What to Do About Mold on Houseplant Soil

By
Cori Sears
Cori is wearing a black shirt and jeans, holding a large cactus, and smiling in front of large cacti behind her.
Cori Sears

Cori Sears specializes in home decor and houseplants. For more than 10 years, she's been on a mission to transform her urban apartment into an indoor jungle. She's been a contributing writer for The Spruce since 2019.

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Published on 07/13/22
Reviewed by
Kathleen Miller
Kathleen Miller
Reviewed by Kathleen Miller
Kathleen Miller is a highly-regarded Master Gardener and Horticulturist who shares her knowledge of sustainable living, organic gardening, farming, and landscape design. She founded Gaia's Farm and Gardens, a working sustainable permaculture farm, and writes for Gaia Grows, a local newspaper column. She has over 30 years of experience in gardening and sustainable farming.
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A close up image of a fiddle leaf fig tree in a terracotta pot with white moldy soil.

StGrafix / Getty Images

Is your houseplant suffering from a case of moldy soil? Don’t worry, there’s no need to panic. While it may be unsightly, mold on houseplant soil is usually harmless and can be fixed easily. So what should you do when you notice your beloved houseplants growing mold? This is what you need to know.

What Mold on Soil Looks Like

It is not uncommon to notice mold growing on your soil from time to time. It usually appears as small to large patches of white fuzzy mold on the surface of the soil. Moldy soil is almost always accompanied by moist or wet soil conditions.

A dracaena houseplant with white fluffy mold on the soil.

Lena_Zajchikova / Getty Images

Why Houseplant Soil Gets Moldy

The fact of the matter is, mold spores are a normal and healthy part of indoor and outdoor soil and are generally pretty harmless. However, under the right conditions, these mold spores can grow into fungi (the white mold you see on top of the soil) which may begin to compete with your plant for nutrition over time. Plus, it’s just not pleasant to look at. So what conditions lead to mold growth? Here are some things to look out for.

Overwatering

Overwatering your plant can quickly encourage mold to grow. When you are providing your plant with more water than it needs on a consistent basis, the wet soil will present the perfect breeding ground for the dormant mold spores to thrive. To prevent overwatering, ensure that you research how much water your plant needs and adjust your watering schedule based on the time of the year. Remember that most plants don’t need as much water during the fall and winter months since they are not actively growing, and it is easy to accidentally overwater your plants during these months.

Poor Drainage

Proper drainage is essential for houseplants and all container plants for that matter. Most houseplants will suffer if their roots are left sitting in water, and excessively moist soil presents the perfect environment for mold spores to thrive. Drainage can be improved with soil amendments like perlite and sand, which increase aeration, and also by ensuring the plant’s container has drainage holes that allow excess water to escape the pot.

Contaminated Soil

While all potting soil has some microorganisms, it is possible for mold problems to originate from a bag of soil that is contaminated. Soil that has been exposed to moisture and not properly stored can be subject to contamination which can lead to excessive mold growth later on.

A monstera plant in a gold metal pot being watered with a white and gold watering can.

Dmitry Marchenko / EyeEm / Getty Images

Is Moldy Soil Bad for Houseplants?

Generally speaking, moldy soil is nothing to panic about. Mold is a sign that your plant’s soil is rich with organisms. However, it is possible that excessive mold can compete with your plant for the soil’s nutrients over time which could hinder your plant’s growth. The real problem with mold on houseplant soil is that it's usually an indication that your plant is growing in overly moist conditions, which can result in more serious ailments like root rot. Mold is a good indication that there is something in your plant’s growing environment that needs to be adjusted.

How to Get Rid of Moldy Soil

Fixing moldy soil is relatively easy to do and there are a few different methods you can try. If you are worried that your plant doesn’t have enough drainage, you may wish to simply replace all of the soil in order to provide it with a more well-draining mixture. This is the most straightforward way to fix the issue. However, you can also fix the moldy soil without replacing it entirely.

Start by scraping the moldy parts of the soil away and throwing them out. Then, you have a couple of options. Many gardeners swear by using a light dusting of cinnamon on the soil as a natural fungicide, or you can try a baking soda and water mixture as well. If neither of those options works you can also use a commercial fungicide which you can find at most nurseries and garden centers. Most importantly, ensure that you are taking active steps to fix the root issue (pun intended!) to prevent further mold growth in the future.

Preventing Moldy Soil

There are a few ways to prevent mold on houseplant soil which include ensuring your plant has proper drainage, not overwatering your plant, and providing your plant with enough light. When it comes to drainage, using a well-draining soil mixture and the right pot are of equal importance. Always ensure your pot has drainage holes so that excess water does not pool around the plant’s roots. Proper drainage will also help prevent overwatering, but be sure to research how much water your plant really needs.

Tip

Use plastic nursery pots inside of stylish cover pots that don’t have drainage holes. When it’s time to water, remove the plant and its plastic pot and water it over a sink. Once the excess water stops draining from the drainage holes, you can return it to its original spot. 

FAQ
  • Do I have to throw away a houseplant with mold on the soil?

    There's no need to throw out your houseplant if you notice mold on the soil. Simply remove the moldy patches and apply cinnamon as a natural fungicide, or replace all of the soil with fresh soil if you desire.

  • Should I use vinegar to get rid of moldy soil?

    Avoid using vinegar to remove mold from your plant’s soil as the acetic acid can kill your plant as well if too much is applied. Instead, try using cinnamon on the soil which is a natural fungicide, or purchase a fungicide spray from your local nursery to use.

  • Should I throw away moldy potting soil?

    You don’t need to throw away moldy potting soil but it is an option. First, try removing the mold and letting the soil dry out slightly. You can also add some soil amendments like perlite and sand to improve drainage which will help to avoid moldy conditions in the future. Lastly, try treating the soil with a fungicide to remove any remaining mold that may be lingering. If none of this works, you can throw away the affected soil and use fresh soil for your plant.

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