I’m sure you want to keep mold away from your house, we all do. Well, I have good news and bad news for you.
The bad news is that most of us are exposed to mold every day, no matter how clean the house is, as it can quickly grow on moist surfaces and release spores into the air, which can be inhaled.
The good news, however, is that in these types of situations, mold is found in small amounts and it is usually harmless.
So moist surfaces cause mold growth and some houseplants require a humid environment to grow, which begs the question, can indoor plants cause mold as well?
Yes, indoor plants cause mold sometimes, however they don’t cause common household mold. Plants cause white mold, also called mildew or powdery mildew. Although powdery mildew is harmless for healthy humans, it indicates a fungal infection and can cause health issues in plants, especially if it’s growing on the leaves and stems of the plant.
Let’s take this further and unravel the topic.
First of all, what is mold? We’re talking about two types of mold in this article – mold and plant mold (or mildew). But how are they different?
Technically, mold is usually referred to as household mold, the one growing on our bathroom walls or clothes and usually comes into shades of white, red, green, brown or black.
Mildew, or plant mold, is a type of fungus that grows on plants and is powdery white. That’s right, plants are so cool, they have their own type of mold. Well, truth be told, they do share it with other organic matter, such as wood, leather or paper, but they deserve credit for being the most popular living things mildew grows on.
Okay, now we now the difference between the two types of mold.
We also know that household mold is not caused by indoor plants, so from here on we are going to focus on the plant mold (mildew) and its effects on people and plants.
It’s very possible that, if you have many plants in your home, at least once you have seen little white patches forming on the soil area of a plant. This can happen if the soil is moist or damp and the plant sits in a warm environment. That’s plant mold.
A very common case of plant mold is the white powdery mildew, which grows on a plant’s leaves and stems. This can indicate health issues in plants, but have you ever asked yourself: is plant mold (mildew) dangerous for me?
Unfortunately, no type of mold is completely harmless, especially if you suffer from allergies or asthma. However, there is no direct connection between powdery mildew on plants and health issues in humans.
If you are curious about the potential dangers plants can have on your health if you suffer from asthma or allergies, check out this extensive article I wrote on the topic. It also contains a lot of houseplants you might want to avoid if you suffer from those conditions.
While the white mold on plants is not harmful when touched, indirectly, it can harm people by affecting their potential food supplies. Let me explain.
Once grown, powdery mildew can spread very quickly on a plant and if that plant is responsible for producing fruit or vegetables, the produce will be significantly smaller or non existing. This is bad if people rely on those infected plants for their food resources.
Great! Now you know that white powdery mold growing on plants can’t harm you and your family. But what about your plants? Is white mold bad for your houseplants?
Effects of mold on plants
Even though it might not seem as evil as the black mold, white mold, or mildew, can also be malicious. Mildew can affect our beloved houseplants in two different and very distinctive ways:
Mildew growing on the top of the plant’s soil
White powdery mold growing on the plant’s leaves and stems
Mold on plant’s soil
Perhaps you witnessed or know someone who witnessed growing mildew on top of their plant’s soil. I know I did. It can cause panic among plant owners: what is this fuzzy white stuff on the soil of my plant ? Is it going to cause my plant to die?
No, it’s not. That fuzzy white stuff is a harmless type of fungus called Saprophytic fungus, that lives naturally in the soil and sometimes comes up to the surface. It even come up to the soil’s surface because of overwatering or poor drainage. When the soil is a bit more moist than it should be, mildew grows on it.
It is not a pleasure for the eyes, I’ll give you that but there is no need for you to worry about this type of mold, as it has no effect on the plant’s health.
However, be aware, moist soil can attract cockroaches. Read more about it in this article, where I also include an easy homemade cockroach trap which you might find useful if you have this issue.
Therefore, you can leave your worries aside, as white mold on top of your plant’s soil will not damage your plant or cause it to die.
Mold on plant’s leaves and stems
Now this is where it gets complicated. Mold on the foliage of a plant indicates a fungal infection. This is white powdery mildew and if it is not treated in time, it can damage the plant irreversibly.
When mold begins to grow on a plant’s foliage, stems and sometimes flowers, it spreads quickly. For leaves, it starts from the edges and spreads towards the center, eventually taking over the entire leaf.
When this happens, the leaf falls and on the long run, the plant can be emptied out of leaves, so no there will be no food and it will eventually die.
If mold attacks stems, it will cause them to wilt. If this happens, that is your plant telling you it needs help, so be sure you don’t ignore these signs.
While attacking over 400 hundred species of plants, white mold has a particular preference for herbs or other edible foods. Other plants that are easily attacked by white mold are roses, Monarda or the African Violet.
Does mold affect plant growth?
Yes, mold can affect plant growth if it is present on the leaves or stems of the plant. However, if mold is present on the soil and only on the soil, it will not affect your plant whatsoever.
