What Is Powdery Mildew And How Do I Get Rid Of It?

If there are white powdery spots showin’ up on the tops and bottoms of the leaves of your plant, you might have something called ‘powdery mildew.’ This can be easily treated but, if it’s not taken care of, it can bum the plant out and drop down the volume of those oils that make it taste like awesomeness. But mostly it just makes the plant a little fugly (do we still say that?).


No need for a bummed out plant to bum you out. There are a few easy ways to get rid of this stuff. 

What The Heck Is Powdery Mildew?  

A lot of fungal stuff typically gets started in warm and damp environments. At first it shows up looking like dirt or something that can be brushed off, but if not treated, it can make its way back plantside.

Almost all plants are susceptible to powdery mildew but there are some that will more likely get it than others such as: Lilacs, crab apples, phlox, monarda, roses, grapes, squash, cucumbers, and mint. 

How Can I Prevent Powdery Mildew? 

  • Make sure there’s  enough room for lots of airflow between each plant (call it a foot?). Powdery mildew spreads through the air so it can easily fly on your other plants. If your plant’s got it, give it timeout.
  • Give your plant a little more sunlight. It’s telling you it may want it! 
  • Keep the plants properly trimmed and tidy by getting rid or dead or diseased stems or leaves. It also just looks nicer.

“Okay, okay we get it, but how do you actually get rid of it?” 

Well there are a lot of different things you can do and even though it seems kinda strange, mouthwash is shown to be very effective at getting rid of powdery mildew. Mouthwash is made to kill germs, so it kills the spores of the mildew that will continue to reproduce. We may not necessarily endorse it quite yet, but ya never know.. 

What You’ll Need: 

  • Mouthwash: Try plain, inexpensive ethanol-based mouthwash, like this one
  • Spray Bottle: Make sure if you're reusing the bottle that it’s fully washed out beforehand.  
  • Water: That's it!  

How You'll Do it:  

  1. Mix three parts water to one part mouthwash. 
    1. Example: 1 Gallon - Use 4 cups of mouthwash to 12 cups of water. 
    2. Example: 16oz (standard spray bottle) – So that means if you are using ounces, you would mix 3 ounces water and 1 ounce of mouthwash. 
  2. Spray the mixture on the affected areas and wait for 24hrs to see if there are any negative side effects. 
  3. If your plant looks like it’s doing alright, spray the mixture every two-three days until it goes away. 

Here are Two Other Ways:

  1. Baking Soda: Mix one tablespoon baking soda, one half teaspoon of liquid soap with one gallon of water. Mix and spray on the affected areas liberally. 
  2. Potassium Bicarbonate: Mix about 3 tablespoons of potassium bicarbonate, 3 tablespoons of vegetable oil, and ½ liquid soap into a gallon of water. Mix and spray solution on affected areas.   

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