How to Treat Plant Fungus with Baking Soda

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 insecticidal soap
  3. One tablespoon of baking soda

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

The insecticidal soap helps the mixture stick to the leaves and stems of your plant, but if you do not have it handy, you can use an incredibly mild soap like castile soap. Do not use dish detergent! Some gardeners, myself included, have reported accidentally burning the leaves of their plants with this spray when using detergents. To avoid burning your plants:

  1. Do not apply the mixture on plants exposed to full sun, particularly during hot weather.
  2. Water your plants thoroughly the day before application.
  3. Test the mixture on a small section of your plant before you spray the entire plant.
  4. Stick with insecticidal soaps rather than dish detergents.

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 — yes, milk — 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!