White mold is among the most common ailments to plague houseplants, microgreens, crops, and the like. If this is your first time to see the thick, fuzzy, web-like substance covering your plants, you may not know which way to turn. If this has happened to you before, you might feel like you have no idea how to keep it from happening again.
Here’s how you can completely get rid of white mold in soil:
- Physically remove the mold from your plant.
- Repot your plant with new soil.
- Clean out your old pot thoroughly.
- Sterilize your planting soil.
- Use natural antifungal remedies.
- Dry out your potting soil.
- Take preventative measures.
This article will guide you through these seven methods that are guaranteed to help you get rid of white mold in soil for good. In the last sections, I’ll provide you with some additional information regarding the phenomenon, including what causes it and the risks it presents to your plants.
1. Physically Remove the Mold From Your Plant
If the infection is minor, you can attempt to get rid of it by physically removing the mold from your plant. I’d suggest using gloves and a face mask before doing so to ensure you aren’t inhaling any of the white mold. Just try to grab the pieces of soil that are infected and toss them (far, far away) out of your garden.
If the infection has already infiltrated your plant, this strategy may prove to be a lost cause. Try to gently brush off what you can, bearing in mind that this infection might have already made it through the soil and into your plant, and it’s way too small for you to see.
2. Repot Your Plant With New Soil
Another quick, non-committal fix is to repot your plant with new soil. As mentioned above, an infestation of white mold could be climbing through your soil and getting all over your new pot. If this is the case, no amount of tedious mold brushing will get all of it off of your plant, and if it does, it isn’t going to keep working for long.
Repotting a plant with some new soil in a fresh pot can help give your crops a fresh start. Just make sure to keep an eye out for any remaining white mold, and try to be proactive rather than reactive to infections.
3. Clean Out Your Old Pot Thoroughly
If you don’t want to move your plant into a new pot, you should still think about replacing the soil and giving your pot a nice scrub. You can use something antifungal, like vinegar (as I’ll cover more in-depth below), to give your pot a thorough scrub down.
Then, replace with fresh new soil as you would in the step above. This time, just pot your plant into the old pot, and voila, you’ve essentially given your plant a bath and a fresh set of clothes.
You can never be too thorough when you wash your pots. This video explains how to clean and sterilize your pots and containers for growing:
Though you don’t have to follow these steps exactly, the demonstration will give you a better idea of how thoroughly you should be cleaning your pots.
4. Sterilize Your Planting Soil
Sterilizing your plant soil is a great way to get rid of pests, infestations, and fungus. It will deplete your soil completely of nutrients, but allow it to reset itself, too. This form of soil recycling can save you significant time and effort.
To sterilize your plant soil, you basically have to freeze or heat all forms of life within that soil. For this reason, you’ll want to remove your plant first and keep it in a safe place, like a temporary pot. If you’re just going to report your plant altogether but want to keep the soil, that’s okay, too. But you need to sterilize it before doing anything else.
Recycling soil works kind of like sterilizing (or, for our science geeks, technically pasteurizing) food or water. You want to get it hot or cold to inhibit the lifecycle of any bacteria, virus, or fungi growing inside. Nothing can survive in high heat, or frigid temperature, for an extended period. For this reason, you should also thoroughly fertilize and mulch your soil after sterilization.
To sterilize your plant’s soil, you can use the following strategies.
Put your soil in a microwave or oven-safe dish for this strategy. For obvious reasons, you’ll want to do this in batches rather than trying to pile everything into the same bowl. Next, you will heat your plant soil to no more than two hundred degrees.
Just like the above strategy, you’ll want to put batches of your soil into a dish or Ziploc bag that you can zip to lock out all air. Then, you will put these bags in a freezer for a few days to inhibit any mold growth or life cycle continuation.
Boiling water is another quick, simple strategy. All you have to do is get your kettle going and then pour hot water over patches of your garden, avoiding plants. Then, you can proceed to mulch and fertilize the area to provide the necessary nutrients back to the soil.
