Mold On Plant Soil – Causes, Types & How To Kill Plant Mold?


Updated on 26-Dec-2022

Mold On Plant Soil

Houseplants can be a delight to have around, but they do have their limitations. One such limitation is that they are prone to molds and need care.

In Canada, due to cold weather and snowfall during months, Moldy soil can make a houseplant extremely fragile and unhealthy, leading to deterioration of the plant and the surrounding area.

Fortunately, there are many things you can do at home to avoid this mess in your living space. For instance, did you know that watering a houseplant using ice cubes on hot days can help soothe it?

If the weather outside is less than favorable to grow a large outdoor garden, indoor gardening can be an excellent way to bring some nature indoors.

Houseplants are often brought inside to avoid frost damage during cold weather. When they’re re-introduced in the spring, you might notice mold on their soil as a result of this transition. Here’s what it means, and how to address it for a happy home and garden

Below you will learn some handy tips on how to not only identify mold but how to pinpoint the cause and what steps you can take to remedy the problem and prevent it from affecting your plants in the future.

Is Mold on Plant Soil Harmful to People?

fuzzy yellow orange brown grey green plant algae fungal infection compost green algae seedlings seed starting mold remove mold indoor mold spores

Mold on plant soil can potentially be harmful to people if the mold is toxic or if it causes allergic reactions. Some types of mold can produce toxins called mycotoxins, which can cause illness or even death in humans if ingested or inhaled. Allergic reactions to mold can range from mild to severe and can include symptoms such as sneezing, coughing, watery eyes, and difficulty breathing. If you are concerned about mold on your plant soil, it is best to take precautions to prevent the growth of mold, such as keeping the soil moist but not waterlogged, providing proper drainage, and avoiding over-watering. If you suspect that the mold on your plant soil is harmful, it is best to remove the mold and dispose of the affected soil safely.

What Is Houseplant Mold ?

The innocuous white mold is a type of Saprophytic Fungus which is an organism that feeds off and helps to break down organic material. It uses the carbon it gets from organic matter to grow and develop. This is essentially why it likes to turn your damp houseplant soil into a breeding ground.

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Most people do not realize that plants have a natural balance between bacteria and other microorganisms that exist around them. Just as humans have helpful bacteria that live on our skin and in our gut, plants also have a relationship with good bacteria and organisms that live in the organic material of the plant soil.

In outdoor plants, natural processes keep these microorganisms in check so that they do not become too numerous in healthy conditions. However, indoors with potted plants, these bad bacteria can accumulate to toxic levels and kill the good bacteria.

What Are the Types of Mold on Plant Soil?

White fungus on plants

White mold is an uncommon occurrence in soil, but it is caused by the presence of spores which are usually kept in balance.

Yellow mold on plant soil

-The yellow fungus you may find in your garden can be either dog vomit slime mold or mushrooms. These organisms thrive when the soil is warm and moist, whether from overwatering or from contaminated spores that were blown into the area.

Green mold on plant soil

An occurrence of green algae on top of your seedling soil may be an indication of caked and compressed soil, which can result from too much water, being exposed to direct light, inadequate air flow, or high moisture.

Brown mold on plant soil

– Excess moisture in the soil due to overwatering can provide an ideal condition for the brown-rot fungus to develop if any spores are present. This type of fungus prefers wet and soggy conditions.

Grey mold on plant soil

– The presence of grey mold is a telltale sign of root rot or leaf rot in houseplants. The fungus Botrytis shows itself as grey spores around the soil surface and in the most dense parts of a plant’s leaves. This is known as sooty mold.
– Gray mold is a fungus that typically grows on plants that are already weakened or sickly. It’s most often seen on the stems or foliage of the plant.

Blue mold on plant soil

– The mold that is visible in your soil may be a saprophyte, which is harmless. Soil with high levels of organic matter often contains this mold, though it is rarely seen. While it may not be damaging to your plants, it is still important to monitor it.

Orange mold on plant soil

-The orange fungus found in mulch is referred to as physarum polycephalum scientifically and is a type of slime mold. It is a single-celled organism that ingests the bacteria that is created through the decaying of plant matter, thus assisting in the natural decomposition process.

What Leads to Mold Growing on Soil in the First Place?

So what conditions lead to mold growth? Here are some things to look out for.

The following are some of the most common reasons for mold growing on soil in your pots and containers.

Over Watering. Water is the most important component for plant life. Too much water can be deadly for plants. Too much moisture in the potting soil can lead to moldy soil.

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Poor Drainage. If the potting soil remains wet for long periods, the plant will eventually die and begin to mold. Decaying roots, stems, and leaves are breeding grounds for mold spores.

Poor Air Circulation. Mold will only spread if your potting soil is contaminated or infected. This can be particularly harmful for indoor plants that aren’t exposed to outside bacteria.

Contaminated Soil. When you start with contaminated or infected potting soil, the mold will only continue to spread. This can be especially harmful for indoor plants that are not exposed to outside bacteria.

