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Broccoli Plant Leaves Turning White – Tips To Fix It

Broccoli is a great next-step vegetable for those looking to expand their knowledge about gardening and try their hands at something trickier than tomatoes. Broccoli is only a bit more challenging to grow because it is very picky on its conditions. One of the things that can frequently happen to broccoli is the leaves turning white.

There is only one thing that causes white leaves on broccoli, and that thing is called powdery mildew. Powdery mildew can spread across the entire plant and thicken.

In this article, we will discuss powdery mildew, why it happens, what happens to broccoli with powdery mildew, how to get rid of it, and more. 

What Is Powdery Mildew?

Powdery mildew is a fungal disease that can attack almost every plant in the garden, including broccoli. Powdery mildew starts as small white spots on the leaves of plants. Eventually, the white spots spread and covered the entire plant in white, dusty mildew. The disease will spread and get thicker; as this happens, the plant has less access to sunlight, and the plant will start browning and dying. 

How To Get Rid of Powdery Mildew On Broccoli

Luckily, out of most diseases out there, powdery mildew is one of the more manageable diseases to combat. You can buy many sprays and other all-natural tricks you can use to get rid of powdery mildew. Let’s take a look.

Potassium Bicarbonate

Potassium bicarbonate is one of the fastest and easiest ways to eliminate powdery mildew. You will probably want to turn to this solution for more extreme cases of this disease. It does come as a fungicide in a spray, but it also comes in a powder form.

Potassium bicarbonate is certified organic and is an all-natural substance. The way potassium bicarbonate works is that it sucks the moisture out of the mildew. 

Follow the instructions on the spray bottle, spraying your plants once a week or twice a week, in most cases. If you use the powder, mix it with water, milk, baking soda, liquid dish soap, or anything listed below. 

Copper Fungicide

Copper may come as a surprise to you since it is a metal. However, it works well with plants by deeply penetrating and clearing the disease. Copper fungicide must be used carefully because if it is used in large amounts, it can be toxic to the plants. In small amounts, it is entirely safe and all-natural. 

Most copper fungicides come in a small bottle, liquid form. Mix the copper fungicide with water (the ratios will be on the bottle), and spray on your plants every 7-10 days until you start seeing results.


Sulfur comes in a dust form and works similarly to potassium bicarbonate. The sulfur works in quickly drying out the mildew. Sulfur isn’t everyone’s favorite cure, as it works better for prevention than treating the disease.

However, it is worth a shot if you are looking for different ways to get rid of powdery mildew. To apply the sulfur, you can take a paintbrush and dip it into the sulfur dust, then dust your plants where the mildew is. You can also pour the sulfur around the base of the plants on the soil. 

Neem Oil

Neem oil has been a favorite amongst gardeners for many, many years. Neem oil works not only for powdery mildew but also for so many bug attacks and other diseases. Neem oil works quickly and efficiently, and it is all-natural.

Neem oil comes in a spray bottle, liquid form. Most kinds of neem oil can be sprayed directly onto the plants; some you may have to mix with water. You should spray your plants every 7-10 days with neem oil. 

Baking Soda

Baking soda is easy to combat powdery mildew, especially if you are looking for something quick. Most people have baking soda. To apply baking soda, mix one tablespoon with 1 gallon of water and one teaspoon of liquid dish soap. Pour into a spray bottle. You can spray as much of this as you would like. 


Believe it or not, milk is another way you can treat powdery mildew. You will want to mix the milk with water in a spray bottle. There aren’t specific measurements; try to have 60% water and 40% milk. You can spray this solution as much as you’d like. 

Hydrogen Peroxide 

Hydrogen peroxide is a great all-natural way to try and combat powdery mildew. Hydrogen peroxide is also very good for plants, as it can help prevent root rot. It is recommended to mix around five tablespoons of hydrogen peroxide with 1 gallon of water and spray it onto your plants.

It is a good idea to spray on a few sets of leaves first, wait a day or two, and check back to see how the solution worked. You can also adjust your ratios and use more hydrogen peroxide. 


Spraying your plants with water probably won’t eliminate the disease; however, it may wash the mildew off the plants for a day or two. Make sure you spray your plants with the water only if the weather is going to be pretty warm, and only spray in the morning so the plants have time to dry off. 

Remove Affected Leaves/Remove Affected Plants

Lastly, if all else has failed, you can always try removing the leaves that are affected by the mildew. You can also remove the affected plants.

You should do this carefully, not sprinkling the mildew dust everywhere on the rest of your garden as you remove the plants. Never put diseased plants in your compost, as this can spread the disease. You should burn the powdery mildew plants or throw them in the garbage. 

Does Powdery Mildew Affect Yield?

If powdery mildew is not treated promptly, it can diminish your yield. The powdery mildew acts as a jacket on the leaves of the plant.

Since the leaves are covered, they are not getting the sunlight they need. This will greatly affect your yield. Your broccoli plants may either not produce anything at all, or they may produce very small deformed broccoli heads. 

If you catch the disease right away, your yield can remain unharmed.

Can You Eat Broccoli That Has Powdery Mildew?

Powdery mildew is a toss-up, something you don’t want to mess with. It may not harm you when you touch it; however, you could be severely allergic to mold if ingested. Besides allergic reactions, broccolis covered with powdery mildew will not be the broccoli you expected. Powdery mildew will make broccoli taste either very bitter or may have no taste at all. 

Final Thoughts

Broccoli plants with white leaves mean you have a powdery mildew problem. Luckily, powdery mildew can be gotten rid of quickly. As long as you get rid of the mildew quickly, your yield will not change, and your broccolis will still taste wonderful. Happy gardening! 

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