Monstera plants are grown for their monstrous sized and gorgeous split leaves. Curling Monstera leaves are not what you want to be seeing. They should be flat, all green with no yellowing and certainly no curling at the edges.
The leaves should also feel velvety smooth thanks to the huge amount of water contained within them.
Without the high amount of moisture in the Monstera leaves, curling is the result.
It happens when water evaporates from the leaves faster than the plant can use it. It is a moisture conservation behavior associated with many large leaf tropical plants.
What you should be seeing on Monstera plants is lush green fenestrated leaves that look like a rib cage, or Swiss cheese, which is why it is nicknamed the Swiss Cheese plant.
Until the leaves mature, the leaves will not have that distinct rib-like shape. They will be normal leaves without any splits, and it is normal for immature leaves on Monstera plants to curl.
When you have mature Monstera leaves curling, know that it is a defense mechanism of the plant to conserve moisture. The cause is stress caused by moisture loss.
Multiple factors increase transpiration causing water to evaporate before the plant can use it. The symptoms are the same as underwatering despite receiving plenty of hydration.
10 Causes of Monstera Leaves Curling
1 – Overheating
When you notice leaves curling, the first thing to check is the temperature. Despite being tropical plants that thrive in warmth, too much heat will cause water to evaporate before the entire leaf can use it.
The most common cause of high temperature stress for Monstera plants is exposure to direct sunlight. If using grow lights to supplement the plants light requirements, the light can be too close to the leaf surface causing the leaf temperature to rise.
The higher the leaf surface temperature is, the faster water will evaporate.
For reference, the ideal temperature to keep Monstera plants in are between 68oF and 86oF. Outside of those ranges, you’ll experience Monstera leaves not splitting, and they’re more likely to discolor, droop, wilt, die and drop.
Check the plant is getting the correct temperature first, because leaf curling on Monstera is the first sign of heat stress.
2 – Oversized Potting Container
Monstera plants are often grown indoors for the gorgeous gigantic leaves they can produce. However, before they reach that stage, immature leaves will curl. That is natural.
What is not a natural trait is for mature leaves to curl. Putting a young Monstera plant in a pot that is too big for it will cause it to struggle.
With too much soil in the container, oxygen is depleted. The result of that is waterlogged soil. The plant will not be able to soak up nutrients from soil that lacks aeration. The worst risk with compacted soil is root damage. It can result in root rot.
To grow Monstera plants to the point the leaves flatten out and split, do not go too big too fast with the potting container. Gradually increase the pot size by just a couple of inches at a time.
3 – Soil Drainage
In addition to growing Monstera in an appropriately sized container, just as important is to make sure the soil can drain.
Double potting is a good method for Monstera because you can pot the plant up in a container with drainage holes, and place that inside a larger decorative container that contains a layer of drainage material.
Gravel helps improve humidity in larger pots. What happens is the water drains through the container into the decorative pot, the gravel absorbs the water and then gradually releases it as it evaporates throughout the day.
An important ingredient for any potting mix used for Monstera is pumice. It is similar to gravel, however, rather than layering the base of a container with it, pumice is small enough to blend into the potting mix. It improves the soil structure, regulates aeration and prevents compaction, thus, improving oxygenation.
For potting mix blends for Monstera plants, two mixes that work well for drainage and aeration are either 25% pumice mixed with 75% regular potting soil, or, a 50/50 mix of peat moss and potting soil, or alternatively, coco chips in place of the potting soil. Sphagnum moss is an important ingredient for moisture retention.
In young Monstera plants, the oxygen levels are super important, because until the plant matures, it will not have the air roots developed to help with oxygenation. The air roots are the brown roots that emerge from the stems on older Monstera plants.
Until the plant is mature enough to put out aerial roots, the soil absolutely must have lots of aeration to help the roots develop and the stems to be able to use the moisture and nutrients from the potting mix.
4 – Lack of Aeration
Without sufficient air pockets in the soil, the roots will struggle to obtain oxygen. A common misconception of aerating soil in potted plants is that it is enough to poke the soil with sticks to break up compacted soil. That can work, but not for long.
A much better practice for aerating soil in potted plants is to include materials in the potting mix to improve the soil structure so that there is always sufficient air pockets throughout the soil. That is the purpose of including pumice (as noted above for soil drainage).
5 – Dry Air
Dry air is a huge problem for Monstera plants. They are tropical plants and like all of those, they thrive in high humidity.
