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Curled Monstera leaves are a sign that there’s an issue with your plant, but the good news is that whatever the issue is – it’s still in the early stages.
Assuming that’s the only issue. Although to be honest, these tips will help with a plethora of issues.
Monstera leaves curl when they’re not getting enough water
Light is the main source of a plant’s energy – they convert it into chemical energy to fuel their activities (I lifted that phrasing straight from Wikipedia because it tickled me – I assume it was written by a Stepbrothers fan).
However, photosynthesis is a delicate balancing act – they also need water to photosynthesise efficiently, and if they have plenty of light and not enough water, then their leaves curl to reduce the surface area exposed to the light area.
That way they can make sure they have the correct balance of light and water.
Another reason Monstera curl when they don't have enough water available to them is that they use water to keep themselves upright - it's called turgor pressure. The more water a Monstera has (within reason - we'll cover overwatering later), the higher the turgor pressure and the less curly it'll be.
If this is a bit confusing, imagine that a Monstera has a network of water channels instead of a skeleton. But don’t tell a botanist about that analogy – they will NOT like it.
How to make sure your Monstera is getting enough water
Water it more often
I mean, it makes sense.
I have an article all about watering Monstera here.
There’s so much information out there telling us that we are 100% overwatering our Monstera, that it can leave people that have a history of accidentally forgetting our plants exist for a couple of months feeling confused.
Underwatering is definitely a thing, BUT it's much slower to kill than overwatering, so really, we're the better plant people than overwaterers (not that it's a competition)!
The best way to tell if your plant is underwatered is to check if the soil is wet or dry.
Take it out of the pot (if you can, and have a look). Remember that you, as a human being, have known the difference between wet and dry since you were a child. This is not a trap.
If the soil is dry, the plant needs watering.
I don’t care if you watered it yesterday. If the soil’s dry, water it.
Check that water isn’t hydrophobic
There are a few reasons that your soil can become hydrophobic.
- The soil is too compacted, so the water is just running between the soil and the pot. Water always finds the path of least resistance
- The soil has become too dry – if you’ve ever soaked a coir or sphagnum block, you’ll know that it can take a little while to absorb water.
To make the soil less compact, you can break it up with a chopstick. You might want to add soil amendments like orchid bark to stop this from happening in the future.
To rehydrate hydrophobic soil, you just have to soak it. Get a bowl that will fit the plant pot in comfortably. Then take the plant out of the pot and put it in the bowl - make sure all the soil gets in there. And then just add water to the bowl gradually, waiting a few minutes before adding more. Keep going until it won't absorb any more/you get bored, and then add a bit more and leave it overnight. If the water's gone in the morning and you're confident the soil is evenly moist, then you can put everything back. If you're unsure, add more water and repeat.
Do NOT worry about overwatering at this point. Overwatering is a lack of oxygen to the roots, not too much water in one go.
Check that it’s not rootbound
Being rootbound is rarely an issue in itself – the problem comes from the roots displacing soil, so no water is retained in the pot. If you want the Monstera stay in the same pot, then you can either trim the roots, or soak it (using the method outlined above) rather than watering it traditionally.
Otherwise, just increase the pot size – you don’t need to untangle the roots when you do this – they’ll naturally grow to the moist soil over time
Check that it has an adequate root system
If your Monstera leaves are curling, but the soil isn't dry, just check that it has enough roots to support itself - the issue could still be that it's not absorbing enough water; because it has nothing to absorb the water with.
I have an article on rooting cuttings in water here, which is geared towards propagation, but the principles (getting a plant to grow roots) are the same.
Stop water evaporating from the pot so quickly
This isn’t something I see mentioned too often, but it can be a big issue you live somewhere warm or your plants are beside a radiator or other heat source.
You can cover your soil with rocks – bonus points if they’re white to reflect the heat. You could also cover the whole thing in reflective contact paper or tin foil (covering the top of the soil with tin foil can also dissuade cats from having a cheeky dig).
Or, you know, you could move the whole Monstera into the shade
Ensure your potting mix retains more water
There’s a lot of information out there on how to make your soil more free draining, but precious little on how to convince it to retain more water.
I have written an article about stopping soil from drying out so quickly, but a couple of quick tips are to add more moisture-retaining ingredients like coir and perlite.
Monstera leaves curl when they’re not getting adequate humidity
Monstera are pretty chill when it comes to humidity – they have pretty thick leaves, compared to, say, a Monstera adansonii, but even Monstera deliciosa have their limits.
Monstera get their water requirements primarily from their roots, but they are able to photosynthesis most efficiently when the humidity is around 55% or higher.
The leaves contain water (that turgor pressure again) and if the air is too dry, water in the leaves is utilised to help balance the gas exchange that happens during photosynthesis.
How to increase the humidity around your Monstera so it doesn’t curl
- Add a humidifier
I mean, it makes sense.
- Put your Monstera in a terrarium/plastic box/smaller room
Monstera are usually too big for terrariums, but a big plastic box will do OR move it into a smaller, humid room – somewhere where you dry laundry is great.
