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What Is the White Stuff in Potting Soil? | 5 Secret Reasons!

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Did you just discover that your plant’s potting soil has a film of some white stuff on it? There is no need to worry, as it is typical for indoor plant soil to grow mold in winter.

So, what is the white stuff in potting soil?

“The white stuff in your plant’s soil is probably an unharmful saprophytic fungus.”

Mold spores are present in all soils.

However, your plant just so happens to be creating the ideal environment (warmth, low light, and moisture) for the spores to flourish, resulting in a white chalky substance in the soil.

Due to the wet air trapped in the soil bag, mold grows easily. It usually is undetectable and works to break down organic debris and supply nutrients to the soil.

Let’s explore more about this white stuff and how you can get rid of it.

Read till the end to find more details.

White stuff in plants potting soil—what is the white stuff in potting soil?
What is the white stuff in potting soil? – Image via Reddit.

What Is the White Stuff in Potting Soil? | The Reasons!

Most of the time, overwatering is the cause of a white chalky substance in your plant’s soil.

Other reasons for mold growth are:

  • Mold spores present in the bag of your soil
  • Chilly conditions for its growth
  • Proper nutrition for the mold growth
  • Moisture

All these reasons are discussed further below.

1. Overwatering

Mold spores are already present in the soil, as described in the beginning.

Mold spores will remain in the soil unless it has been sterilized to eliminate all microorganisms.

However, they will flourish if you provide them with a moist environment. That white stuff in your potting soil might either be because of improper storage—if the soil is stored in a damp environment, or overly watered soil.

Based on it, you can assume that the potting media bag contains mold spores already. They just needed the right environment.

You can use sterilized soil to avoid these problems.

2. Sufficient Nutrition Supply

The bagged soil is the food source for the mold.

It usually contains a combination of compost, bat guano, coco coir, dried bark, sphagnum moss, peat, and worm castings. These are the general compositions, although it differs amongst diverse varieties.

The mold spores feed on these goods as much as they want because there is no competition nearby.

3. Ambient Temperature

Next, we discuss temperature.

  • The airtight potting material bags are typically transported or stored at low temperatures, shielded from sunlight.
  • Temperature fluctuation while transportation helps mold spores to flourish.
  • When the time comes to store this soil at room temperature, these mold spores grow in numbers.
  • The ambient temperature sustains these mold spores, which thrive in a small, relatively cool area without any heat to kill them.

The next thing we notice is humidity.

4. Humidity

The water vapors trapped in the soil bag have nowhere to go.

They most likely originated from the organic mix itself or the air while the soil was bagged.

In either case, the mold spores thrive if the bag contains a lot of moisture.This moisture helps mold spores to grow significantly.

5. Sealed Soil

The sealed potting soil bag is a cool, dark, and damp habitat with much decomposing organic matter for the mold spores to feed on.

  • These conditions are ideal for mold growth.
  • Decomposing organic matter in the soil doesn’t imply pollution in the potting soil you bought.
  • Only because of the circumstances did the already existing mold stand out more.
  • In general, this sort of mold is safe for most plants. But in the long run, it does not provide suitable results in favor of the plant.
  • When working with moldy soil, it’s best to use a mask and gloves.

This precaution helps avoid infecting people with weakened immune systems or causing severe allergic reactions.

Is the Mold in Plant Soil Harmful?

Is white fungus in soil harmful?

Mold in a plant’s soil is generally safe for the plant in the short term.

However, it is advisable to scrape it off and throw it away to avoid any long-term issues with the plant’s growth. It consumes nutrition that is supposed to be provided to plants from the soil.

Suppose the mold is not removed from the soil; this white stuff in the soil troubles plant growth and results in the death of the plant.

So, it is necessary to get rid of white fungus from the soil.

While getting rid of this white stuff in the soil, wearing gloves and a mask is essential to prevent unintentional inhalation. For those with impaired immune systems, it might worsen an allergic reaction.

Related article: How To Get Rid of Yellow Fungus In Soil – 8 Methods

How to Get Rid of White Fungus in Soil?

After knowing what white stuff is in potting soil, it’s also crucial to learn how to get rid of it.

Since the mold is not harmful, you can shake the potting soil before using it to re-distribute the spores.

But to get rid of white fungus in the soil, most people frequently take the following actions.

Remove the Moldy Soil

Before using the potting mix, remove and discard the moldy soil areas.

Using moldy potting soil can be unsettling, but it’s simple to get rid of. You can throw it in your compost bin, garbage can, or garden.

Provide Sunlight

Dry your soil, and spread it out in the sun to kill the mold.

It will help if you add heat and adequate ventilation, causing the mold to vanish from your plant’s soil.

If you intend to start any seeds or seedlings, it is strongly advised to use this method.

If not, the mold will fight with the seeds for nutrients, preventing them from ever having a chance to thrive.

Avoid Fungicide

Although it may be tempting, adding a fungicide to the potting soil is unneeded.

  • It’s excessive, and you essentially eliminate other good bacteria in your soil that are essential for the development of your plant.
  • The more direct approach to problem-solving, such as applying strong chemicals, should be avoided because it’s not always the best option.

However, if you want some direct results, add some cinnamon powder to the soil, as its antifungal qualities can stop mold from growing on your potted plants.

Keep the Potting Mix Safe

If you have any extra potting mix, be sure to carefully close the bag and keep it somewhere cold and dry.

Please note the expiration date, so you’ll know it’s still valid when you use it again.

Watch this video to learn more about white mold:

What is the white stuff in potting soil? | White mold on top of soil on houseplants and is it Harmful? – YouTube

Final Words

Since you have been with the article till the end, you now know what is the white stuff in potting soil and how to get rid of it.

  • Overall, moldy potting soil is nothing to be concerned about.
  • You don’t need to run out and get a new bag, and these white fungi won’t harm your plants.
  • It’s acceptable to use moldy potting soil or mix to pot up plants, but it’s best to use gloves and a mask when handling it.
  • Watch out whether you are overwatering your plant or not.
  • This fungus is molded and is primarily found as invisible spores.
  • When the surrounding conditions are ideal, they build up into the recognizable, very fine, thread-like, fuzzy mass.

The best option to deal with this mold issue is to buy sterile soil.

Happy gardening!