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Why Does My Soil have White Mold?

Do you love gardening? Maybe you grow your own food or just keep ornamental plants and own several of them? If your answer is yes, then you must also know how much care and attention they require in order to maintain their beautiful and healthy appearance. When it comes to the “enemies” of plants as well as the soil, mold, more specifically white mold, is the one plant owners most often have to deal with.

Why does your soil have white mold? White mold is a fungus called Sclerotinia that thrives on the soil used in potted plants. This is usually because of inadequate drainage and poor air circulation causing damp and humid conditions. It is the perfect environment for white mold to grow.

What plants does white mold affect?

White mold, which is otherwise known as sclerotinia, is a fungal disease affecting over 360 different plants, such as beans, lettuce, peas as well as brassicas which are members of the cabbage family. House plants are also affected by white mold due to the conditions they are grown. In the case of white mold affecting tomatoes, it is known as timber rot.

Mold symptoms are noticeable on blossoms, leaves, pods, stems, and the soil itself. Leaves will eventually wilt, yellow, and die. And as for the pods, they may rot. Host crops are the most susceptible during flowering, however, young seedlings are under the risk as well.

Mold usually infects the plants early in the summer or spring and with time, keeps developing unnoticed for a while. When the weather is cold, white mold fungus releases spores which can be carried by the wind, infecting other plants in the process. And that is exactly the reason to why it is of crucial importance to catch white mold as well as destroy infected plants in time.

How To Successfully Identify White Mold Damage

White mold symptoms can vary based on the environment as well as the type of plant. However, there are some commonly displayed ones such as:

  • At first, the stem may appear as having a water-soaked part. And at this point of the infection, your plant will still have beautiful appearance; looking healthy above so it is very difficult to detect already occured damages.
  • Wilting of stems, especially at the base accompanied by tan discolouration. Pay close attention as Infected stems may have tan to dark brown lesions.

And from these lessons, you will most likely find a dense, almost cotton-like growth forming under high humidity conditions.

Control and prevention of white mold.

The moment you notice any diseased plants, you need to destroy them immediately. In case of soil infection, remove as much of it as possible and instead, replace it with clean soil. You can try using a barrier such as mulch or plastic for covering the infected ground in order to prevent the spread of disease.

Other methods to control white mold

Proper Watering

Soggy soil invites problems like saprophytic fungi and may even lead to more serious problems such as root rot. A proper watering technique ensures that the plant will get the necessary amount of water it requires without leaving the soil is excessively wet conditions.

You need to water your houseplants only when they truly need it. As a rule of thumb, you should water them in 6-inch pots whenever the soil is dry at the depth of 2 inches. As for the plants in smaller pots, they should be watered whenever the soil is dry at the depth of 1 inch.

Keep adding water slowly and carefully until you notice it running out of the holes which are in the bottom of the pot. As for the excess water draining from the pot, you should discard it promptly.

Cleaning Up the Mold

In most of cases, you can try scraping the mold from the soil surface, placing the pot in a suitable, well-ventilated area in order to ensure that the soil will dry. If you notice that the mold returns or in another case, the soil remains soggy, try repotting the plant whilst using fresh and sterile potting soil.

And remember that before using the pot again, make sure to soak it in a solution consisting of 1 part household bleach and 9 parts water for approximately 10 minutes. Proceed by scrubbing it with water and dish detergent.

Prevent white mold with adequate drainage

Even the best watering technique in the world won’t prevent soggy soil if your pot isn’t able to drain freely. For proper drainage, every plant container needs to have holes in the bottom with the container sitting on a removable saucer which will ensure that it will catch the water while it keeps draining from the pot.

Additionally, you can try placing bits of broken crockery or a layer of small pebbles in the bottom of your pot for improving the drainage whilst preventing bits of soil from ever clogging the holes again. Normally, a 6-inch pot needs 1 inch of pebbles and for a 12-inch container, it requires a minimum of 2 inches. Remember to always check the holes periodically to ensure that they aren’t blocked.

