How to Get Rid of Mold on Indoor Plants and Soil


Owning indoor plants can bring a bit of color to your home and help to improve the quality of the air in your home. They can bring color and life into your living space, but it can be disconcerting when you get mold on your plants. Some mold can be harmless while other types of mold can kill your plants, and people who are sensitive to the spores can also be affected. 

How to get rid of mold on indoor plants and soil: There are different types of mold that can get on your plants. While those differences matter when it comes to preventing further recurrences of the mold, the removal steps are basically the same:

  1. Remove the mold affected soil
  2. Wipe down leaves and stems to remove mold
  3. Spray to treat the leaves and stems
  4. Treat to prevent mold from coming back

Mold can be very distressing to see on your plants and getting rid of it is just the first step. You also need to take steps to prevent its recurrence as well. Whether you are treating Chinese evergreens or an indoor garden, the treatments are basically the same. Although taking further steps to prevent mold from coming back is just as important as removing the mold itself. 

Removing Mold From Soil

More times than not, the mold that is growing in the soil of your plant is not harmful, neither to humans nor the plant that it is growing with. Living soil, or soil that has microorganisms growing in it can be the healthiest soils for your plants, but this can also mean that soil that the right conditions could also cause those microorganisms to flourish in a bad way. 

Although this is usually not actual mold, it does have the appearance of mold. Usually, it is a type of fungi. This fungus has probably been in the soil since you bought it. It is not harmful for the plant in general, but there are certain situations where it may cause problems for some plants. If you are concerned about it, you can easily remove it. 

When you grow plants indoors, this mold or fungus can become problematic for the humans living in the house. For people who are sensitive to mold spores, such as those who get rhinitis often, those who have asthma, or those who have frequent allergy issues, the mold spores cause breathing issues or just make life miserable. If this is the case, removing and preventing mold needs to be done for health reasons. 

Removing and preventing mold is not difficult, but it can be time consuming, depending on the number of plants you are dealing with. Even if only a handful of your plants seem to be getting moldy, you should treat all of them. Mold spores could have spread from the affected plants to the others even if there are no visible issues yet. 

How to Treat a Mild Infestation of Mold

For a mild infestation of mold or fungus on the soil in your plants, all you need to do is remove the contaminated soil. Treating the problem before it gets out of hand will save you the trouble of fighting a massive infestation later. This will not just save you time, but also money in the long run. 

  • Using a small spoon or scoop, you can remove the top ½ to 1 inch of soil. This will remove any fungi or mold that is currently in bloom or growing. 
  • Be sure to replace any soil that you removed. You want to ensure that the roots of your plants are completely covered. 
  • You can treat the soil with a light dusting of cinnamon or baking soda to prevent mold from recurring. 
  • Be sure that you do not water the plant too heavily in the future as moist soil enables growth. 
  • Wait until the top ½ inch to two inches of the top of the soil is dried out before watering (depending on the size of the pot).
  • Consider a new place to set your plant to ensure it gets more light to dry the soil faster. 
  • Adding ventilation can help the soil to dry faster as well. This will help to prevent the mold from returning and an infestation from happening. 

Mild infestations will tend to be confined to just a few plants and have not had a chance to spread to all of them. It is better to treat all of your plants, even those that do not seem to be affected as of yet, just to prevent an issue before it arises. Even if the mold is just on the soil at this point, mold can travel on air currents, and it can eventually grow up to the leaves. 

Treating 10 or 15 plants just means taking an extra couple of minutes that can prevent a bigger issue down the line. It not only saves time and money in the long run, but it can also prevent any issues from spreading, even if they do not seem like they have yet. A plant can easily be infected, even if it does not look like it as of yet. 

How to Treat an Aggressive Infestation of Mold

For a more aggressive infestation of mold in the soil of your plant, you may be forced to repot your plant. If the mold has grown deep enough or significant enough, you will need to replace the soil entirely. This would be a good time to check the roots of your plant too, to make sure they are healthy and have not yet been infected by the mold. 

While many sites may recommend sterile soil, this may not be needed. All soil, at some point, will get mold spores in it. That’s just a fact of life for a plant. If the mold grows out of control, you will just need to get rid of the old soil and replace it with fresh potting soil. This does not mean that you have to throw it in the garbage though, you can use it around outside plants instead. 

I would not recommend soil from your garden as that can contain more than just mold spores and could very well kill your houseplant. Soil from outside can contain weed seeds, insect eggs, and harmful bacteria. All of which could be detrimental to your houseplants. Putting soil used for your indoor plants outside is ok, but it is never ok to bring outside soil inside due to the risks. 

The best way to repot your plant is:

  • Remove the plant from existing soil. This soil is no longer safe to use with indoor plants, but it can be placed around outdoor plants or trees for added nutrients to the soil in that area outside. 
  • Carefully clean all of the existing soil from around the roots. You can gently spray the roots with either water or compost tea mixed with some milk to help clean them and inhibit mold growth on the roots. 
  • Clean the pot to ensure that any potential mold spores have been removed and spray with apple cider vinegar. This will help to inhibit the growth of any existing mold spores that you were unable to remove. Rinse the pot with water before replanting to ensure that you remove the apple cider vinegar and dry thoroughly. 
  • Replant your houseplant back into its now clean container and fill with healthy, clean soil. If it seemed like it was starting to grow out of its previous pot, planting into a bigger pot may be a good option at this point, rather than having to repot it again in another month or so. Again, it’s all about saving time while you are treating your plants. 

