Cream of tartar is a white, powdery ingredient also known as potassium bitartrate, which is often used in baking to stabilize egg whites, prevent sugar from crystallizing, and aid in leavening. But did you know this marvel can also be utilized in the garden? From keeping out garden pests like aphids to removing unwanted stains and smudges on outdoor furniture, cream of tartar can be used in a myriad of ways. Here, we share tips and tricks from gardening experts who use cream of tartar in their own gardens and green spaces.

Keep Out Aphids

Sprinkle cream of tartar over your soil or on plant foliage to keep out aphids, sap-sucking insects that can damage your plants. You can also use cream of tartar to make a spray by mixing 1 tablespoon of cream of tartar, a few drops of dish soap, and 1 quart of water. "This solution should then be added to a spray bottle and sprayed onto plants with aphids," says Lucie Bradley, a gardening and greenhouse expert at Easy Garden Irrigation. Spray it on the underside of leaves where these insects like to hide. This mix disrupts aphids' ability to breathe, feed, or move around, Bradley says. 

Prevent Slugs and Snails

Neither slugs nor snails like the feeling of cream of tartar. Hence, you can sprinkle the baking ingredient around your plants to create a barrier that keeps snails and slugs out of your garden. "It’s a safe, natural way to deter these unwanted visitors," says Bradley. And if the cream of tartar is washed away by rain or blown away by the wind, sprinkle more to replenish the barrier.

Deter Ants

Ants don’t like cream of tartar either. "A pinch of cream of tartar sprinkled in a fine line makes a quick ant barricade around pots or seed flats," says Tammy Sons, a master gardener and founder of TN Nursery. The salty-acid crystals irritate the bugs' feet, so the ant invasion into your green spaces usually stops within an hour. "However, the cream of tartar does wash away in rain or heavy watering, so you’ll need to re-dust after every soak," she says. Unfortunately, cream of tartar won’t disrupt underground ants' nests.

Don't Miss

Don’t Buy Ladybugs! Here’s How to Attract Them Naturally to Eliminate Garden Pests

How Gardening Experts Use Cinnamon to Deter Pests, Boost Plant Growth, Improve Pruning, and More

Remove Rust from Garden Tools

As an acidic compound, potassium bitartrate can break down and help prevent rust on gardening tools. For the best results, Bradley recommends making the cream of tartar into a paste by mixing it with white vinegar or lemon juice. "Or for a very strong solution, make a mix of cream of tartar, baking soda, and hydrogen peroxide," she says. Apply the mix to your tools and let it sit for five minutes or longer to loosen the rust. Rinse the mix away and dry your tools thoroughly.

Kill Weeds

Believe it or not, cream of tartar is a natural weed killer. "When mixed with water, it can help control unwanted growth," says Johannes Hock, home gardener and president of Artificial Grass Pros. Combine 1 tablespoon of cream of tartar with 1 gallon of water, then spray the weeds in your garden. "It is a nontoxic method of keeping your yard neat," he says. 

Clean Wooden Garden Furniture

Create a cleaning paste to remove stains from wooden outdoor furniture. To do this, mix cream of tartar with water (or vinegar for more stubborn stains), says Bradley. Cover the stain with the paste and let it sit for 15 to 20 minutes. Rub the paste in circular motions, then rinse with warm water. "It’s important when cleaning wooden furniture that you test the cleaning solution in an inconspicuous place just in case it does negatively affect the appearance," she warns.

Combat Powdery Mildew

Cream of tartar can also solve your powdery mildew problem. All you have to do is dissolve 1/2 a teaspoon in a quart of warm water, add a drop of dish soap, and mist powdery mildew-prone leaves, says Sons. "The acidic solution changes leaf pH just enough to discourage fungal spores. I’ve seen good results on cucumbers and zinnias," she says. However, it must be applied every few days and can burn tender foliage if sprayed at high noon, she warns.

Remove Grime From Greenhouse Glass

Use cream of tartar and water for a natural, plant-safe way to clean greenhouse glass. "Make a paste by adding water to some cream of tartar and rub this onto limescale and stubborn marks on the glass," says Bradley. The slightly acidic but gently abrasive powder will dissolve any mineral deposits without scratching the surface of the glass. Rinse lingering residue from the greenhouse glass after cleaning.

Change Your Soil’s pH Balance

You can use cream of tartar to change the pH level of your soil for plants that need acidic soil, like blueberries or azaleas, says Sons. Stir 1 tablespoon into a gallon of water and drench the soil. "The potassium bitartrate nudges the pH downward without the harshness of sulfur," she says. However, she recommends testing soil first and going slow because repeated doses can over-acidify and bump up potassium levels more than some plants prefer.