10 Homemade Powdery Mildew Sprays for Plants

Powdery mildew can spread quickly in a garden. Once it takes hold, it can weaken the plants and slow their growth [1].

Thankfully, several homemade sprays can help fight this common plant disease.

Not only are these sprays affordable to make, but they’re also better for the environment than many store-bought fungicides.

Identification

Powdery mildew is a group of fungal diseases characterized by white to gray, powdery spots or blotches on plants [2, 3]. It thrives in humid conditions and areas with poor air circulation.

Left unchecked, this plant disease can significantly reduce your crop’s quality and yield.

Moreover, powdery mildew can affect a wide range of plants. Vegetables like cucumbers, squash, tomatoes, zucchini, and beans are commonly affected.

It may also affect fruit crops such as apples, grapes, pears, strawberries, and peppers. Even ornamental plants, such as roses, zinnias, bee balm, peonies, and succulents, can be affected by this fungal disease.

The Best Homemade Sprays for Powdery Mildew

If you’re wondering how to get rid of powdery mildew naturally, these homemade sprays can help control the disease without relying on synthetic fungicides.

However, always test homemade sprays on a small section of the plant first and wait 24 hours before treating the entire plant.

1. Baking Soda Spray

One of the most popular home remedies for powdery mildew is a baking soda spray. It can limit the spread of this plant disease.

It is often used as a natural treatment to help suppress powdery mildew and other fungal problems on plants.

To make a baking soda spray, combine one tablespoon of baking soda with a gallon of water. Next, add a teaspoon of liquid soap and pour the solution into a spray bottle.

Finally, spray your plants, focusing on all infected areas.

2. Milk Spray

Milk spray might sound unusual, but it’s a proven remedy for powdery mildew [4].

To make a milk spray for powdery mildew, mix one part full-cream milk with ten parts water.

Next, shake it up and spray it onto the affected plants, coating both sides of the leaves. Reapply this DIY powdery mildew treatment every 10 to 14 days.

Milk sprays are especially beneficial because they’re gentle on plants when appropriately diluted.

3. Soapy Water

Soapy water may help reduce fungal growth on leaf surfaces and is often used as a preventive treatment. It is also commonly added to homemade sprays to help them stick to plant leaves.

Therefore, use mild liquid or castile soap, mixing two tablespoons with a gallon of water.

Spray your plants with soapy water every 7 to 14 days to help keep powdery mildew at bay. This method works well as a preventive treatment rather than a cure for mildew on plants.

4. Apple Cider Vinegar

Apple cider vinegar contains acetic acid, which may help suppress powdery mildew.

Mix 2 to 3 tablespoons of apple cider vinegar with a gallon of water, then spray it on the affected leaves.

While this spray can help control white powdery mildew, it’s best to use it sparingly, as excessive vinegar can burn your plants.

Also, apply the solution once or twice a week until the white fungus on leaves clears up.

5. Neem Oil

Neem oil acts as both a fungicide and an insecticide, making it a versatile solution for your garden. It is widely used as an organic pest and disease control agent in organic agriculture.

Therefore, mix 1 to 2 tablespoons of neem oil with a gallon of water and 1 to 2 teaspoons of liquid soap. Spray the neem oil solution onto your plants, covering all the leaves.

This oil works well as both a treatment and a preventative measure. So, you can keep using it even after the mildew disappears to prevent it from returning.

Moreover, you can use it as an organic fungicide for both indoor and outdoor plants.

6. Potassium Bicarbonate

This remedy is more effective at treating powdery mildew than many of the other remedies on this list.

Potassium bicarbonate can quickly disrupt powdery mildew. It also creates conditions that make it harder for the fungus to survive. It is often considered one of the more effective organic treatments.

Mix one tablespoon of potassium bicarbonate with a gallon of water and half a teaspoon of liquid soap to create the spray.

7. Sulfur Spray

Sulfur has been used as a natural fungicide for centuries and remains effective against powdery mildew [5].

Mix sulfur powder with water according to the label instructions to make a sulfur fungicide spray.

Spray on a dry, cool day. However, avoid using it during hot weather, especially when temperatures exceed 85°F, as sulfur can damage plants in high heat.

8. Compost Tea

Compost tea might help reduce powdery mildew. It works by adding beneficial microorganisms to plant surfaces. However, results can vary.

To make compost tea, steep 2 cups of well-aged compost in a gallon of water for a week. Strain and dilute the tea with equal parts of water, then spray it onto the plant leaves.

You can also apply compost tea to the soil to support overall plant health.

9. Garlic Spray

Garlic contains sulfur compounds that also make it an effective natural fungicide.

Follow our recipe to make a basic garlic spray for your plants. Spray it on affected plants.

Test this homemade fungicide spray on a small section of the plant first. Concentrated sprays may damage the leaves of sensitive plants.

10. Hydrogen Peroxide

Hydrogen peroxide also treats powdery mildew on houseplants and outdoor plants.

Mix 4 to 8 tablespoons of 3% hydrogen peroxide with a gallon of water. Next, spray the solution on the plant leaves.

However, test the solution on a small portion of the plant before applying it broadly.

Arber Bio Fungicide

Arber Bio Fungicide is a commercial yet organic option for gardeners looking for a ready-made solution for powdery mildew.

This product also helps fight off white mold, onion downy mildew, and pin rot.

Mix it according to the package instructions, and spray it on your plants.

How to Prevent Powdery Mildew

• Space plants properly to improve airflow.
• Water at the base of plants rather than overhead.
• Remove heavily infected leaves.
• Avoid excessive nitrogen fertilizer [6].
• Grow resistant varieties when possible.
• Clean up infected plant debris at the end of the season.

Takeaway

You can use these homemade sprays to treat or kill powdery mildew. These natural remedies may be most effective for specific plants or under certain conditions.

Different remedies may work better depending on the plant, weather conditions, and severity of the infection. Choose the option that best fits your garden, and monitor your plants regularly for improvement.