Why Does My Monstera Have Brown Spots? (And How to Fix It)


Monstera Leaves showing brown spots

Have you been wondering why your monstera has recently developed brown spots on its lavish leaves? Such a turn-off, right? 

To tell you honestly, these spots don’t just appear at random. There are reasons behind why they’re showing now, reasons we need to know, understand, and find solutions to before it’s too late.

Monstera brown spots can either be caused by excesses and/or deficiencies in certain factors. These factors include light, temperature and humidity, fertilizer, and water including its quality. It can also be caused by insects and those that cause diseases like leaf spot and rust.

To give you detailed information on how these factors lead to the development of ugly brown spots on leaves, you have to dig a little deeper. Keep reading and make sure to seriously take notes.

How to Identify Monstera Brown Spots?

Identifying brown spots on monstera can be a tricky job. It’s easy to mistake these spots to something that’s an ordinary part of the leaf’s aging process.

So, I’ve come up with a simple guide to know exactly if your monstera is suffering from brown spots.

How do they look?

The first thing in identifying brown spots is to be familiar with how they look when you see them on the leaves.

Dark brown to black is the usual color of these spots. At times, they may also appear tan or reddish with yellow rings.

Some spots look rounded while others are irregular in shape. Regardless of their shape, they are called spots.

The size is either large or small depending on the nature of the damage it brings on the surface of the leaves.

Monstera leaves with brown pots may also appear necrotic. So, don’t be surprised when you even see them falling off from its main body or growing small leaves than usual. It indicates how heavy the infection is.

What portions of the plant are infected?

Brown spots are usually located at the lower canopy of the monstera. Areas that are heavily shaded are more susceptible to developing brown spots.

Either the upper or lower surfaces of the leaves can have brown spots. Sometimes, both portions have it. It depends on what factor causes the infection.

What Causes Brown Spots on Monstera Leaves?

The appearance of monstera leaves will speak volumes about the physiological problems happening internally.

Brown spots can be a direct expression of a certain problem of this popular houseplant. Other times, it is just a secondary expression of something else.

In here, you’ve got to learn how to carefully identify which factor leads to brown spots of your monstera leaves. To understand clearly, let’s consider the following items below:

Excess Light Leading to Scorching

Have you experienced getting too much exposure to sunlight that your skin turned tan and is almost hurting?

The same thing happens when leaves are overly exposed to light. Light has ultraviolet wavelengths that are harmful to plants when exposure is prolonged.

Plant cells have the tendency to burn when light is too much. The result is large brown spots scattered on the surface of the leaves.

The size of scorching depends upon the extent of damaged cells inside.

There are two factors that lead to scorching. One is excessive light intensity. The other is extended exposure to it.

Temperature and Humidity

Temperature may cause brown spots on the leaves in two ways. If it’s too hot and dry, the monstera may suffer from heat stress which leads the plant to wilt. Leaves start showing brown spots until it gets totally brown and crisp.

When it’s too cold, the monstera leaves may develop chill spots as a result of contact with cold drafts or windows. These spots would look brown after.

Humidity, on the other hand, works as an agent for pathogen reproduction especially when it’s relatively high.

These organisms thrive in a moist environment. Pathogens like fungi are the main contributors to mapping brown spots on the leaves.

Pest Infestation

Pests do love munching on the leaves, sucking juices from their tissues, and making them their food.

Unfortunately, they create wounds that look like brown spots. When left without intervention, they can create great damage to the plant.

Insects like mealy bugs, spider mites, thrips, gnats, and scales are the common enemy of a monstera.

Some of them even poison the plant. The moment you see brown spots on the leaves, these pests might be the culprit behind.

Source: University of Connecticut, College of Agriculture, Health and Natural Resources

Leaf Spot Diseases

Fungi, bacteria, or other pathogens can be the possible reason for the leaf spot disease of a monstera.

Plants normally get them from air or water splashed on the leaves during watering. This disease appears on leaves as spots in varying sizes.

When spores are carried off and have settled on the leaves, they start reproducing.

A susceptible environment hastens their multiplication. Leaf spots will start showing after one to two weeks of infection.

