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Causes of Monstera Leaves Curling and How to Fix

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Monstera and Philodendron are the two most popular aroids (of the Araceae family), and while they’re easy to care for, some challenges may present themselves.

Monstera leaves are particularly attractive with their fenestration and glossy look, but monstera leaves curling is a sign that something is amiss. Monstera leaves curling is usually a sign of over or underwatering, low humidity, heat stress or general distress.

Top 10 Reasons for Monstera Leaves Curling

There are several reasons for monstera leaves curling, and some causes of curling leaves are less easy to detect. This article explores all the possible reasons for monstera curling leaves and how to remedy each leaf curling cause. Below is a list of ten potential causes for monstera leaves curling:

  1. Overwatering
  2. Underwatering
  3. Root Rot
  4. Excess Fertilizer
  5. Temperature Stress
  6. Humidity Levels
  7. Fungal Disease or Insect Infestation
  8. New Monstera Leaf Emergence
  9. Root Ball Compaction
  10. Light Levels

Monstera Plant Leaf Development

For the young Monstera deliciosa living in the shade of the rainforest’s canopy, either on a tree (epiphyte) or the forest floor (nomadic vine), access to light and water are the primary concerns. Evolution has provided several ways for the young Monstera deliciosa to maximize water and light availability.

Skototropism

Most plants grow toward the light, a trait known as phototropism. Some plants, however, have negative phototropism, the trait of growing away from light. Most epiphytes (plants that live in trees) have a form of negative phototropism called skototropism.

Instead of growing toward the light, skototropic plants grow towards the darkest shape on the horizon, hoping to find a tree to climb.

Heteroblastism

Heteroblasty is the significant changes in the form and functions of plant parts as they grow. While all plants develop in shape and form as they grow, monstera leaves are unique in their total metamorphosis from juvenile monstera leaves to fenestrated adult leaves.

Fenestration

Young Monstera plants grow towards the darkest space on the horizon as evolution has taught them that the dark shape represents a tree. Evolution has taught them that trees offer height and access to better light.

Young Monstera, known as “shingle plants,” have smaller monstera leaves without lobes or holes (fenestration). The young monstera leaves develop closely, overlapping one another up the tree trunk. The Monstera leaves only split and fenestrate when they become older and are exposed to more light.

As far as monstera leaf curling goes, it is natural for the young monstera’s leaves to be curled as it matures. The absence of lobes or fenestration gives the young monstera’s leaves to capacity to maximize sun utilization for photosynthesis. 

As the monstera’s leaves mature, light is less of an issue, but water is. The fenestration allows water to be channeled to the aerial roots and the base of the plant where it’s needed. 

You can boost leaf-splitting and fenestration of your Swiss cheese plant by exposing younger monstera plants to brighter light, but you should guard against direct sunlight damage. 

10 Causes and Cures of Leaf Curl in Monstera Plants

1. Overwatering

Overwatering is one of the main causes of monstera leaves curling or chlorosis (leaf yellowing). Monstera leaves curl when they lose turgidity, a pressure loss in the cells caused by reduced water supply. This loss of water supply can be because of drought or when fungi compromise the water supply.

Loss of turgidity can be either due to drought or plant disease. Plants become flaccid when the pressure in the plant cell drop. Turgor is the distension of a plant cell’s protoplasmic layer and wall by the fluid contents. The fluid content is regulated by water availability and osmosis. A drop in internal water pressure cause leaves to curl. 

In most situations, monstera leaves curl because they’ve run out of available water or access. Water constantly flows bidirectionally in plants, upwards with the xylem and towards the roots with the phloem. This is known as the plant’s vascular system. 

Xylem moves water from the roots, up through the stems, and out to the monstera leaves. Once water enters the leaves, most of the water (typically 95% or more) escapes into the air through tiny holes in the leaves called stomata – a process called transpiration. 

The phloem moves food components throughout the plant, particularly dissolved sugars, amino acids, and lipids produced during photosynthesis.

Consider a Monstera that is 40 feet tall, and its upper leaves require a constant water supply to keep the leaves cool and erect. A vacuum is created as water transpires through the leaves and into the atmosphere. 

Think of the xylem as internal pipes transporting water to every plant area. They are very good at gathering water molecules into lengthy chains and dragging them up through capillary action and out to the plant’s leaves, where the vacuum was created.

Causes of Monstera Leaves Curling when Overwatered

Overwatering is a risk to all your plants as it causes fungi to damage your plant’s vascular system, preventing water from reaching the leaves to curl. The symptoms for overwatered monstera and underwatered plants are very similar.

