Mold On Plant Soil – Why It Appears and How to Eliminate It

It is very common to see a whitish layer of mold appearing in the soil of plants, especially when they are potted houseplants and the soil is a previously acquired mixture. In this article, we will talk about mold on plant soil.

It is normal to panic when discovering mold on plant soil, it does not always mean something necessarily harmful: in small quantities, certain molds can even be beneficial by hindering the development of other undesirable elements for plants. Even so, when mold colonizes the entire soil, it must be eliminated because it becomes a danger to the plant.

Why Does Mold Appear on The Soil of Plants?

The first thing you need to know is that not every time you see a whitish layer on the top of your potting soil it is mold. It is very common that, especially when watered with running water, the soil accumulates over time a small deposit of salts and lime. This is because the plant absorbs nutrients and water from the soil, leaving behind these substances that it does not need. At first, it will look like a kind of whitish velvet, but as it accumulates it will eventually become a brittle layer, which is very easy to remove with your hands and then put some new soil.

If, on the other hand, the whitish layer is moist, it is mold on plant soil. It is also easy to identify by the way it spreads: if it quickly colonizes the entire soil or even the plant, it is undoubtedly fungi.

It is very common for it to appear in mixtures of soils with nutrients, as they provide an environment that also favors its development. Mold will appear in the soil when humidity and temperature conditions are high, which together with the nutrients in the soil will favor mold growth.

In the case of saprophytic molds, they only feed on dead plant matter, so they do not pose any danger to the plant or people. However, an exceptional accumulation of them could form a thick layer on the soil, making it difficult for the plant to absorb water by retaining it. In these cases, it will also be necessary to remove it.

why does mold appear on the soil of plants

How to Eliminate Mold in The Soil of Plants

If you do not know what type of molds are appearing in the soil, and they grow too much or generate bad odors, the best thing to do is to remove them just in case. Some cases of mold in the soil of the plants can be harmful and even attack our plants.

If there is mold in the pot itself, a thorough cleaning will be necessary. Start by removing the root ball from the pot and carefully shake as much soil as possible from the roots. If the roots are affected by mildew, you can also prune them. After this, it will be necessary to use new soil and a new pot, or thoroughly disinfect the pot.

If it is not so widespread in the pot, you can use an antifungal. Ecological fungicides are always recommended more. For example, you should use an organic fungicide like this one (Order it here) and fight mold on plant soil.

It is also important to move the pot to an airy location that is as dry as possible and to reduce watering the plant for the duration of the fungus treatment. Without abundant moisture, it will be much easier to kill the mildew.

how to eliminate mold in the soil of plants

How to Prevent This Fungus

Preventing the appearance of mold on plant soil is as simple as providing those conditions that fungi cannot tolerate: aeration and low humidity. It is not a matter of stopping watering the plant, but waiting for the soil to dry out slightly before watering again will be a great help. In addition, it is vital that, if the plant is in a pot, it has drainage holes so as not to accumulate water.

Regarding aeration, it is sufficient to ensure that the plant is in a location with natural air circulation. However, some species are damaged by drafts, so it is not advisable to do this. In these cases, what we have to do is to slightly remove the upper layers of the soil, where we do not damage the roots. By removing and loosening the soil, it will also aerate naturally, making the development of fungi more difficult.

It is also important to provide the plant with the necessary fertilizer, neither too much nor too little, and always remove the remains of fallen leaves and flowers from the soil or soil. A good option is also to water the plant by dish under the plant instead of spraying water from above, but remember to leave it for only a few minutes and then remove it or put the right amount of water each time, to avoid waterlogging the roots.

how to prevent this fungus
About Henry Morgan

We are the Morgan family, Henry, and Morgan, both agronomists from the University of Michigan, where we met. We are experts in putting our hands in the soil and developing organic foods and improving production processes for decades. Likewise, we have worked for companies such as Mondelez International, BASF, Monsanto, etc. currently in our role as science writers for as well as advisors in promoting large scale food growing in urbanized areas. In this website, we share what we are most passionate about, gardening and farming. Enjoy and see real photos on our website.