8 Ways to Use Cornstarch to Create a Better Garden

Whether you’re growing a backyard garden for the first time or a seasoned horticulturist, anyone can benefit from some DIY hacks to take their home garden to the next level.

Cornstarch has become a popular base for beauty and household DIYs over the past couple of years, but did you know it can also be extremely useful in your home garden? Check out these tips to learn more about the many amazing uses of cornstarch.

What is Cornstarch?

Cornstarch is a staple ingredient in many people’s pantries. It’s typically used to produce light, fluffy baked goods or as a thickening agent in gravies, soups, and sauces. While flour can often substituted for cornstarch in recipes, it won’t work as an alternative in most DIYs. The reason cornstarch works so well for household and gardening tricks is that it is pure starch, whereas flour is only about 50% starch!

Cornstarch is a starch derived from the endosperm of corn kernels. When corn is soaked in hot water for at least 30 hours, it begins to ferment, and the germ of the kernel becomes separated from the endosperm. The germ is processed to create corn germ oil, and the endosperm gets milled then washed to obtain its starch. The final product is a fine, white powder with almost no taste.

Cornstarch Uses for Gardening

I’ve gone ahead and listed below 8 different ways to use corn starch in your garden. Now, I won’t try to pretend that corn starch is some miracle product or anything, but it’s certainly worth experimenting with as it’s extremely affordable.

So without further ado, let’s delve straight into these 8 surprising ways to use cornstarch in your garden.

1. Pest Control

Worms in your garden soil eat organic matter and excrete nutrient-rich nitrous, phosphorous, and potassium, which naturally fertilize the soil and help plants grow. While this is obviously beneficial, they can also act as pests.

If they climb the plants that you’ve worked so hard to cultivate, they may feed on the fruits, vegetables, and leaves of your garden. You can sprinkle cornstarch on the leaves of your plants to repel pests from landing and consuming your plants. The fine dust suffocates worms and makes it harder for small insects to walk on a leaf’s surface.

The Agriculture Research Service in Indiana is also investigating the effectiveness of corn starch and essential oil slurries for pest control. Garlic essential oil has been shown to repel mosquitos, snails, and slugs and even kill insect larvae. Consider creating a slurry of corn starch, water, and garlic essential oil to spray at the base of your plants to prevent gatherings of pests.

Cornstarch also works as an adequate method for trapping ants. Like worms, ants help support a healthy ecosystem, but they can also prove themselves to be harmful as well. Ants can protect and encourage aphids, a common garden pest, as they feed on aphid honeydew. Cornstarch cannot directly kill ants, but it does create a physical trap for them. Sprinkle cornstarch where ants gather and after 24 hours simply spray the cornstarch lightly with just enough water to form a paste. When it dries, it forms a cement-like material that traps the ants until they pass.

2. Reduce Water Usage

Corn starch works as a thickening agent in cooking by absorbing water into each individual starch particle. For this same reason, it works great as a soil additive to improve water retention. By adding corn starch to the soil of container plants, your garden will need less frequent waterings.

Not only does this mean less work for you in maintaining your garden, but it’s also better for the environment! Clean water requires a lot of energy, time, and money to filter so that it is potable. The filtration process uses non-renewable fossil fuels and releases carbon dioxide into the atmosphere, contributing to global climate change.

When adding corn starch to your garden bed to improve water retention, try using two tablespoons of cornstarch per gallon of soil. You can also add mulch or water-retaining granules mixed with compost to further the benefits.

3. Improve Soil Structure

A soil amendment refers to any additive to a soil that is used to improve the soil’s physical properties. These physical properties include water retention, water infiltration, structure, aeration, permeability, and drainage. Soil amendments are primarily used to provide a more nurturing environment for plant roots.

To properly integrate an amendment to your garden bed, you must make sure the soil amendment is thoroughly mixed into the soil. If the amendment is simply buried or sprinkled across the top of the garden bed, its effectiveness in improving soil structure is reduced, and it can even impede proper root growth.

Soil amendments such as corn starch can improve the soil structure and boost root growth. In a study by the North Carolina Agricultural and Technical State University, corn starch was among twelve organic materials that were tested for effectiveness as a soil amendment.

Corn starch leached the highest amount of dissolved organic carbon from the soil. Although dissolved organic carbon is important to ecosystem health, too high a level of DOC can release pollutants into its environment and contribute to acidity levels too high for healthy plant growth.