5. Use Natural Antifungal Remedies
Before you dip into the fungicides and herbicides, there are dozens of natural antifungal remedies that gardeners across the world have been known to use. Every gardener has their secret go-to, but I’ll explain the science behind each of them. Possible natural antifungal remedies include:
- Baking soda
- Neem Oil
- Grapefruit Oil
- Food Grade Hydrogen Peroxide
None of these alternatives is necessarily better than the others, but each does have its own set of pros and cons. Weigh your options and see what works best for you.
On a tough day, even if you’re a big believer that neem oil works best, you may reach for the cinnamon just because it’s what you have on hand. Regardless, these natural antifungal treatments will help inhibit mold growth and stop its spread.
Cinnamon, ground or otherwise, has been shown to help plant growth and act as an antifungal in your soil. Now, the plant growth conclusion might be pushing it. The above study found that cinnamon can help stimulate tomato plants (but this may be news you need to hear if you’re a tomato gardener!). But the antifungal uses of cinnamon are undeniable on any plant.
According to the Microbiology Society, cinnamon oil can be used as an antifungal for plant and human use because it damages the substance’s cell membrane and prevents yeast from spreading.
Baking soda has also proven to be an effective mold inhibitor in plants. You shouldn’t sprinkle baking soda on your garden, though. Dilute a teaspoon of baking soda and a quart of water together, and then you can lightly mist over your plant or garden with a spray bottle. You can also add some liquid soap to make it stick to the leaves better.
Using vinegar will be a good go-to, especially if you are worried about using bleach in your kitchen or on your plants. Bleach can help inhibit mold growth, but it is much too strong to use on a house plant. Vinegar has been a natural substitute for bleach in all kinds of kitchen and laundry cleaners, and your house plants are no exception to this principle.
You can use a little bit of apple cider vinegar, wood vinegar, or distilled vinegar diluted with lots of water to spray on your plants and inhibit mold growth. Just like the baking soda tip above, you can add a tiny bit of liquid soap to get it to stick.
You may be surprised to see neem oil under the natural antifungal section. Though it comes in a bottle that makes it look like a weed killer or fertilizer, it’s a naturally occurring substance, and its properties make it the perfect antifungal. The oil helps to prevent the germination of mold spores, though it won’t rid your plants of mold completely. This would be a great strategy to use in tandem with ones above.
Ron Finley suggests using mouthwash as an antifungal treatment in his Masterclass on gardening. He specifically calls out white mold in this suggestion but warns that doing this too often may harm growth. He suggests mixing one part ethanol-based mouthwash with three parts of water and applying it to the moldy areas. This is probably best done with a Q-Tip or brush to not saturate the entire plant.
Grapefruit oil is also widely used for its antifungal properties. In particular, 33% grapefruit extract can deliver excellent results when it comes to yeast-like fungus. White mold can be a yeast-like fungus, thriving in moist conditions, so grapefruit oil or extract may prove to be helpful. Dilute with a bit of water and apply via Q-Tip or brush.
Food Grade Hydrogen Peroxide
Hydrogen peroxide is another widely known cure for fungus (though we use it more for “mold” in our bathrooms, which is essentially the same problem), but few people think about applying it to their plants, especially if they’re growing microgreens or edible plants.
Hydrogen peroxide is another naturally occurring substance that most assume is chemically made because of its name. However, If you dilute the hydrogen peroxide thoroughly enough, it’s safe to spray on your plants.
Healthline suggests using four teaspoons of hydrogen peroxide with a pint of water and then applying a spray bottle to your moldy plant.
6. Dry Out Your Potting Soil
Fungus loves moisture, so drying it out and giving it some sun is a great way to get rid of mold.
Mold grows in places that are dark, moist, and cool. Heat and sunlight are its enemies, so drying out your soil in the sun before even getting it to your plant will guarantee nothing is growing inside of it.
