How to Treat Plant Fungus with Baking Soda


As far as plant diseases go, there are none more annoying, frustrating, and hair-pulling than fungus issues. Whether you’re growing microgreens, houseplants, or veggies, plant fungus like powdery mildew can absolutely ruin your plants.

Here’s an example of a classic type of plant fungus, powdery mildew:

Plant fungus treament
Powdery mildew infesting a plant’s leaves. source

Here’s a simple rule to detect plant fungus: If your plant has started showing signs of unusual spotting or has growth on it that is a different color than the plant, it probably has some kind of fungus.

There are a variety of ways to treat fungal problems, fungicides being one of the most common. But, harsh sprays that contain chemicals are sometimes not the ideal way to treat plant problems, especially if they’re inside your home.

If you don’t want to use fungicides, you should consider this simple remedy: baking soda.

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Using Baking Soda To Prevent and Treat Plant Fungus

Before we get into the recipe, it’s important to mention that this remedy is best used as a preventative measure rather than a full treatment. After your plants have been covered in mildew, it’s very difficult to completely remove it. Use this recipe weekly on plants that you know are susceptible to mildew and fungus issues, or if you experience high humidity (which fungus loves).

  1. One gallon of water
  2. One half teaspoon of liquid soap
  3. One tablespoon of baking soda

Make sure you use this mixture quickly and do not store it โ€” it doesn’t keep well.

The liquid soap helps the mixture stick to the leaves and stems of your plant, so be careful not to use too harsh a soap. Some gardeners, myself included, have reported accidentally burning the leaves of their plants with this spray. To avoid burning:

  1. Do not apply the mixture on plants exposed to full sun.
  2. Water your plants a few days before application.
  3. Test the mixture on a small section of your plant before you spray the entire plant.

I’ve also heard gardeners recommend adding horticultural oil to this mixture, because the oil will stick to the leaves and suffocate the fungus. If you want to test this out, go ahead and let me know in the comments if this works for you!

Still Having Plant Fungus Problems?

Like I mentioned earlier, if you are having a hard time getting rid of plant fungus with this baking soda mixture, it’s probably because you have too much on your plant already. It’s best used as a preventative measure. You might need to try more aggressive measures, like the ones found in my guide to treating powdery mildew.

You can also try treating your plants with milk โ€” yes, milk โ€” and seeing if that has any effect. It’s one of the stranger remedies I’ve heard of, but I’ve tried it and it actually does work for me.

Baking soda, soap, and water is one of the safer ways to treat plant fungus issues, especially if the affected plants are inside your home. You really don’t want to be spraying fungicide all over the inside of your home if you can avoid it!

Do you have any remedies you’d like to share? Please let me know in the comments below.

The Green Thumbs Behind This Article:

Kevin Espiritu

Clarisa Teodoro

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33 thoughts on “How to Treat Plant Fungus with Baking Soda”

  1. I tried the milk remedy and it actually worked!! Of course I did spray the leaves early in the morning, and over and under the leaves. In 2 weeks all gone!

  2. Do you know what mistletoe looks like? It is transferred by birds and can be very destructive.
    Does not kill for years or even decades once infested I am unaware of anything other than removal that works. Florel will slow the growth, but it is expensive and not worth the effort in my opinion.

  3. Hello. My fathers has lost 4 trees to this weird looking cluster that attacks new growth. First we lost a very established grapefruit tree, oleander, lemon tree and I noticed yesterday its on another tree. All trees have been taken out. spent hours trying to find something to help. its also attacking our lime tree.

  4. Hi Kevin,

    I am just new entrant in agriculture and exploring my knowledge in chemical less farming.

    I just saw white mildew in garden and planning to use baking soda, liquid soap mixture of infected areas.

    I want to know, Is it mandatory to use liquid soap?

    When we can expect result as I will not use on whole infected areas

    • It’s not mandatory, but it breaks the surface tension of the water so the mixture applies more evenly to the leaf surface – I’d leave it in!

  5. Hi Kevin,

    I am just new entrant in agriculture and exploring my knowledge in chemical less farming.

    I just saw white mildew in garden and planning to use baking soda, liquid soap mixture of infected areas.

    I want to know, Is it mandatory to use liquid soap?

    When we can expect result as I will not use on whole infected areas

    • The liquid soap works to break the surface tension of the water on the plant leaves so you get better coverage. In that sense I would say it’s mandatory, because you want full coverage over the mildewy areas!

  6. I wanted to thank you guys for your suggestions. Have anyone tried coconut oil. It’s a antifungal also camomile tea. I use both for all household and foot fungus. Let me know your thoughts.

  7. I’m curious if these are all outdoor that people are experiencing the white mold like residue. This was all over the tops of my Mom’s trees last year. Seems to be either coming from the sky or what’s in the sky is causing a geeenhouse effect.

  8. I have a cactus that has a lot of gray patches on it. Some, if not all, of the gray is clearly lichen. Is there any way to remove it?

  9. Hi,
    My money plant has been infected with some white sponge like deposits…I’m noticing that the leaves are turning yellow and falling….Can this treatment be used for money plants also??
    It’s kept indoors near southwest facing window. Please help me.

  10. Just want to say Thank You for Posting NON TOXIC Plant Care Ideas. I suffer from extreme Multiple Chemical Sensitivity and can’t be around Pesticides or other Toxic Chemicals. Since my health is getting worse year to year. I am always trying to find Good and SAFE Alternatives. Really Appreciate your page.

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