You love your plants, you take care of them with care and care. Everything is going perfectly well until one day you notice that there is like a white fluff on the substrate of a plant. It seems like something small, almost negligible and 24 hours later you notice that your plant is completely covered with that same whitish substance. Before you run for a can of bleach, vinegar and a brush, today we will explain in detail everything about mold in plant soil. Learn how to identify it, understand how and why it comes out, if it's dangerous for your plants, and how you should act.
What is mold?
"Mold" is a very generic term that we apply to different types of fungi that live in organic matter made up of various microscopic organisms. It grows in places with high humidity and thrives on different surfaces. They help break down dead matter and recycle nutrients. The most common types of mold in the environment are Cladiosporum, Penicillium, and Aspergillus. They reproduce through spores, which travel through the air, water, and even insects. When they reach a place with the right conditions, they begin to multiply.
As you can see, not all molds are created equal. There are some that cause breathing problems and allergies in sensitive people, but others can have positive effects on your plants. The important thing is to learn how to identify them so that you know how you should act.
Is mold dangerous to plants?
Humans instinctively tend to shy away from mold, because our experience with mold is related to negative consequences: allergies, respiratory problems, and surface damage are some of its effects. But when it comes to plants, the result can be completely different. There are fungi that are beneficial for plant growth.
Mold can be of the saprophytic type, meaning it consumes decaying organic matter. As a result of this process, mold breaks down this material into simpler minerals that are of great value to the soil. When you compost, you're basically inviting mold and saprophytic bacteria to devour that waste. For example, the species Trichoderma sp contributes to the development of the plant, while Penicillium or Aspergillus is responsible for decomposing the organic matter present in the substrate, so that various mineral nutrients are released that can be absorbed by plants.
In places such as forests, the presence of this mold is important, as it decomposes organic matter, in addition to recycling minerals to keep the forest in perfect balance, also because it can counteract the action and growth of harmful organisms. But not everything is rosy, because mold can also become a problem.
In some cases,mold on the substrate looks very unsightly, and can produce unpleasant odors, while in some extreme cases yeast can occur. The effects aren't too damaging, but it can be an indicator that you need to pay attention to certain conditions on your plants.
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Why does mold appear in the substrate?
Houseplants are the ones that usually fall victim to this little invader. But for this to happen, certain conditions have to be met that benefit their appearance, because although they are a fairly natural phenomenon, it is not visible in all indoor plants. Precisely for this reason we mentioned that mold more than a problem can act as an alarm, alerting you to certain situations that could be harmful to your plants. These can be:
- The plant does not receive enough ventilation
Mold spores grow happily and multiply in anaerobic conditions, i.e. where there is not much air present. Your plants can be too close together and this doesn't allow air to circulate, so fungi do their thing.
- The substrate isn't well-drained or you're watering too much
Fungal spores travel through the air, they float anywhere, and the reason we don't live covered in mold is because they need a particular condition to thrive: moisture. When a substrate has poor drainage, excess water is not removed quickly, so it will stay moist longer. The same is true if you water too often. If that's the problem, mold is the least of your worries, because the roots of the plants will stop breathing, become waterlogged and rot.
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- Not enough sunlight
If you don't allow sunlight to reach your plants (directly or indirectly, as is appropriate for their species) you will not only be limiting the amount of nutrients they can synthesize to feed themselves through photosynthesis, but you will create a dark environment. moist place where mold will grow fast and blissful.
- You use organic fertilizers
If you add organic fertilizers to your soil just before planting or immediately after planting, you increase your risk of seeing white mold in your plants' soil. This is not negative, quite the opposite. Remember that this organic matter will feed the mold, which will break it down into minerals beneficial to plants.
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- There are dead leaves on the surface
Mold and other fungi feed on decaying organic matter, so if you allow dead leaves to accumulate on top of the substrate, then you're leaving the perfect food for these microorganisms.
What does mold look like in the substrate?
Every plant lover has seen small white spots on the substrate. Many rush to diagnose a mold infection, and then apply any fungicide to the races, which could affect the plant. These white spots may be just limescale or salt deposits that naturally form on the substrate. This is typical of places where the water is very hard, and they can even form a hard film on the soil of the plants.
The difference is simple: check how the white spots are distributed.