What potting soil should I use to prevent white mold

Try to carefully choose a good quality potting soil containing a mixture of a composted plant material like bark, either perlite or sand as well as peat moss.

Potting soil sometimes contains other materials too, but these three ingredients function as the basis of the potting soil which is able to support the plant, helping with draining freely.

But make sure that your potting soil is both clean and free of insects as well as pathogens like fungi. It is easy to detect contaminated potting soil as it usually has a sour smell.

Open bags of moist potting soil often function as the breeding grounds for insects and microorganisms so sealing the bag before you store the unused portion would be a wise decision.

Remember that even the best potting soil can only last for a year or two. And once it begins breaking down, it can not manage water well, therefore, the soil will end up retaining too much moisture.

To prevent that from occurring, try repotting your plants every two or three years to ensure refreshing of the soil while improving the drainage.

If you do not want to remedy the mold issue by yourself, you can still eliminate the problem completely with one effective proven method – repotting your plant in fresh and sterile soil, ensuring that the old contaminated soil will no longer be there.

Repotting the plant after a white mold outbreak

You can try removing your houseplant from its pot as well as cleaning the container out and then proceed by refilling the container with fresh and sterile soil.

Alternatively, in order to fully remove any of the remaining mold spores, try soaking the container in the bleach solution mentioned above. After that, proceed by rinsing the pot out with the regular dishwashing liquid accompanied with water. And once the pot/container has dried, you can continue filling it with soil and repotting the houseplant.

Consider that before replanting a houseplant, ensure rinsing off the root system as well as cleaning the mold off the leaves. In case of any remaining mold spores, you may end up with recontamination. So it is better to try spraying the plant with a fungicide before you proceed with repotting it. After you have repotted the plant, you need to make sure that you can fully prevent mold growth by adopting an efficient watering and care routine.

Killing white mold with a fungicide

If your plant is contaminated with mold, it will further damage the new soil, contaminating it as the white mold keeps growing. Especially in damp conditions. You can start by removing the mold by hand. Use a damp rag soaked in the bleach solution to wipe over leaves and stems.

Normally, Mold is only found on the soil surface which means that you can try gently scooping the top layer of the damaged, contaminated soil out of the pot.

The next step for further protecting the plant and soil involves applying a fungicide to a plant. If you do not like the idea of buying a chemical fungicide and instead prefer considering more natural options, you can try using Potassium Bicarbonate which is mixed with water.

This organic fungicide works efficiently with white mold spores and spraying this solution over a plant as well as on a surface of the potting soil is enough to ensure the health conditions of both. SB Plant Invigorator is also an excellent product for killing molds, This is an organic soap and I buy mine from Amazon.

Protect houseplants with an anti-fungal spray

In some cases, the soil may need a helping hand for keeping mold and fungus at bay. If you live in a damp or cold area, it may seem difficult at first but even using a natural anti-fungal and adding it to the soil can greatly help with the situation.

There are several nice natural anti-fungal options available. Some great ones include apple cider vinegar, cinnamon as well as baking soda. And rest assured, none of them will ever harm the houseplant providing you do not overuse them.

You can try mixing these into the soil or even sprinkle them on the top surface of your houseplant’s soil. However, make sure not to overdo it as putting too much of it in can harm the soil. A couple of sprinkles or several spoons per houseplant is enough so make sure to keep these amounts in mind. Neem oil or SB Plant Invigorator is both perfect for killing molds and the video below although made for controlling pests with these products will show you how to use them.


As can be seen, there are a lot of effective ways to ensure that both your plant and the soil will no longer be bothered by white mold again. And by implementing these methods while caring for your plants, you’ll be certain that they will stay in both beautiful and healthy conditions, enriching your surrounding environment with beauty and harmony.

I hope you enjoyed this blog post about white mold. I trust it answered your question fully. If this was of interest to you, why not consider checking out some of my other blog posts and subscribing to the blog so you don’t miss future content.

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And remember folks, You Reap What You Sow!