If your mold has already started growing, remove what you can and put your soil in direct sunlight. Depending on the resilience of your plant, you may want to give it a temporary home while you do so. However, if there’s so much mold that you don’t think a day or two with some excess sun will do the trick, it might be best if you remove the plant altogether anyway and give it some fresh, disease-free soil (and even then, the mold may already be inside the plant).
7. Take Preventative Measures
Of course, the best way to get rid of white mold is never to get it in the first place.
I don’t mean this to be a “trick” tip because even the most skilled gardeners can get white mold every once and a while. However, if you follow the steps above and rid yourself of the mold infestation, you do still have the power to prevent the next one. There’s just no way of knowing when the fungus might have otherwise attacked!
Watering Routines & Drainage
You need proper drainage for your soil for many reasons, but preventing mold is one of the most important ones. Moisture and standing water are like magnets for mold. This is why you always need pots with holes in the bottom or something inside the pot to help drain water. It’s also where irrigation systems can come in handy. You should also try to water your plants at a time in the day when they’ll be able to dry (such as in the morning) rather than stay moist.
Additionally, proper hydration is an enemy to mold. Overwatering can waterlog your plants and attract mold. You can use a plant moisture meter or read up on how much water your plant needs to avoid this from happening.
Humidity is a known cause of mold, whether in plants or your home. It can keep your plants moist even after you water them and you think they’ve dried up. If you’ve found mold to be a problem no matter what you do, you might consider getting a dehumidifier. Because your plants still need moisture, you won’t want to put it on your plant rack, rather somewhere near it.
A Miniature Fan
This tip, from the Microgreens Podcast, helps to prevent soil effortlessly. Ventilation is essential because, as mentioned above, standing water or too-moist plants is a common cause of mold. They suggest using a small fan to help dry your plants on those especially hot or humid days.
Small fans, like the USB ones you usually plug into your computer to keep it from overheating, do little but dry things out (you’ll know if you’ve ever attempted to get one of these little things to cool you down). However, the small amount of work they do is enough to keep your plants dry and prevent mold.
What Is White Mold?
White mold looks like what you’d expect. Moldy, thick and fuzzy, covers the length of your plant just like it would your bread. Sometimes, you may not notice it on your plant until it wilts, while other times, its presence is painstakingly apparent. It can appear nefarious, taking over your whole plant, or remain more or less covered.
White mold, in the context of your houseplants and garden, is a fungal disease that affects dozens of plants. It can be caused by overwatering, poor drainage, and humid conditions. White mold is detrimental to plants and crops, and if too far gone, it will result in you having to toss your plant.
White mold affects more than just gardens and houseplants. It’s particularly buggy for sunflowers, vegetables, legumes, and fruits but has a broad ecological distribution, meaning it can affect almost anything, anywhere. Moreover, scientists have had an extremely difficult time creating crops resistant to white mold. So, you can expect to get it at one point or another.
Common Causes of White Mold
White mold is caused by a fungus that thrives in cooler temperatures and moist soil. With the suitable climate and drainage issues, white mold can even spring up mushrooms, which will spore out and affect all of your surrounding plants.
Your plant could’ve gotten infected by this condition while outside because it’s placed under ideal climate conditions for it or because a white mold infection on a neighboring plant got to it.
What White Mold Does To Plants
Whether airborne, created with the perfect conditions, or coming from a nearby plant, white mold spreads like wildfire. It won’t kill your plant automatically, instead, it inhibits its growth and weakens it.
However, if the mold spreads throughout the soil and through the roots, you might be better off just tossing your plant. Large infestations of white mold are more challenging to get rid of by scale, and it might be simpler just to start fresh.
It also bears mentioning that if you find white mold on your plant and are willing to do what you can to revive it, you should still isolate it from other plants. The infection could become airborne and affect more of your houseplants given the right conditions.
White mold can be detrimental to even the strongest plants, which is why knowing how to completely remove it is a piece of knowledge that should be in every gardener’s arsenal. Luckily, as long as you catch the infestation early, you’ll likely be able to rid your soil of it by following one (or more) of these simple steps.