The only way to know if your monstera leaves are curling because of over or underwatering is to check for root rot – a definite indicator of overwatering and the source of the fungi damaging your plant’s plumbing.

Chlorinated Water

Chlorinated tap water is detrimental to most plants. Some tap water also contains fluoride. Purchased filter water, by regulation, needs to go through several tests before being allowed on the shelves and is quite safe for plants.

Placing a filter on your tap water doesn’t always remove chlorine. Rather take tap water and allow it to stand in an open container for 24 hours to allow the chlorine and fluoride to dissipate. It is safe to use the next day. Make it a habit and common practice not to use tap water directly from the faucet.

A solution to Overwatering

Overwatering generally is caused by random acts of kindness – giving your plant a drink when you see leaves curling. A better way is to follow a schedule and stick to it, but the best way is to test the soil’s moisture levels physically.

Moisture levels can be tested using a moisture meter or by sticking your finger in the plant pot and checking it. If you use a moisture meter, consider wiping it with rubbing alcohol between each test to avoid spreading any fungal disease.

A key component to avoiding overwatered monstera is your soil mix. A balance between organic and inert materials (perlite, vermiculite, pumice,  gravel, etc.) helps soil drain better and prevents water accumulation.

2. Underwatering

The water pressure on plant cells causes turgidity, maintaining the plant’s posture – preventing leaves from curling. Plants rely on their turgidity to keep them sturdy and erect. The water chains in the xylem get thinner and thinner if the amount of water in a plant’s soil gets too low.

In effect, the plant loses water more quickly than it is taking in, causing the leaves to curl. This frequently occurs due to low soil moisture, but there are additional reasons.

When it is warm or hot outside, plants lose more water through transpiration, which can cause them to wilt as their water needs exceed the supply.

In the case of an underwatered Monstera, the water supply is interrupted, and no moisture is available to prevent monstera leaves from curling. While it’s a good practice to leave the top soil dry before watering again, don’t extend the gap between watering too long.

Overwatering is the main reason why potted plants die. When surrounded by water, roots cannot absorb oxygen – remember, they require water and oxygen just like humans do.

Underwatering Solution

The general rule is to only water when necessary. To decide when to water, one may utilize the following techniques:

·        Touch the soil: The most accurate test for soil moisture is to feel how dry the potting soil feels. If the mixture is dry at your fingertip after inserting your finger up to the second digit, it needs water. Check at least to a depth of a third of the pot.

·        Tap the pot: When potting mix in a clay pot starts to dry up, it shrinks away from its sides. Use a stick or your knuckles to tap the pot’s side. Water is required if the sound is hollow; if the sound is dull, the soil is moist.

·        Estimate weight: It’s easy to see a weight reduction as potting mixtures dry up.

·        Assess soil color: As potting combinations dry, their color will shift from dark to lighter.

When watering is necessary, water deeply. Apply water until the bottom of the pot is completely submerged. Thorough watering removes salt buildup and ensures the entire plant root system gets enough water. Empty the tray, and don’t let the pot sit in the accumulated water. Make sure that every drainage hole allows the pot to drain.

3. Root Rot

The third most common cause of monstera curling leaves is root rot. A healthy root system is essential for a healthy plant. I will deal with repotting later, but it’s important that the monstera plant’s root ball is given as much attention as the visible leaves.

Solution

The best solution for most ailments is prevention. The most cost-effective way of dealing with established root rot is to discard the plant. If you decide to nurture it back to life, you will need to repot the plant, removing as much of the rotten roots as possible. 

Root rot fungi prefer wet soil conditions, and Pythium, for instance, produces spores that survive and thrive in the soil or plant debris. Avoid chemical fungicides, as these have a domino effect on your houseplant ecosystem and are expensive.

Most importantly, reduce watering rates.

4. Excess Fertilizer

Your monstera isn’t a heavy feeder. All the aroids only need a very diluted application of a balanced fertilizer to remain healthy. An over-fertilized monstera plant is susceptible to various ailments, including monstera leaf curl.

When making a soil mix for your pot plants, ensure that at least 25% of the mix is compost, 25% coconut coir and 50% inert aggregates to ensure healthy drainage.

This inclusion of compost is a way to introduce beneficial microbes that help with nutrient availability, even further reducing the need for synthetic fertilizer.

While a very diluted fertilizer applied regularly will boost the health of your monstera leaves, highly concentrated applications given less often make monstera leaf curl.

How to Fix Over Fertilization

Over-fertilization can be remedied by flushing the pot with water and removing excess fertilizer. If this doesn’t help, consider repotting fresh soil with compost for added beneficial microbes.