Source: Clemson University, College of Agriculture, Forestry and Life Sciences

Rust

Rust is an infection caused by fungi and it’s very common in ornamental plants like monstera.

From the name itself, this infection creates rusty color on the surface and underside of the leaves. At first glance, the leaves would appear chlorotic but it’s not.

These rust fungi spread on the leaves by producing spores that have powdery texture.

They create lesions on the various parts of the leaves. Sometimes, these lesions combine together creating large brown spots.

Fertilizer Problems

Adding fertilizer is totally okay to keep the monstera plant lush and healthy. Your plant will surely enjoy the added nutrients in the soil. But, anything that goes beyond what it needs is going to hurt the plant.

Fast-release fertilizers, once added in excess, will cause the burning of cells due to salt build-up.

Too much salt available near the roots will lead to osmotic stress, meaning water in the cell will leave in a rapid motion. Cells are then left shrinking and dying.

It acts pretty fast so, in only just one to two days, you’ll notice the brown spots appearing on the leaves.

If not acted on immediately, it can lead to the sudden death of a monstera. So, you have to be very careful in doing fertilizer application.

Incorrect Watering

Knowing how to sufficiently provide water to plants is a skill every plant owner has to acquire.

The tricky part is that plants differ in the way they utilize water. So, you have to understand how much water it needs and when it needs it.

Root rot is the result of overwatering your monstera. Read this article to know how to save overwatered monstera.

Nutrients and water transport are then compromised because of this. The next thing you know is that its leaves start showing brown spots until it’s all over the plant.

Deficiency in water can also lead to scorching of leaves especially on its margins. When water isn’t enough, the plant suffers from drought stress.

This is where the cells lose their turgidity or swollen appearance because there’s not enough water coming in.

Water Quality

We’ve mentioned earlier that some pathogens can be transferred to another plant through irrigation.

If you’ve used water that’s previously contaminated with pathogens, they can start infecting the monstera.

Another thing is when the water used has high salt content; the plant will have hard time absorbing water from the soil.

This is another source of stress for the plant. Excessively saline water will lead the plant cells to shrink and die.

Outwardly, you’ll observe the leaves developing red to brown spots. Monstera has a low tolerance for salty soils.

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How Do You Treat Brown Spots on Monstera?

Although brown spots on leaves aren’t much of a problem, you’ve got to pay close attention once you notice them growing and expanding.

Any treatment has to be done as early as possible to avoid extreme damages. There are instances that monsters will face death if it’s left untreated.

Relocate the Plant

Monstera prefers indirect light. If it has contact with strong, direct light for many hours, you have to find a new location for it. If necessary, put a shade around it as protection.

You may also alter the light condition in your home if you’re using an artificial light source.

Avoid Exposure Extreme Temperatures and Humidity

Make sure to put it away from a fireplace where there’s too much heat coming out of a window that gets extremely hot or cold depending on the weather.

Remove the plant away from any source of cold drafts such as air conditioners or fans.

You just have to be mindful of the existing condition inside your room. Anticipate how these extremes will affect your plant’s health in general.

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Manage the Pests Before It Turns Your Plant Down

Pests multiply very fast and in just a matter of days, it can cause major damage to the plant.

If it’s manageable, manual removal of pests will do. Make sure to pluck out severely damaged leaves as well.

If the damage is beyond control, use a pesticide that’s appropriate to eliminate the unwanted organisms.

Just be careful in applying these chemicals to avoid harm. You may also opt for organic and DIY solutions at home to save money.

Remove Infected Plants and Put them Away from the Others

The last thing we want is to have them spread over the disease to other host plants. Isolate the infected monstera when you treat them.

Bring them back only when it’s well again. Dispose of the infected parts properly to avoid cross-contamination.

You have the option to burn these leaves or treat them with fungicide first before you bury them somewhere far away from any garden. Clean the tools you’ve used.

Leach Off Excess Fertilizers

If the brown spots are caused by the application of too much fertilizer, you can use water to leach the salts off the soil. These salts are water-soluble so it’s not that hard.

Pour in an ample amount of water on the soil until it drips off the pot. You can do this several times. Just make sure the water drains off completely out of the pot to avoid root rot.