In the case of mold, very specific clumps are created, but as it spreads they come together and can cover the leaves of the plants. Lime stains are less defined and delimited and do not grow as quickly. Mold can also be identified by touch, because it is a wet layer, while mineral deposits are dry. On the other hand, there are other types of saprophytic molds that present themselves differently.
Trichoderma, which is a boon for your plants because it inhibits the growth of other pathogenic fungi (such as those that cause root rot), looks like a well-defined white spot on the substrate, which also looks cottony. It is distributed randomly, without respecting any pattern. It's as if white paint has rained down on the substrate and the droplets remain.
Peziza ostracoderma is a saprophytic fungus that looks like a yellowish powder. You won't see it on the surface, but it lodges inside the substrate. It's completely harmless, so if you ever see some cottony yellow spots inside the substrate or a powder, don't worry.
How to get rid of mold in substrate
- Aerate the substrate
White mold is a rather beneficial presence for plants, but for many it is unsightly and if it grows too much it can generate bad odors, so it's normal that you want to get rid of this invader. Depending on your progress, there are simple solutions. If only a few white dots appear, you can mix the soil to aerate the compressed material. This disrupts the fungal growth cycle. You can also expose the plant to fresh air and release the overly compact substrate to dry out the substrate and dissipate odors. Remember to separate the pots a little, so that air circulates between them.
- Do a deep clean
If there's too much mold and it's spread to the plant and pot, it's time for a deep cleaning. Remove the plant, root ball and nail ball, from the pot. Shake it to remove as much of the substrate attached to the roots as possible. Check the roots for another type of fungus or damage, such as rot. The smell is an excellent telltale, so if you find soft, foul-smelling roots, or signs of fungal infection, trim the affected part with a disinfected scissors and proceed with the transplant.
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- Change the substrate and pot
Use a new
substrate and a new pot. If the pot is recycled, I recommend washing it very well, even with a little bleach to eliminate any possible source of infection, not only mold but bacteria or any other pathogen that could be present. The substrate to be used should be well stored, in a place with low light and dry, in a bag or container with drainage that does not admit bacterial or fungal accumulation.
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- Improves pot drainage
Even when you're meeting your watering and humidity needs, it's possible that your substrate is still excessively wet due to poor drainage. This can be corrected in two ways: the first is to mix the substrate with perlite or a little sand to improve the texture. Another way is by correcting the drainage holes, making sure they are not clogged, and even adding a layer of pebbles or pieces of polystyrene to the bottom. If you have a dish to prevent irrigation water from reaching the soil, empty it a few minutes after watering, so that the water doesn't puddle the roots.
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- Use organic fertilizer in the right proportions
If you use too much compost or organic fertilizer, even if you leave it only on the surface without mixing it well with the substrate, it is very possible that it will fill with mold because it is the perfect environment. Correct this by using the proper ratio, which is usually 1 part fertilizer to 10 parts substrate. Mix well, the idea is to feed the beneficial bacteria in the substrate so that they create minerals that are usable by the plants, without overdoing it as this can attract mold.
- Remove the mold and you're good to go
Yes, it's that easy to get rid of mold in plant soil. You just need to dampen a paper towel and use it to collect all those particles or patches of mold present in the substrate. I've used a small shovel to remove that top from the substrate. You can throw it in the trash or put them in the bin. If mold has reached your plant's leaves, wipe them off with a damp paper towel and you're good to go. As we mentioned, mold is not harmful, although it can look bad.
Homemade recipes against mold
There are those who do not want to see mold on their plants, because they find it unsightly or because they suffer from severe allergies to it. To do this, you can use a commercial fungicide, using it in the proportions indicated in the instructions. There are those who opt for homemade options, which can be effective. It's important to know that you shouldn't use vinegar directly on the roots, because mold can tolerate it, but your plant cannot. Here are some homemade recipes for safe fungicides:
- Homemade garlic fungicide. Boil 2 liters of water, add 1 clove of garlic. Let it boil for a few minutes, turn off and wait for it to cool. Spray in the mornings onto the leaves and underside of the substrate.
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Milk-based fungicide: Mix 2 parts whole milk with 8 parts water and 2 tablespoons baking soda. Mix until dissolved and use a spray bottle to apply to the plants once a week.
- Cinnamon powder: Believe it or not, the solution to mold is in your spice pantry. Sprinkle some cinnamon powder directly into the substrate. Not only will this smell delicious, but it will prevent the fungus from growing.