What to Do If Mold Is Growing on Your Houseplant
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While you may be doing everything you can to keep your elegant peace lily, sturdy snake plant, or favorite philodendron thriving and healthy, you may occasionally notice a weird white substance growing in the soil of your houseplants. Seeing mold start to form may be alarming, but the good news is that you shouldn't panic. Mold in plant dirt is actually a common occurrence.
“The white fuzzy or crusty coating is fungi that are always present in soil,” says Justin Hancock, horticulturist with Costa Farms. “Even if growers use sterilized potting mix in the growing process, there are fungus spores in the air, which can land in the pot and begin reproducing.”
The truth is potting mix is a mini ecosystem in which various microorganisms live, so you’re probably going to see this type of fungus from time to time. “It usually doesn’t appear until the growing conditions, such as temperature and humidity levels, are right for reproduction,” says Hancock.
If you suspect that mold is in your plant dirt, here's what you need to know to keep your greenery in healthy condition.
How to Identify Mold on Plant Soil
There are dozens of different types of naturally occurring fungi that may appear on the surface of the potting medium, says Hancock. But typically, mold in plant dirt looks like a fuzzy white substance that appears on the surface of the soil. Sometimes it is white or yellow-ish and crusty.
Causes of Mold on Plant Soil
Mold spores are always present in the air, but mold usually doesn’t appear on the surface of houseplants until the growing conditions, such as temperature and humidity levels, are ideal for reproduction, says Hancock.
For example, most mold appears when the potting medium is too wet, so seeing mold is usually a sign that you may be overwatering your plants.
How Mold on the Soil Affects Your Plants
You might assume that fungi are always bad because many are pathogens that cause plant (or human!) illnesses. But, what’s typically growing in houseplant soil is a type of saprophytic fungi.
Because saprophytic fungi are unable to make their own food, they get their nutrition from dead organic matter. You may also find them in a new bag of potting medium you just purchased (and if you do, it’s fine to use the bag!).
So, is this microorganism going to kill your plant? Thankfully, it's probably not something to be too concerned about.
“It’s unlikely [to be harmful] because the fungus breaks down the organic matter, which releases nutrients that the plant can use. It’s actually beneficial to the plant,” says Hancock. “If you see mushrooms growing on your houseplant’s soil, it’s the same concept.”
What to Do About Mold on Plant Soil
If the mold in your plant's dirt is bothering you, here's what you can do.
Scrape It Off
You can easily scrape off mold in your plant's dirt, but it’s likely just going to recur, says Hancock. It’s always present, though it may not always be visible—and it’s impossible to create a sterile environment in your plant’s pot.
Skip Repotting
Know that repotting your plant won’t solve the issue because the fungus is in the soil. “Even if you rinse off the roots, you’re not going to get rid of it, and you’re just going to stress the plant,” says Hancock. “Repotting is just a waste of time.”
Don’t Use Fungicide
Using chemicals to control the problem is completely unnecessary. “It’s not worth it because the fungus isn’t harmful and is actually improving the quality of the potting mix by breaking down organic matter into nutrients the plant can use,” says Hancock.
Save the Cinnamon for Baking
You may have seen so-called mold-inhibiting hacks on social media, such as sprinkling the affected area with cinnamon. There’s no research proving this method works because scientific studies have examined the effects of cinnamon essential oils on agricultural crops, not cinnamon itself. In addition, topping the soil with cinnamon may invite curious pets to take a sniff or lick, which can cause GI upset if ingested. Also, most essential oils are toxic to pets.
Do Nothing
The bottom line is that it’s totally fine to do nothing! But if it really gets on your nerves, read on to learn how you may be able to prevent fungal growth in the future.
How to Prevent Mold on Plant Soil
The key to dealing with moldy soil is to prevent it from occurring in the first place. Common causes of moldy soil include the following:
Overwatering
Soil that’s too wet provides the ideal growing condition for fungus.
Solution: Go a few more days between waterings, allowing the potting medium to dry out. In fact, most plants are more forgiving of conditions that are on the dry side, rather than being too wet, says Hancock.
Poor Air Circulation
Most of our homes don’t have great air circulation, which can encourage fungal growth.
Solution: Set up a small desk fan to provide better air movement around your plants. This can dry out the wet soil and increase evaporation rates to make the environment less hospitable to fungi, says Hancock.
Low Light Conditions
Fungus often thrives in low-light settings.
Solution: If your plant can tolerate it, move it into a brighter spot in your home with some direct sunlight, says Hancock.
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