Moderate Your Water Application

If water is the problem, then its water you control. Overwatered monstera should be allowed to dry off first by exposing them to moderate sunlight. This is just to help the water evaporate faster. Repot the plant if necessary.

Underwatered monstera should be given enough water immediately until the leaves start looking full and vibrant. Drip irrigation is the key to make sure that water is reaching down the bottom of the soil.

How To Prevent Brown Spots on Monstera Leaves?

 brown spots on monstera leaves

As a living organism, the different stresses plants experience affect them. These stresses can be naturally induced or not.

In order to prevent brown spots from tarnishing the leaves of monstera, you have to avoid or at least lessen these stresses.

Less stress leads to a healthier plant. So, here are a few preventive measures in order to avoid brown spots on your monstera leaves.

Give Sufficient Indirect Light

It’s an indoor plant so it thrives well in an environment as such. Do not allow the monstera to be exposed to direct sunlight. Or, if you do, make sure it’s not exposed too long.

This plant can utilize indirect light for photosynthesis so there’s no point in exposing them to harsh conditions outside. It will just stress out the plant.

Prepare for Hot Days and Cold Days

If you have a working air condition that you turn on when days are hot, your monstera will surely benefit from it.

The added coolness will prevent the leaves from developing brown spots caused by heat stress.

Insulation should be ready as well in anticipation of the winter season. Finding a safe location is another thing that will save the monstera from having chill spots.

Always Be on the Lookout for Pests

Never take a single pest lightly. They often work in a subtle way, growing rapidly in just a day. Before you know it, these pests may have infected the leaves heavily.

The moment you see foreign organisms roaming around your plant, remove it. Some pests can be taken care of just by directly spraying water on them.

Others can be manually removed using your fingers. Be careful to kill and dispose of them immediately.

Cut Off Infected Leaves As Soon as Possible

This is especially applicable if the cause of brown spots is due to diseases and pests.

Removing infected leaves will help mitigate the spread of infection. Don’t worry because your monstera will surely grow new ones.

It’s better to get rid of the infected parts as soon as possible than risking the entire plant of heavier infection.

Regularly Water Your Monstera

Monstera is a huge indoor plant so it would need more water supply. Water the plant 2 to 3 times a week or until the soil is at least 50 to 70% dry. This, of course, depends on the season.

Always check if the water drains off completely. Use a hose, as much as possible, to make sure the pot is deeply irrigated. Water all around inside the pot to provide uniform moisture on the soil.

Always Start with a Healthy Soil

When potting, choose a sterilized soil to make sure pathogens have been killed. This will lessen the possibility of transferring diseases to your monstera. Pathogens can live in the soil for a long time.

A well-amended soil that’s rich in organic matter will keep the plant strong and healthy. Nutrients that are made available in the soil in sufficient amounts will lessen fertilizer application. Slow-release fertilizers are also preferred.

Use Clean Water

It’s very easy to transfer fungi and bacteria through the water. If you’re using water that’s not clean, it’s possible to inadvertently transfer these harmful organisms to your plant causing further harm.

Tap water is enough but if you have the chance to catch rainwater, it would be even better. Rainwater is free from chemicals and other treatments so the plants love them.

Notice that plants outside after they’re drenched with rainwater will instantly look vibrant and good.

Avoid Excessive Moisture

Misting can help the plant on hot days but not when relative humidity is high. A moist environment is friendly to pathogens. You’re giving them the chance to multiply.

Allow excess moisture to evaporate off the plant by applying water only in the morning and not in the evening. That way, there’s enough time to lose the water throughout the day.

Can You Maintain Healthy Monstera Leaves?

Taking care of monstera is extra challenging because this indoor plant is normally huge. Seeing brown spots on its leaves will certainly bring panic. You may be having doubts now if you can make your monstera a success story.

But definitely, with proper knowledge and understanding of the factors above, you’ll surely figure out how to manage them properly.

The goal is to create a favorable environment for the plant to enjoy. Minimize the stress and your monstera will surely do well. Can you do that?

Arifur Rahman

I'm the owner of gardenforindoor.com. After completing my bachelor of science in agriculture, I'm serving as a civil service officer at the Department of Agricultural Extension, Bangladesh. I started Garden For Indoor to make your indoor gardening journey easy and enjoyable.

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