Even though white powdery mold that’s growing on foliage doesn’t seem to have a direct impact on the rooting system of the plant, it can stunt the plant’s growth by attacking its green parts. How come?
If your plant has its foliage attacked by mold, you need to remove it very quickly, that is as soon as it starts growing.
Otherwise, it will spread from the edges of the leaves to the center and eventually take over the whole leaf area, leaving you with no other choice than removing that leaf as it is damaged.
Now, imagine having to remove 70% or more of a plant’s foliage. In that case, the plant’s ability to feed itself will drastically change and its health will be in danger, as well as its ability to grow.
Help! My indoor plant has mold
t happens, even the most experienced gardeners have encountered this situation before. So if this happened to you, what to do?
How do you remove mold on indoor plants?
That’s a good question and, luckily, I come with answers.
Unfortunately, there is no treatment for white mold on plants, but there are some things you can do to get rid of it and salvage your plant. See which case best applies to you.
Mold is present on top of the soil
Danger level: 0/5
If you see white spots on the potting soil of your plant, you might be worried, but there is no reason for you to be. That is called Saprophytic fungus and it is not harmful to plants or people, as it feeds off dead plant cells.
Remove white mold on top of the soil by scraping it off, it should come off easily.
White mold presence on the soil is a sign of overwatering or poor drainage. If you want to avoid its comeback, cut back on watering, check that the drainage system of your plant is working and place the plant in full sun if it isn’t already (unless it is a shade-loving plant).
Useful tip: To prevent mold growing on top of the soil, use good quality, sterile potting soil, that stays fresh for a long time and keeps the plant healthy.
Mold is present on a few leaves
Danger level: 2/5
If you see small patches of white mold growing on a few of your plant’s leaves, I recommend you clean the leaves by gently scraping off the mold.
Milk has also proven to be an efficient mold remover.
Spray the leaves with a solution made of 60 parts water and 40 parts milk to kill the fungus. If most of the leaf’s area or the whole leaf is affected, just remove the leaf entirely, as there is no going back.
This doesn’t necessarily mean the plant is going to suffer tremendously, but it is good to place it in a well ventilated place after cleaning, with good air-flow and sunshine, so it dries out nicely and returns to good health.
Mold is present on the stems
Danger level: 2/5
If your plant’s stem or stems are coated in white powdery mold, don’t panic.
One thing you can do is spray the milk solution (60 parts water, 40 parts milk) onto the affected stems to kill the fungus. Repeat twice a week.
You can also spray 5% apple cider vinegar solution on the stems, as the acetic acid is effective in killing the fungus.
But be careful not to make the solution too strong, otherwise you will burn the stem. Mix 4 tbsp. of 5% vinegar with 1 gallon of water and reapply every three days.
Mold is present in large quantities on many parts of my plant - leaves, stems, flowers
Danger level: 4/5
This is where it gets bad. While in some of these cases, the plant is not salvageable as most parts of it are damaged, you can at least try to restore it by following a few steps.
5 Steps to Save Plants from Mold
Scrape off all the powdery mold, on every part of the plant
Spray it with a milk solution or a vinegar solution (see case 3 for DIY solution recipes)
Place it in full sun to allow it to dry
Once it is clean, you can prevent mold from coming back by applying baking soda solution on the plant’s parts that were attacked by mold in the first place. For the solution, mix 1 tbsp. of baking soda, with ½ tsp. of liquid hand soap and 1 gallon of water. Spray the plant with this solution and then dispose of the solution.
If sprayed with the baking soda solution, move the plant away from the sun to avoid sunburn. You can test the solution on one leaf to make sure the plant can take it.
If these steps did not work for you and most of your plant is still infected with mold, dispose of the affected parts – moldy leaves and stems. If there are any healthy parts left, you might have a chance to still save the plant.
If you do need to dispose of some parts of your plant, here are some tips and an easy guide to recycle houseplants (or parts of it).
I advise waiting for it to come back to health and make sure it has the proper growing conditions: enough water, but not too much and the required amount of sunlight.
Even after trying everything, your plant doesn’t show any signs of coming back, unfortunately you will need to let it go and accept that you lost a plant to mold.
But don’t worry, next time you see mold growing on your plants, you’ll know what to do before it is too late.
The most important take from all this and what you should remember is: if you remove the mold soon enough, you can salvage any plant from mold damage.
Plants cannot cause common household mold, but they can have white mold or powdery mildew.
Powdery mildew is harmless to healthy humans but can be dangerous to plants.
Powdery mildew on the plants soil is usually safe, but if it reaches the stem and leaves, the plant needs treatment before it’s too late.
If you have asthma or allergies and you are curious about what houseplants to grow and how plant mold can affect you, check out this article.
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