5. Temperature Stress and Solutions

Heat stress, high temperatures and low humidity will cause monstera leaf curl. Both high and low temperatures, as well as sudden temperature fluctuation, will cause leaves to curl. Avoid placing your monstera in front of open windows in cold drafts or front of air conditioning vents.

Heat stress followed by cold drafts can cause monstera’s leaves to curl. Plants need to acclimatize to their surrounding, and an incremental shift from a cooler to a warmer temperature will help prevent the monstera leaves from curling. 

Crispy leaf tips can be a symptom of dehydration or heat stress as plant leaves lose moisture faster than the xylem can replenish it. In heat waves, it is important that the relative humidity is increased, creating a protective hydration cocoon around the plant to slow the 

6. Humidity Levels

Monstera leaves curl in low humidity as the transpiration rate accelerates to keep the plant cool. Rainforest aroids, like the Monstera deliciosa, are used to high humidity levels of around 60% and higher. They are unable to manage low humidity levels below 40%. 

Solution

In high humidity, plant leaves form a protective vapor barrier with the water vapor released around the leaves. You can increase humidity levels in your home to benefit your Monstera and your other houseplants.

  • Transpiring plants are grouped to create a humid microclimate.
  • Use a hydrated pebble tray under your Monstera to ensure that the pot’s base sits just above the water level. The evaporating water helps boost humidity.
  • Using a humidifier is the easiest and fastest way to regulate humidity around plants. Most models allow you to maintain your desired relative humidity and are a fantastic option for houseplants.  

7. Fungal Disease or Insect Infestation

Diseases

One of the advantages of the monstera houseplant is its resilience to diseases, most of which are easily managed by healthy cultural practices like avoiding overwatering and over-fertilization. 

You can protect the health of your monstera leaf growth by watering the base of the plant. While many suggest misting leaves, I prefer avoiding the practice as it can promote the spread of pathogens. If you do mist your leaves, ensure you do it before midday, giving the plant’s leaves enough time to dry before sunset.

Insect Infestation

Insects that may inflict damage on your monstera leaves include spider mites, thrips, and aphids, all sap-sucking insects. Curling leaves come from these insects sucking the nutrient-rich sap from the leaves.

Because all these insects are so small, you’ll need to be vigilant to spot them and take action before too much harm is done. Look for them on the entire leaf, both above and below.

Solutions

I always opt for a nonchemical or organic approach to getting rid of insects in houseplants. Soft-bodied bugs like thrips and spider mites respond well to dishwashing liquid soap, rubbing alcohol, and neem oil. If there is a severe infestation, the chemical approach should be used

8. New Monstera Leaf Emergence

When a juvenile monstera leaf emerges, it is natural for them to curl. In this instance, curling leaves are part of leaf growth and development.

9. Root Bound

Monstera leaves curl when their roots become encased and have limited access to water because of it. Repotting your Monstera plant in fresh potting soil helps prevent all kinds of challenges to plant health.

Choose a slightly bigger plant pot with enough drainage holes when repotting your root-bound monstera. A healthy root system depends on potting soil that retains moisture while draining excess water well. While roots should be somewhat root-bound, excessive root compaction causes monstera leaves to curl.

Solution

A compromised root system is one of the main causes of underperforming monstera plants. As root health is directly related to the soil’s efficacy at managing moisture and oxygen levels, let’s explore soil options.

Ideally, potting soil should be 50% inert materials like perlite, vermiculite, pumice, gravel, expanded shale, or turface.

The remaining 50% should be a mix of organic materials like orchid bark, coconut coir, peat moss, and compost. The inert material help improves drainage and aeration, and the organic material improves water retention.

The addition of compost introduces beneficial microbes to improve plant resilience and cation exchange capacity, the soil’s ability to manage nutrients. Leaves curling and stunted growth will significantly reduce if the root system is healthy. 

10. Light Levels

Because this tropical plant lives under the canopy of rainforests, it prefers indirect light. Direct sunlight can make monstera leaves curl. Their dark green leaves are amply efficient at capturing indirect light.

Monstera Plant Light Needs

Most aroids need plenty of indirect light, especially for maintaining variegation. Plants like the Monstera standleyana are medium-light plants that need 15 watts per square foot.

In the Northern hemisphere, medium indirect light (100 – 500 FC) indoors will be provided by the sun entering an east or west-facing window. The sun entering south-facing or west-facing windows will provide high light (500 – 1000 FC) indoors.

In Closing

As we’ve seen, the Monstera plant’s leaves curling is a sign that they’re in distress. Fortunately, we now know what to do to help our beautiful aroid.

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