Decomposing Leaves. Dead leaves on potted plants should be removed quickly so that they do not provide additional food for soggy soil mold.

How To Get Rid Of Mold In Houseplant Soil

How To Get Rid Of Mold In Houseplant Soil

When you want to know how to remove white mold on plant soil, these following steps can help you sterilize your soil, clean your plants and remove moldy soil effectively. To deal with mold growing on soil and plants, consider doing several of the following:

  • Remove the bulk of contaminated soil from the plant and wash it off before repotting it in a container with good drainage holes in order to get rid of mold that is actively growing in the soil.
  • The best course of action is to remove the mold completely, in one fell swoop. You can repot the plant in fresh, sterile soil and ensure that the old contaminated soil is no longer present.
  • Clean your houseplant’s pot (you can even spray it lightly with fungicide) and then refill it with fresh sterile soil after you remove it from its pot.
  • If you have any soil that might be contaminated with mold, sterilize and clean it before you use it for planting. Drying out the soil in direct sunlight will eliminate mold spores. Your houseplants need to be kept dry as damp soil is a favorite of mold, so you need to make sure that they don’t stay too wet. You can help your houseplants by using natural sunlight to dry out the soil. UV rays from the sun kill mold.
  • Mold is a common problem, and it’s important to protect your plants from fungus. You can spray them with a safe and effective fungal killing spray, like Fertilome Brand. Keep in mind that not all safe fungicides and molds are organic; you can use chemical fungicides like Fertilome Brand as well. To protect the leaves and stems, simply apply generously over the plant. Or if you want more natural route, try using potassium bicarbonate with water.
  • Adding antifungal to houseplant soil to prevent growth can help keep mold spores at bay. Doing this when plants are added to pots and periodically every year is effective. Cinnamon, apple cider vinegar, and baking soda are all natural antifungal products that won’t harm your houseplant.
  • Use Pots with Good Draining Holes and Monitor Watering- never use pots that can’t be easily drained. If you must, add a thick layer of gravel to protect the soil from excessive moisture.
  • Destroy Infected Plants Before They Spread The Spores Farther– When a plant dies, the mold is still alive and sending out spores that can spread to other plants in your home.
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Hydrogen Peroxide to Kill Fungus on Plant Soils:

Hydrogen peroxide is incredibly useful for plants. It has the ability to eliminate all fungus, molds, and other harmful organisms from the soil. Regular applications of this substance can help keep your plant healthy and free from disease. Having this tool in your plant care arsenal is a great way to maintain a lush garden.

Should I use vinegar to get rid of moldy soil?

Vinegar can be effective in killing some types of mold, but it may not be effective in eliminating all types of mold, particularly if the mold is deeply rooted in the soil. If you are using vinegar to try to get rid of mold on plant soil, it is important to dilute the vinegar with water to a concentration of around 50% vinegar and 50% water. You can then use a spray bottle to apply the mixture to the affected area, making sure to coat the mold thoroughly. After applying the vinegar solution, allow the soil to dry completely before replanting.

It is important to note that vinegar should not be used on soil that contains plants that are sensitive to acidic conditions, as vinegar can lower the pH of the soil and potentially harm the plants. If you are concerned about the effects of vinegar on your plants, you may want to consider using a different method to get rid of the mold.

Other options for getting rid of mold on plant soil include removing and replacing the affected soil, applying a fungicide specifically designed to kill mold, or exposing the soil to sunlight, which can help to kill mold. It is always a good idea to follow the instructions on any product you use and to take precautions to protect yourself when handling potentially harmful substances.

5 Tips To Prevent Mold In House plants


Here are five tips to prevent mold in your houseplants:

  1. Water your plants correctly: Overwatering is a common cause of mold growth in houseplants. Make sure to only water your plants when the soil is dry to the touch, and avoid letting the plants sit in standing water.
  2. Provide proper drainage: Make sure that your plants have proper drainage to prevent excess moisture from accumulating in the soil. This can be achieved by using pots with drainage holes or by adding a layer of gravel or perlite to the bottom of the pot.
  3. Allow the soil to dry out between watering: Allowing the top inch or two of soil to dry out between watering can help to prevent mold growth.
  4. Avoid overcrowding plants: Crowded plants can create a humid environment that is conducive to mold growth. Make sure to give your plants enough space to allow for good air circulation.
  5. Use a well-draining soil mix: Using a soil mix that drains well can help to prevent excess moisture from accumulating in the soil, which can lead to mold growth.

Get Professional Help

Mold thrives when it is exposed to moist conditions. If you want to prevent mold from taking over your home or business, rely on the service of a reputable mold remediation company. These professionals provide comprehensive services and keep offensive spores from spreading.

Toronto Mold removal specialists use industry-approved cleaning solutions and best practices to thoroughly clean up the mold. Skilled crews repair or replace surfaces that are damaged by mold growth as the final step in the reliable and proven mold remediation process.


Ultimate Mold Crew – Mold Removal Toronto