Powdery Mildew on Your Cannabis Plants – How to Fix it and then Prevent It

Powdery Mildew: What It Entails, Treatment and Most Importantly, How to Prevent It

powdery mildew on cannabis leaves

There are times you see some white spots on your cannabis leaves, at other times, they are dusted with some white powdery substance that looks like flour. What this indicates is that your cannabis plant has the white powdery mildew or mold infection and something needs to be done to treat it before it gets out of hand. It is usually a minor issue that can be quickly fixed if noticed early, however, it can also escalate into a disaster that will wipe out the entire harvest if not treated promptly.

The powdery mildew is a living organism (fungus) showing as a seemingly harmless powdery substance that manifests on your plant without warning to eat it up and reproduce more of itself on the plant causing it to curl upwards before completely dying out. It is an easily spreading infection that can move from your leaves to the buds and escape the notice of even the most careful growers at any point. It can affect all plants but quite commonly attacks cannabis especially those grown indoors.

The good news is that It is easily noticeable and if caught early, the powdery mildew can be eliminated from your plant with proper treatment. However, it is best to dispose of all leaves and buds affected to prevent a reoccurrence and of the infection

Causes of Powdery Mildew

High Humidity

Having high humidity in your grow area can cause powdery mildew on your plants and this doesn’t necessarily mean water but rather moisture. This is why it is important to regularly care for and check your plants, especially at the young stage when it is necessary to have a moderately humid grow environment. If it is noticed that the environment has high humidity, you can purchase a dehumidifier to control the humidity in your grow area.

Low/No Airflow

When high humidity is coupled with little or no airflow in the grow area, it gives room for powdery mildew to settle and thrive on your plants. The humidity gives it favorable conditions to grow and the lack of airflow encourages it to settle. The elimination of both of these factors will ensure that powdery mildew does not affect your plants. Increasing the airflow of your grow area is a major step towards achieving this, this can be aided by the introduction of an oscillating fan into the area.

Poor Ventilation

Growing your cannabis plant in a tight and unventilated grow area is an invitation to powdery mildew growth on your plant. This often occurs with growers who are short on space and engaged in clandestine growing. It is necessary to change the air in the grow area once in a while.

Leaf-on-Leaf Contact

In growing conditions where your leaves are extremely close to one another to the point of touching each other, it is that powdery mildew will develop as a result of moisture formation. This also occurs in instances where there is new vegetative growth and the leaves are all trying to reach for the light and end up touching one another closely.

Some cannabis growers usually trim some of the fan leaves not only to prevent powdery mildew but also to free up energy for the plant in a bid to increase its yields.

How to Eliminate White Powdery Mildew

Some effective methods can be used in treating powdery mildew infection, this can be in the form of homemade remedies or products with a few of them listed below,


Neem oil


Baking soda

Hydrogen Peroxide

The first step is getting some water and paper towels which are then used in cleaning the powdery mildew off the leaves. This should be done carefully in order not to shake the leaves which could lead to the spread of the mildew. The wetness of the paper towels ensures that you can effectively take it off the leaves when the fungus gets stuck to the paper towels while restricting its spread.

Next is eliminating the airflow and humidity problem, this can be done through the use of dehumidifiers and fans in your grow area. Airflow and high humidity are the major causes of powdery mildew and once eliminated, you can prevent a reoccurrence.

The final step is to select your preferred treatment, mix it with the appropriate amount of water into a clean vessel and spray your plants. It is important to spray all the leaves on the plant even if they have not been affected by powdery mildew to prevent any surprises.

Many treatments for powdery mildew have specific quantities that are to be mixed with water to effectively wipe off any traces of powdery mildew from your plant and it is important to pay close attention to the recommended dosage of treatment before using.







High & Marijuana Blog | Cannabis

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