How to Get Rid of Powdery Mildew

Updated on December 12, 2017
OldRoses profile image

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.

A watermelon vine that is infected with powdery mildew
A watermelon vine that is infected with powdery mildew | Source

Powdery mildew is a scourge of gardens, both vegetable and ornamental. There are some simple steps you can take to prevent powdery mildew or get rid of it once it infects your plants.

Know your enemy

Although it looks the same throughout your yard, powdery mildew is caused by many different types of fungus, each specific to a particular plant. Fortunately, it cannot spread to different kinds of plants. For instance, the powdery mildew infecting your lilacs cannot infect your zucchini. They are caused by two different fungi.

Fungi grow best in humid weather and shady locations. It infects your plants but doesn't kill them. Powdery mildew is especially a problem in the vegetable garden because once infected, leaves no longer photosynthesize (make food for the plant) so any fruit will be malformed and less flavorful.


The best prevention is to plant varieties that are resistant to powdery mildew. Failing that, do not plant susceptible plants in the shade which encourages growth of the fungi. Plant in full sun and do not crowd your plants to encourage good air circulation. Apply fertilizer or compost in steady quantities rather than in periodic large amounts because the fungi prefers the new fast growing shoots.

Avoid watering from overhead. This will cause soil to splash onto your plants possibly infecting them if fungi is present in the soil. Always water at the roots or use drip irrigation.

It is important that you thoroughly clean up our garden in the fall. Fungi will over-winter in any garden debris that is left on the ground, emerging in the spring to infect your plants again.

Preventative sprays

You can purchase sprays at your local nursery to prevent powdery mildew. They contain sulfur or potassium bicarbonate which will prevent fungi from growing on your plants.

You can make your own spray by mixing 1 teaspoon of baking soda and 1 quart of water. The baking soda raises the pH of the leaves so that the fungus can't grow.

Whether you purchase a spray or make your own, you will need to reapply after it rains.

Eradicating an active infection

Once your plants become infected, it is difficult to get rid of the powdery mildew. Remove any infected plant material so the infection doesn't spread. Either throw it out or compost it.

Anti-Fungal Sprays

Fungicide sprays made up of horticultural oils or plant based oils such as jojoba or neem oils, copper or potassium bicarbonate can be purchased at your local nursery or you can make your own fungicide spray. Mix 1 tablespoon of baking soda in a gallon of water and add ½ teaspoon of liquid soap.

Surprisingly, studies have shown that milk is effective in slowing the spread of powdery mildew on plants that are already infected. Mix 1 part milk to 9 parts water and spray on plants showing signs of powdery mildew.

As with any spray, you will need to re-apply after any rain.

Powdery mildew is ugly but won't kill your plants. Prevention is always the best because once it infects your plants it is difficult to get rid of it and stop it from spreading to other plants.

Questions & Answers

    © 2014 Caren White


      0 of 8192 characters used
      Post Comment
      • OldRoses profile imageAUTHOR

        Caren White 

        4 years ago from Franklin Park, NJ

        Your welcome Pawpaw! The older zinnia varieties are prone to powder mildew no matter how careful you are. One of the features on the newer hybrids is their resistance to powdery mildew. The same with lilacs. I treasured my old-fashioned lilac despite its annual attack of powdery mildew. The new ones are pretty and the leaves stay green rather than turning gray, but they just don't have the same sentimental value for me. Thank you for reading and commenting.

      • Pawpawwrites profile image


        4 years ago from Kansas

        I have a little on some of my Zinnias, which catch a little spray, at the edge of where our lawn sprinklers reach. Thanks for the excellent information.

      • OldRoses profile imageAUTHOR

        Caren White 

        4 years ago from Franklin Park, NJ

        Flourish, so glad that you found it useful. Thanks for reading and pinning.

      • FlourishAnyway profile image


        4 years ago from USA

        This is very useful. Voted up and pinning to my gardening and outdoors board.

      • OldRoses profile imageAUTHOR

        Caren White 

        4 years ago from Franklin Park, NJ

        Peggy, I was surprised about the milk too! Thanks for reading and pinning.

      • Peggy W profile image

        Peggy Woods 

        4 years ago from Houston, Texas

        Thanks for this information about how to treat powdery mildew. That is interesting that milk works in treating it. Good old baking soda to the rescue mixed with water is certainly an easy approach. Living in humid Houston, it can sometimes be a challenge to combat powdery mildew especially since we have a sprinkler system that hits plants with water from above. Pinning to my gardening board.


      This website uses cookies

      As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

      For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

      Show Details
      HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
      LoginThis is necessary to sign in to the HubPages Service.
      Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
      AkismetThis is used to detect comment spam. (Privacy Policy)
      HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
      HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
      Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
      CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
      Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
      Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
      Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
      Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
      Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
      Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
      VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
      PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
      Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
      MavenThis supports the Maven widget and search functionality. (Privacy Policy)
      Google AdSenseThis is an ad network. (Privacy Policy)
      Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
      Index ExchangeThis is an ad network. (Privacy Policy)
      SovrnThis is an ad network. (Privacy Policy)
      Facebook AdsThis is an ad network. (Privacy Policy)
      Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
      AppNexusThis is an ad network. (Privacy Policy)
      OpenxThis is an ad network. (Privacy Policy)
      Rubicon ProjectThis is an ad network. (Privacy Policy)
      TripleLiftThis is an ad network. (Privacy Policy)
      Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
      Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
      Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
      Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
      ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
      Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)