Powdery mildew translates to destruction and havoc in your indoor garden. Taking preemptive measures can save you a whole lot of trouble! – Gro Indoor
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How to Identify, Treat and Prevent Your Plants from Powdery Mildew

by 09 Apr 2023

How to Identify, Treat and Prevent Your Plants from Powdery Mildew

Let's imagine a scenario. You leave your plants healthy at night, and when you check them in the morning, you see powdery white spots on the leaves. You'd probably panic. And rightly so. These spots are commonly known as powdery mildew and are a relatively common fungal infection.

Now that you have seen your plant is infected, you need to learn how to get rid of it. But before that, let's learn about powdery mildew and what preventative measures you can take.

Understanding Powdery Mildew

Powdery mildew airborne, rapid-spreading fungus is a common enemy of indoor gardens. While it is easy to get rid of, the fungus grows rapidly, and that is actually dangerous. If not spotted and eliminated early, it can take over an entire garden, halts plant growth, and causes buds rot before the plant ultimately dies.

The Appearance of Powdery Mildew

You can easily spot powdery mildew as it is very different from other fungal infections. Some common symptoms that you will notice when your plants have been infected by PM are:

  • White powdery patches on leaves
  • Mottling pattern on leaves
  • Leaves becoming pale
  • Upper, newer growth is affected after the lower growth has been affected
  • Drooping and wilting plants

What Can You Do to Prevent Powdery Mildew?

Powdery mildew prevention is very simple. You just have to ensure three things in your indoor garden: no excess moisture, good air circulation, and a functional ventilation system.

Good Air Circulation

If the air circulation in your grow tent or grow room is improper, you are inviting PM to infect your plants. You can use clip-on fans and oscillating fans to maintain good airflow and avoid many kinds of pest and fungus-related problems. Not just that, good airflow is also ideal for strengthening the plant's stems.

You can give our guide to using fans and blowers a look to enhance your knowledge about fans and blowers.

Controlling Humidity

Powdery mildew thrives in excess humidity. Humid environments are breeding grounds for many types of fungi, including PM. During the veg stage, it is recommended that humidity levels be in the 40-60% range for the plants' healthy growth.

If the levels remain in this range, the plants will be less likely to get a powdery mildew infection. But anything beyond this will put the plants at risk. Dehumidifiers can be of great help if you find it difficult to control humidity in your indoor garden or grow room.

Leaf-to-leaf Contact

Another way powdery mildew spreads is through leaf-to-leaf contact. Having a dense canopy means higher humidity levels, which again are not ideal if you want to avoid PM. What should you do? Fewer plants in the grow area and paying attention to detail while pruning.

Defoliation can be great for increasing airflow within the plants and positively impact plant growth. If you prune large fan leaves, you actually increase the potential for growth as other areas of the plant receive more light. However, ensure you don't end up removing fan leaves more than required, as it can result in stunting plant growth.

Proper Ventilation

Lack of ventilation provides PM with a breeding ground. If your plants are already infected by it, and you have poor ventilation in the grow room, the fungus will spread much quicker than it was initially supposed to. Having a ventilation system will ensure that fresh air is brought in through the intake fan, and the hot, smelly air is removed by the exhaust fan every 3-5 minutes a rate ideal for plant growth and prevention of PM.

Two essential parts that make up a functional ventilation system are a HEPA intake filter and carbon exhaust filter the former prevents contaminants from entering the grow tent. At the same time, the latter removes odors from the grow room or grow tent.

Want to learn more about ventilation systems? Here is our guide on setting up grow room and grow tent ventilation.

Treating and Getting Rid of Powdery Mildew

Many growers take all the necessary precautions to prevent powdery mildew (PM)but still find their plants infected. If so, don't worry. We will help you.

Detect early and figure out the seriousness of the outbreak and then take appropriate steps. In case you notice a few affected leaves, just remove them and any other leaves that they might have come in contact with. Then pay attention to the plants and as soon as you spot any other infected part, use a fungicide.

Powdery mildew does not naturally go away and requires special attention, or the situation will only worsen.

Best fungicides for Powdery Mildew

Home Remedies for Powdery mildew

A few home remedies that are totally safe can help you get rid of powdery mildew. All you will need is a fogger or garden sprayer. These include:

  • Baking Soda ("Sodium Bicarbonate" 2 tsp. per gallon)
  • Hydrogen Peroxide 35% (1 tsp. per gallon)
  • Milk Spray (10-12oz per gallon, 1:9 ratio)
  • Apple Cider Vinegar (2-3 tsp. per gallon of water)

Some growers have reported the effectiveness of these methods in solving their problems. However, we still recommend going with scientifically proven techniques for better results. It is not the smartest idea in the world to try things, given the rate at which PM can spread and cause destruction.


As discussed earlier, prevention is definitely better than cure when it comes to PM. If you control your grow tent's environment or grow room, you can almost eliminate the chances of a PM infection. Alongside this, it also helps promote healthy growth of the plants and reduces the chances of a pest infestation, making it a win-win situation for you!

Sep 7th 2022
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