7 Genius Ways to Use Cornstarch in Your Garden for Healthier, Pest-Free Plants

Cornstarch may not be the first thing that comes to mind when you think of garden tools. But its versatility makes it a valuable addition to your gardening arsenal, and sometimes the simplest solutions are the most effective.

Even though cornstarch is normally known as a pantry staple, it works as a surprising solution in the garden, too. From deterring pests to treating plant diseases and even preserving seeds, cornstarch offers a variety of benefits for eco-conscious gardeners.

Below, we share seven genius ways to use cornstarch in your garden, plus a few tips to consider before getting started.

Deter Ants

Cornstarch is a natural deterrent for ants. Simply sprinkle a small amount around any ant mounds, garden beds, or pest entryways.

“I sprinkle a little around ant mounds or other pest entryways to deter them, as well as some other soft-bodied insects because they can’t digest it,” Tammy Sons, CEO and Founder of TN Nursery suggests.

The fine powder clogs their digestive systems and prevents them from eating plants. This makes cornstarch a great non-toxic barrier.

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Combat Mildew and Fungal Issues

Fungal diseases like powdery mildew can wreak havoc on your plants. To help with this, you can make a DIY spray using one tablespoon of cornstarch with one quart of water. You can also add a teaspoon of baking soda to the solution for its alkaline properties. Spray this mixture on any affected foliage.

“I have used this mixture (with baking soda) and sprayed it on foliage with fungal issues,” Sons says.

Sons also shared that mixing cornstarch and water has helped with powdery mildew in her experience.

Thicken Natural Insect Sprays

If you already make your own natural insect sprays using essential oils or garlic, cornstarch can help improve their effectiveness by thickening the solution.

A thicker solution means the spray will cling to the leaves and stems better, increasing the duration the spray stays in contact with any pests.

Preserve Bulbs and Seeds

“(Cornstarch) is also a natural drying agent for storing flower bulbs or seeds to help avoid mold,” Sons says.

Since cornstarch absorbs moisture, it naturally helps prevent mold. When storing flower bulbs or seeds, dust them lightly with cornstarch before placing them in a paper bag or other breathable container. This helps keep them dry and viable for the next planting season.

Soothe Irritated Skin After Gardening

While not directly for use in the garden, cornstarch can be a gardener’s best friend after a long day working in the garden.

If you’ve encountered itchy plant or insect bites, a cornstarch paste (mixed with a little water) can help soothe irritated skin. Apply it to the affected area, let it dry, and rinse off gently with warm water.

Prevent Slippery Surfaces

If you often deal with slippery garden pathways and stepping stones due to algae or moisture, cornstarch is a quick fix. Sprinkling a bit of cornstarch on these surfaces can help absorb excess moisture and reduce slipperiness.

Loosen Clay Soil

Clay-heavy soil can be dense and compacted, making it hard for seeds to sprout. Mix a small amount of cornstarch into the soil to help loosen it slightly and retain moisture more evenly. This will give seeds a better start.

Things to Consider Before Using Cornstarch in the Garden

While cornstarch is a helpful tool, it’s not a cure-all.

“Just a word of caution: use (cornstarch) sparingly because it can clump with moisture and turn into a sticky, starchy goo in large amounts,” Sons suggests.

Overuse can be counterproductive and lead to mold or attract unwanted pests if it becomes too wet.

Always test any cornstarch-based solution on a small area of your plant before applying it throughout the garden.

“It is not a magic bullet, but it is worth a try as a non-toxic, organic tool in your gardening toolbox,” Sons says. “As I always suggest when using any home remedy: test, test, test on a small portion before drenching your whole garden, as different plants, just like people, have their likes and dislikes.”