How to Use Baking Soda for Fungal Problems?

Stephen Andrews
24 Jan 2023

Sodium bicarbonate can be very useful in the garden. One of its many uses is for fungal diseases that spread on cannabis plants. Depending on the fungal invader you detect in your grow, there are several different baking soda solutions or sprays that can be prepared and used to cleanse and wash the plants.

Most fungal problems occur in places with high levels of humidity. Baking soda is an inexpensive and practical kitchen ingredient that you can utilize to help keep your cannabis plants fungi-free. 

Whether you are growing Cannabis or a vegetable garden, baking soda can work against powdery mildew, black spot fungus, leaf fungus and soil gnats, among other problems.

Powdery mildew

There's a simple solution that you can use to spray the foliage of your cannabis plants and remove the powdery spots. 

Spray ingredients for powdery mildew:

  • 1 tbsp. of baking soda
  • 1 tbsp. of dishwashing liquid (or less for a lighter mix)
  • 1 tbsp. of vegetable oil (for surfactant purposes)
  • 1 gallon of water

How to use it?

Use the baking soda solution to spray plants both indoors and outdoors weekly. Make sure that the solution is well diluted before applying it. Use when plants are not exposed to heat or sunshine. For outdoor plants, that means when the weather is cloudy since soda might lead to foliage burns; for indoor plants, when the lights are off and the plants have cooled. This spray is also very good if you want to wash over vegetables and other garden flowers where powdery spots have appeared. 

Black Spot Fungus

Black spots can destroy the foliage of cannabis plants and cripple photosynthesis. But there's a simple spray-and-wash solution with baking soda for this problem as well. 

Simple solution:

  • 4 tbsp. baking soda
  • 1 gallon of water

Again make sure you use the bicarbonate solution when plants are not exposed to heat or sunshine. The same spray can also be applied to roses and vines in their early fruiting stage. 

Leaf Fungus and Soil Gnats

For this problem, it's also crucial that you first remove the worst affected leaves. For issues around the soil, ensure that you don't overwater your plants. Then there are two different bicarbonate solutions that you can apply to fix this issue. 

Solution ingredients:

  • 4 tbsp. of baking soda
  • 1 tbsp. of castile soap 
  • 1 gallon of water

Mix the liquid solution thoroughly and treat affected foliage and soil as needed.

Alternative spray solution:

  • 1 gallon of water
  • 1 tbsp. of baking soda
  • 2 tbsp. of vegetable oil 
  • Half a spoon of castile soap 

Apply the anti-fungal spray until the fungus disappears. The same spray is also good if you grow tomatoes. 

Happy growing!

Stephen Andrews