4. Control Nitrogen Levels

While nitrogen is considered one of the primary nutrients vital for plant growth, too much of it can be a bad thing. If too much nitrogen accumulates in your garden’s soil, your fast-growing plants may surpass your slow-growing ones and overcrowd them, leaving them no room for growth. Excess nitrogen buildup caused by fertilizers used in in-ground garden beds can also contaminate runoff and lead to harmful algal blooms in fresh and saltwater bodies near you.

Corn starch can be used as a means to control nitrogen levels in your garden’s soil. A 2019 study by NC State University tested the effectiveness of using corn starch to slow fertilizer distribution. Researched coated granular urea, a popular garden fertilizer, in a corn starch slurry and found that the nitrogen in the fertilizer was released into the soil slower than in uncoated fertilizer.

If you use a granular fertilizer in your home garden, try coating it in a corn starch slurry before introducing it to your soil for a similar effect.

5. Treat mildew growth

Almost no plant is insusceptible to powdery mildew growth under the right conditions. If you grow flowers like lilacs and zinnias or vegetables such as squash and cucumbers, your home garden is especially at risk. Powdery mildew is a fungal disease in plants that thrives in environments with high humidity at night, low humidity during the day, and mild temperatures between 70-80 degrees Fahrenheit. It is most often rampant in the spring and fall.

Although powdery mildew is not typically deadly, it does cause stress to your plants. The powdery, white film it forms on plant leaves blocks sunlight from reaching the chloroplasts and makes it hard for plants to photosynthesize. It can also rob important nutrients from the environment, leaving your plant weakened and more prone to other diseases.

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Corn starch is a great way to treat powdery mildew growth in your garden. Corn starch alone can’t treat your powdery mildew problem, but when combined with soap and water it proves to be an effective treatment. Try combining one tablespoon of cornstarch, one-half teaspoon of liquid soap, and one gallon of water then adding your solution to a spray bottle. Spraying the leaves and stems of your plants with this solution once a day should combat powdery mildew growth and prevent further outbreaks of the fungus in the future.

6. Grow seeds faster

Like all living organisms, plants need warmth to grow. Each species has an optimum temperature range, but cold weather will slow seed germination and plant growth no matter what kind of plant you’re looking to grow.

While it is not (yet) scientifically proven, many swear by coating their seeds in a paste made of corn starch and water to encourage faster germination and plant growth. It is believed that the seeds sprout more quickly because the cornstarch solution keeps them warm.

Pregermination in cornstarch for your seeds is another tactic to help them grow sooner. To try this, add a tablespoon of cornstarch to a cup of water and simmer until the solution thickens. Pour your solution onto a flat tray, such as a sheet pan, then sprinkle your seeds on top of it and cover the tray with plastic wrap, leaving a few holes for air circulation. As soon as you see roots emerge, plant the germinated seeds into your garden bed for best results.

7. Soothe a sunburn

Everyone has made the mistake before of spending hours in the sun without SPF protection. The last thing you want after spending hours perfecting your garden is to agonize over irritated skin. Luckily, cornstarch is a tried and true method for treating skin irritation. The pure starch powder is rich in antibacterial and anti-inflammatory properties.

To ease the pain of your sunburn, try mixing a paste of cornstarch and cold water together and applying a thin layer to the afflicted area. If you are a fan of baths, try mixing a few tablespoons of cornstarch into a lukewarm bath for a similar effect.

If friction from your clothes is worsening the irritation of your sunburn, try dusting your skin with dry corn starch. While it may be messy, it can reduce the chafing of your skin against clothes, bed sheets, and other fabrics you may come in contact with.

8. Calm itchy bug bites

Unfortunately, bug bites and gardening go hand in hand, especially in the hot summer months when mosquitoes are at their peak. Most people know that when a mosquito bites you, it takes some of your blood with it. But did you know it’s their saliva that they leave behind that causes a mosquito bite to itch? Their saliva contains proteins that are foreign to your body’s immune system. Your body releases histamines to fight off the foreign material, which leads to the itchiness, swelling, and discomfort that is associated with bug bites.

Scientists are unsure why, but a salve of cornstarch and water is a great fix for this irritation. To soothe bug bites, mix three tablespoons of cornstarch with about double the amount of water to create a thick paste to apply to the affected area. If you get bit by a tick, carefully remove the tick, then apply a similar paste of apple cider vinegar and cornstarch to the area. The vinegar will aid in pain relief and act as a mild antiseptic to help your body fight against infections like Lyme disease.

Cornstarch can be a great, diverse tool in a beginner or experienced gardener’s repertoire. Now’s the time to pull that cornstarch out of the back of your pantry and get to growing!