How to Get Rid of Mold on Plant Soil

mold in pot

How to prevent and remove white mold on plant soil in pots

No one is pleased to find a fuzzy, white coating of mold growing on their houseplant’s soil. Although such mold doesn’t usually threaten houseplants, mold spores can negatively affect the indoor air quality, and it doesn’t make the best impression. In the majority of cases, it is a harmless saprophytic mold that can be easily and safely eliminated. Here we will advise you on how to remove the mold and avoid its return without harming the houseplants themselves.

Is mold in pots harmful to houseplants?

plant pot mouldThe quick answer is no. Mold and fungi spores are naturally present in small quantities in our homes and make themselves visible wherever they can find food, moisture and the right temperature. Houseplant potting medium is no exception, so white mold on plant soil is not surprising. Such mold is harmless to the plants, but it is not aesthetically pleasing.

On the other hand, the presence of saprophytic fungi can be an indicator that the plant does not have suitable living conditions in terms of light, humidity and air circulation.

How to remove mold from houseplant soil

If mold appears in your pots, follow these steps:

Step 1. Physically remove the mold along with the thin layer of potting medium it is connected to. Use a small shovel or other suitable tool, and if you are allergic to mold and dust, wear a protective breathing mask.

Step 2. Sprinkle ground cinnamon over the mold-free potting soil. Cinnamon contains cinnamaldehyde, which gives it its typical aroma and flavor, but it is also an excellent natural fungicide. Just a light dusting is enough to prevent mold growth.

Step 3. Do not water a plant treated in this way until the top layer of soil has dried out to a depth of at least 5 cm (2 inches).

Avoid the use of vinegar—the mold could survive the increased acidity, while the roots of the plants might not.

Prevention of mold on houseplant soil

Mold can never be completely destroyed. Mold spores are a natural part of the soil and air and are usually harmless. They become a threat when there is high humidity and insufficient air circulation. Under such conditions, they become a factory for the production of more spores. To prevent mold on plant potting soil, follow these rules:

1. Reduce watering

Overwatering is the main cause of mold growth in houseplant pots. Soil that is constantly wet is a good home for mold spores. In general, plants should be watered only when the top quarter of the potting soil is dry. For most houseplants, watering once a week is sufficient. Do not leave water in the trays under the pots for more than 5 minutes and remove any residual water.

2. Reduce humidity and improve air circulation

Moisture and poor air circulation are the main causes of white mold on plant soil. Move your plants to a sunnier location with lower humidity and better air flow. If you do not have such a place, you can improve the growing conditions with artificial lighting and a fan.

What to do with old moldy potting soil

If you store an opened bag of potting medium, you may find that it has white mold growing on it when you go to use it again. You may even find mold in a newly opened bag. Is it safe to use such a potting medium for plants?

If you are planting seedlings, transplanting plants or replenishing the potting substrate, yes. However, you should give it a thorough mix and let it air out for two days before using it. You can also add fresh compost to the mix.

A potting medium with visible white mold is not suitable for planting seeds.




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