The absolute minimum humidity level to keep a Monstera growing healthy is 40% humidity. Below that level, Monstera plants stop growing.
This is something to be aware of in the winter months when indoor air tends to be drier. The problem with low humidity is that water evaporates faster in dry air than it does in moisture-laden air.
By raising the humidity levels, the water that is in the leaves remains there for longer. The faster the water content evaporates from the leaves through transpiration, the more likely it is that you’ll experience Monstera leaves curling.
Remember the reason for leaf curl: water conservation!
6 – Air Flow
Monstera plants should not be close to any drafty areas such as frequently used doors or so close to an open window that cold drafts can blast onto the leaf surface, lowering the leaf surface temperature.
If yours is, move the plant to a stabler location that is free from drafts and the curling will rectify within a few days.
An easily overlooked aspect of air flow is fans. Directional fans in particular. As Monstera require relatively high humidity, introducing a fan to the room will move the water saturated air away from the plant.
Without moisture in the air directly around the plant, the transpiration rate increases. The result will be leaf curling, and likely, discoloration, wilting and drooping too.
At the very worst, Monstera plants can experience windburn. The symptoms of windburn are leaves curling and crispy brown spots.
7 – Watering Problems
Watering is tricky to get right with any houseplant because transpiration is affected by so many growing conditions. Excessive light, heat, low humidity and soil conditions can slow down or speed up water consumption from the soil.
Overwatering is a bigger problem than underwatering because too much water in the soil will suffocate the roots, risking killing the plant.
Underwatering is a better problem to have because all that happens when the plant is dehydrated is you’ll see the leaves on Monstera turning yellow, accompanied with some of the leaves curling.
An overwatered Monstera will cause older leaves nearer the base to yellow. When the plant is too dry, every leaf on the plant will exhibit yellowing, starting with the newer leaves that are more vulnerable.
As immature leaves tend to curl naturally, the curling will be more prevalent making it easier to notice the symptoms of underwatering.
8 – Root Bound / Pot Bound
The roots on Monstera plants grow fast. Particularly in the first three to five years. During their early stages of growth, annual repotting is beneficial.
A root bound plant will use more water more quickly. If you find you used to water once weekly, then the soil dries out after two to three days, chances are the roots are too tightly packed in the current container.
Monstera plants do not like to be pot bound. The roots will stretch and wrap around the outer edges of the soil. If you suspect the plant may be pot bound, take it out of its container to inspect the roots.
It is pot bound when the majority of the roots are compacted together around the soil. It will look as though they are trying to escape from the pot.
In extreme cases, the roots will escape from the pot by growing out of the drainage holes. That will severely impact drainage and is definitely a sign that the plant needs a bigger container.
9 – Fertilizer Problems
Never feed fertilizer to an unhealthy Monstera plant. If it is struggling to absorb moisture from the soil, it will have absolutely no chance of absorbing extra nutrients. Water and oxygen are required to keep the plant alive. Fertilizers keeps it growing.
When the plant exhibits unusual behavior such as yellowing or leaves curling, cut back or stop fertilizing, and repot the plant in an appropriate potting mix.
Generally, mature (over 3-years old) Monstera plants that are fed a balanced fertilizer diluted to half strength on a monthly schedule should be repotted bi-annually. The reason for that is because the vast majority of fertilizers are just salt.
After a couple of years, excessive salt accumulation builds up in the soil, reducing its drainage ability which then leads to standing water.
Standing water is never good for any container plant. When it does happen, rarely will it be because of pouring in loads of water, but rather the potting mix being unable to drain efficiently.
10 – Pests
The Monstera plant has a high resistance to many insects, but they are not immune. If all you have are Monsteras in a room, it is rarely a problem.
Pest problems are more likely when you have another tropical plant nearby that has a pest infestation as pests such as mites, mealybugs and aphids can migrate to other plants.
It is for that reason that any houseplant impacted by a pest infestation is quarantined. Without separation, mites, aphids, and other leaf-piercing and sap-sucking insects will migrate to other plants.
To be certain that you have no pests feeding on the juices in the leaves (causing them to appear underwatered), inspect the underside of the leaves where they most often hide.
What to look for any minuscule holes/piercings on the leaf, often appearing with a yellow or brown ring or brown spots around the puncture marks.
If anything is sucking the sap from the leaves, they will curl in an effort to preserve moisture content.
Most household plant pests are so small that they are invisible to the eye. The good news is that pest problems on Monstera plants have an easy fix. Hose the leaves and wipe the leaf surface.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.