Removing Mold From the Leaves

Mold on the leaves of your plant can be a bit more serious as it is no longer the nutrients in the soil that the mold is feeding on. In this case, it is the nutrients contained within the plant itself that the mold is feeding on. This can be detrimental and is usually not the same kind of mold that grows on or in the soil. Mold that grows on the leaves of a plant is harmful and needs to be removed as soon as it is noticed.

One of the best and easiest ways I have found to remove mold from the leaves of a plant is just a damp paper towel. You can spray water on the plants too, to help keep the mold spores from being airborne, but make sure that the paper towel is at least damp to ensure that the spores attach to it instead of being spread around your environment. 

Use a new paper towel or at least a new section of paper towel, to wipe each leaf. Otherwise, you may just end up transferring the mold spores from one leaf to another. 

Even if you do not see mold on your plants, it is best to wipe them down once or twice a month anyways to remove any dust or dirt that gets on the leaves. Dust can actually inhibit photosynthesis and prevent the plant from thriving in an area that would otherwise be perfect for it. This would also be a good opportunity to check for mold on your plants as well. 

Preventing the Return of Mold

Once you remove the mold, you will want to take measures to ensure it does not return. This can be done in a number of ways from treating the soil to moving where you keep your plants. 

Preventing the mold means removing a few things from the equation where plants are concerned. The biggest thing is to remove moisture. While you obviously can’t just stop watering your plants, you can do things to make sure that the water does not just sit and the soil stays damp for long periods of time. 

More sunlight can help to dry up the top of the soil better, as can better circulation or ventilation around the plant. Moving air can help the top soil to dry faster without pulling the moisture from the deeper soil. It can be difficult to be able to find that balance between making sure your plant has water and keeping it from being too wet for too long, especially in the wintertime.

Treating the Soil

One of the best ways to prevent the return of mold is to treat the top of the soil, where the mold is most likely to grow. Treating the soil to prevent the return of the mold is so simple you just may wonder why you didn’t do it to begin with. 

Top it with Cinnamon – You can sprinkle cinnamon on top of the soil to inhibit the growth of any mold. In addition to inhibiting the growth of mold, cinnamon can make your house smell nice. You do not need a heavy dose of it. Using a bottle that has the little holes in the lid, you can sprinkle a small amount across the top of the soil, just like you would your toast (minus the sugar). 

Baking soda –  Similar to the cinnamon trick, you can use baking soda instead of cinnamon on top of the soil. Sodium bicarbonate is used by a lot of green thumbs to protect their plants and some that grow roses state that it can even be used to prevent black spot disease. While baking soda can be put on top of the soil, it should not be mixed in as it can change the acidity of the soil. Again, you don’t need a thick layer, and a shaker can help with keeping the layer thin. 

Apple Cider Vinegar – Mix 4 Tablespoons of vinegar with a gallon of water to limit its acidity. You can lightly spray the top of the soil once a week or so to prevent the growth of mold on the soil. While I would not recommend using apple cider vinegar to water your plants, a small amount will not harm the plant or the roots if used lightly. 

How to Prevent Mold on the Leaves

There are a number of ways to prevent mold or white powdery mildew from spreading to, or growing on, your plant’s leaves and stems. By preventing the mold from being able to take hold, you can prevent any potential damage to your plant as well.

Sodium Bicarbonate

Ingredients:

3 Tablespoons of Sodium Bicarbonate (baking soda)

3 Tablespoons oil

½ teaspoon dish soap

1 gallon water

Mix all the ingredients together in a gallon jug. You can use warm water to help the sodium bicarbonate dissolve, just make sure it cools to room temperature before you use it on your plants. Carefully pour into a spray bottle (use a funnel if you have one) and lightly spray all of the leaves, branches and stem. 

Be careful about spraying too much at a time. If too much sodium bicarbonate gets into the soil it will change the alkalinity of your soil, which could be bad for your plant, depending on the starting alkalinity of your soil. 

Vinegar

While both white vinegar or apple cider vinegar can be used to treat and prevent the powdery white mildew, caution should be taken because vinegar, in any form, can burn the leaves if not properly diluted first. 

4 Tablespoons with a gallon of water is all that is needed. Using at a lighter solution is recommended if you plan to spray daily, which may be needed if you had a heavy infection on the leaves. Otherwise spraying once every three days should be sufficient to treat most infestations, then once a week or once every other week to prevent recurrences.

Milk

Now this one may be as surprising to you as it was to me when I first heard of it. Never one to simply take someone’s word that something is good for my plants, I did do some research on it and found that not only was my friend right that milk could be used to prevent mold on my plants, but it can be used in conjunction with compost tea to treat the soil as well. 