- Make the leaves are dust-free
Dust can impede respiration (and attract pests), so wiping the leaves regularly (those makeup remover cloths are best for this) is a great way to stop a lot of issues before they even start.
If you think your humidity is ok, then you can increase turgor pressure by putting a couple of aerial roots in water. It isn’t the most elegant solution (and you’ll need to keep them there to keep the plant, er, pressurised), but it works.
Monstera leaves curl when they have a pest infestation
Monstera typically deal well with pests, but they’re very good at holding on to them, so check your plant over for them regularly.
Monstera are irresistible to a lot of sucking pests, especially thrips, but also spider mites, aphids, and mealybugs. They suck the juices out of the plants, so not only do they lose the chlorophyll that they need to photosynthesise, but they lose water and therefore turgor pressure – no wonder pests make them curly.
How to get rid of pests on your Monstera
There are various ways to try – I like to wash the leaves down with castille soap, but you might also like to try hydrogen peroxide. Bonide systemic granules come highly recommended but they’re not available in the UK so I can’t vouch for them myself.
The key to successful pest eradication on Monstera is persistence. It may take months of bi-weekly cleaning.
Monstera leaves curl when they get too cold
I’m not sure of the biology here, but I’m guessing that Monstera droop wneh they’re cold because they’re trying to preserve their energy. They can’t grow, so there’s little point in photosynthesising more than is necessary to maintain basic functions.
Monstera can live outside in the summer, but frost will kill them, and temperatures much below 60oF/15oC will not be welcomed by them.
Monstera leaves curl when they get too hot
Monstera like a TONNE of light, but they need to be acclimated properly. If Monstera senses that its getting more light, then they can put chemical processes in place to produce more compounds in their leaves that work as kind of a sunscreen.
They need time to do this, so make sure you gradually increase the amount of light your Monstera is getting over time.
But they also need more water when it’s hot, not only because the heat will evaporate it, but because they grow faster and will use more.
If you put your Monstera in a sunny spot and it’s leaves start to curl, move it into the shade and make sure the soil is damp. Obviously hot weather makes soil dry out quicker but things like air movement mean that outdoor plants dry out way faster than indoor ones.
Covering your plant with a cloche or clear plastic bag can help keep the moisture in and the humidity high, meaning less leaf curling and faster growth.
Monstera leaves curl when they get root rot
Root rot happens when there isn’t enough oxygen getting to the roots. Anaerobic bacteria can build up to dangerouse levels and start to rot the roots.
I’ve already touched on why root rot and overwatering can make Monstera leaves curl – the roots are diseased (or have rooted away completely) so the plant has no way to take in water and nutrients.
How to get rid of root rot (and stop it from coming back)
Water less often
It’s perfectly normal to have absolutely no idea how often you should be watering plants when you’re a newbie. There are a tonne of factors that influence how quickly a plant dries out (pot size, soil density, heat, humidity, light, etc, etc, etc).
The reason I think Monstera are a great beginner plant is that they’re pretty resilient if you’ve got one of the above factors wrong. If you follow the rule of ‘water the soil when it’s dry’ you won’t go far wrong (provided you’re not watering with liquid mercury, or trying to keep it on the ice planet Hoth.
Obviously there are exceptions, but this is a plant that is noted for it’s invasive nature. It’s Japanese knotweed with a PR team.
Add aeration to your substrate
If it’s taking more than a month for your soil to dry out, then we need to add some more aeration into the soil. Orchid bar is a good shout, but I also like leca – leca doesn’t break down as quickly as orchid bark, but it’s inert, whereas orchid bark breaks down leaving nutrients in the soil. Use a mix!
It’s difficult to just how much to add, so start with replace a quarter of your soil with orchid bark/leca and see how you go.
Make sure your soil isn’t too compacted
Soil compaction can be a result off too dense a soil, in which case add orchid bark/leca as detailed above.
It can also be a result of overzealous top watering though – especially if you water quickly using something without a spout like a measuring jug. If this is the case, then just stir up the soil a bit with a chopstick. You can also switch to bottom watering.
Ensure that you have the appropriate pot size
Too big of a pot can mean that the soil stays wet for too long, and can quickly lead to root rot. If you only have the one pot, see if you can fill the sides and bottom with gravel/rocks to reduce the volume of water retaining-material.
Monstera leaves curl when they’re still developing
Remember that Monstera leaves are born curly – they enter the world all furled up, and can take a while to straighten out fully and harden off. If your new Monstera leaf is still light green, and is droopy, then chances are it’s not done hardening off, and should straighten out in time.
It’s still a good idea to check that your Monstera isn’t too wet/dry/compacted/hot/cold, but avoid manhandling it too much – new leaves are very delicate and even a light touch can result in a brown mark.
I apologise for such a long read. It’s not my fault – it’s those damn curled Monstera leaves.
If plants had a different symptom for each issue rather than like three symptoms and a dozen issues, we’d all be a lot happier.