This Is Why Your Monstera Is Growing Mould

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If there is mould growing on the surface of your Monstera’s soil, DON’T WORRY.

Chance are, it isn’t doing any harm. It’s a really common occurrence, especially if you have moist soil. However it can point to underlying issues.

Oh, before deciding your plant has mould, be sure to rule out mealybugs. They do look a bit like mould. They could also be mycelium.

What causes Monstera plants to grow mould indoors?

The mould growing on the soil of your plants is most likely to be saprophytic fungi. It feeds on decaying organic matter in moist soil so it’ll urn up if:

  • You don’t remove dead leaves from the surface of the soil
  • You’re using DIY organic fertilisers incorrectly – you can’t just lie a banana skin on top of the soil and hope for the best
  • You’re not letting the surface of the soil dry out properly before watering again.
  • Cold weather and high humidity – you often get mould when the seasons change from autumn to winter or winter to spring

And whilst fungus gnats aren’t usually too much of an issue, an infestation can be a problem. The larvae can end up eating your plant’s roots. And say goodbye to eating without a fly trying to get into your mouth.

Why do Monstera in particular get mould?

They don’t. I think Monstera seem to attract more mould than other houseplants for a few reasons:

  • They’re extremely common, so a lot of people have the same issue
  • Many people keep Monstera in low light. The soil takes longer to dry and mould is more likely to grow
  • Monstera are incredibly resilient to overwatering, so often mould is the first sign that the soil is too damp

What about mould on Monstera roots?

Mould on Monstera roots can happen, and if you’re sure it’s mould, just wipe it off. However, if you’re propagating your Monstera and it has a lot of weird white bumps, that’s most likely primordial roots, which are crazy to look at but 100% normal.

My Philodendrn golden dragon’s primordial roots were very mould-like:

primordial roots on Philodendron golden dragon

What kind of mould grows on house plants?

It’s most likely that your plant has white mould – the saprophytic fungus I mentioned before.

Plants can also have black mould, sooty mould, grey mould, or powdery mildew, but that shows up on the leaves, not the soil.

Should I be worried about the mould harming my plants?

It really depends on the type of mould you’re dealing with. If you just have white mould on the soil, it won’t harm your plants – it just wants to eat decaying matter.

That being said, mould turning up can be a sign that something is wrong – I would gently ease your plant out of its pot and check the roots for root rot.

Constantly moist soil is a sign of overwatering, and if you’ve been overwatering for so long that mould’s moved in, you’re well on the way to root rot.

Overwatering is a curse, so I’ve written a post on how to stop doing it.

There are other moulds that can harm your plant though, for example, sooty mould deposits can be a sign that your plant is infested with scale, so watch out for that.

Powdery mildew is also…not good, and can kill your plant. It looks like a white powdery film over your plants and covers the leaves, inhibiting photosynthesis and causing stunted growth, or even death.

Is the mould growing on my plants harmful to humans or animals?

No. But be sure to wash your hands after treating it, because you don’t want to inadvertently spread it to your other plants.

Also, maybe don’t let your pet and kids near it. I can’t find anything to suggest it’s harmful, but still. Let’s not take risks.

How can I stop mould growing on my plants?

Preventative care:

  • Check your plants for mould when you buy them
  • Make sure the top of the soil gets a chance to dry out between waterings
  • Try to reduce the humidity in cold weather.
  • Keep a close eye on your plants – aim to check them over a few times a month.
  • Remove dead leaves from the soil.
  • Take good care of your plants – make sure they have enough light, aren’t over-watered, and are in a pot that has drainage holes.

How to get rid of mould:

To be honest, I just leave it now. It’s not harmful. If it bugs you scrape it off with a spoon. I don’t think it warrants a full repot.

I would check the roots and soil, just to double check that you’re not overwatering.

Before you go, you might find these articles useful:

Caroline Cocker

Caroline is the founder and writer (and plant keeper) of Planet Houseplant

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