By simply mixing 3 parts water with 2 parts milk, you can make an effective spray for your leaves, but through my own research, I found that you can also use it with the soil too. Swap out some or all of the water in this recipe with compost tea to fertilize your soil without impacting its acidity. 

While milk itself is nothing to write home about as far as fertilizer goes (at least from my research), it does seem to have a positive effect on protecting both plants and soil from mold. By adding in the compost tea, I have found that I can spray down my plants and not worry about what gets in the soil, unlike the sodium bicarbonate method. 

This does allow me to cut down on how much work I have to put into my plants. Since I am spraying once a week for mold, adding in the compost tea allows me to fertilize, just a bit each week as well. This helps to keep the nutrient level pretty steady without having to worry about adding chemicals to the soil and risking burning the roots if I use too much. 

Commercial Fungicides

While you can use commercial fungicides, if you are trying to stick with more natural remedies, I would stay away from them. I thought it prudent to include it in this list as it is an option. While it is very effective, some precautions do need to be taken, especially if you have young children or curious pets. 

Unlike things like milk or vinegar, commercial fungicides do need to be kept out of reach of children and pets as it can be dangerous. For any plants you intend to use for consumption, you will want to avoid the use of commercial fungicides. If you do use a commercial fungicide on these plants, you may be ingesting some of it along with your veggies.

Commercial fungicide can also be more expensive and more of a hassle to work with, not just because of the potential of poisoning, but also with the potential damage to the plants because the commercial variety also tends to be stronger. Make sure that if you decide to go this route that you closely follow the directions on the bottle. 

What Causes Mold to Grow

Mold, like mildew, is caused by dark, moist conditions. This is actually how you end up with mold in the fridge on fruits and veggies because all mold needs to grow is liquid, nutrients, and darkness. In the case of plant matter in your fridge, it gets the moisture right from the fruit along with the nutrients, and a fridge tends to be dark, so it becomes the perfect environment. 

The same translates to your houseplants as well. The soil of houseplants is full of nutrients, frequently wet, and does not always get enough light. Bright, warm conditions are not conducive to mold or fungus to grow on your plants or in the soil. 

Reasons to Remove Mold

While in general, mold on plants is not dangerous to humans, some people that are sensitive to mold spores can have a reaction to the mold. For this reason alone, you want to make sure to keep mold growth under control. For some people, exposure to mold can become a life threatening situation. 

There is also an aesthetic reason behind removing the mold. It can just make your home look and smell dirty, even if it is otherwise spotless. Even if mold does not currently bother you, it could in the future, the more you are exposed to it. 

Eventually, mold can kill your plants by starving it of the nutrients it needs to survive, so you will definitely want to remove it.

Tips

In the research I did when trying to get rid of the mold on my own plants, I found a few things that may be of interest to you. While they do not deal directly with getting rid of mold on houseplants, it may help you to prevent it from starting in the first place. Sometimes it is about preventing an issue before it can start rather than waiting and treating it afterward. 

New Plants

Using fresh or clean soil with new plants may be a way to help prevent mold from growing on the soil in your plants. You can either use commercially available potting soil, or you can use soil you have made from composting materials. While it may be impossible to prevent mold entirely, it can be possible to reduce the risks by using soil that has had limited contact with mold spores. 

Before bringing new plants into your home, check existing plants to make sure that you are not dealing with mold on any of them first. This way, you do not spread mold to new plants that may not be hardy enough to survive a mold infestation. Young plants are especially susceptible to mold due to their higher need for nutrients than more well established plants do. 

Check any new plants that you bring in to make sure that you do not have mold growing on the soil or the leaves. By doing this one little step, it will take almost no time, but can prevent a lot of wasted time in fighting mold that may come in on new plants. You can save a lot of time and energy by checking the plants first. 

New plants that have mold on them can still be brought into your home, but they should be treated before you even bring them near your existing plants. You may also want to keep them in a separate room, away from your existing plants, just to make sure that the mold spores do not transfer from one plant to another. 

Established Plants

While mold can happen year round, it is more likely to happen as the days get shorter and the temperatures drop. As we go through fall into winter, you will want to pay closer attention to your plants, checking them weekly as the winter goes on to make sure that you are not getting mold on your plants. By doing this, you can get it as it is starting before it can take hold.

As temperatures fall, this means that moisture will not dissipate as quickly. This leaves more moisture for mold to use to grow with. The best way to prevent mold from growing as the moisture is not evaporating as fast is by limiting how much you water and when. Never leave a pot in standing water either as it will keep the soil moist longer. 

Move plants towards more light sources or increase the light used. Mold needs darkness to grow, so the less darkness, the more likely your plant will stay mold free. Plants that spend more time in darkness also need to be checked for mold growth. 

Pay attention to humidity levels as well, as high humidity can mean more opportunity for mold growth. Some plants may need higher humidity, such as marijuana, but this higher humidity means a higher chance for mold growth. When growing plants that require higher humidity, check weekly for mold growth to stop it before it spreads to all of your plants. 

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