Why Are My Monstera Leaves Turning Brown? | How to Fix It

Commonly known as the Swiss cheese plant, Monstera is a tropical, vining plant that comes from South America and is commonly grown as an ornamental houseplant for its striking foliage. 

This plant has huge, green leaves that are deeply lobed and develop holes as they mature, hence the name Swiss-cheese plant. 

Monstera is hardy and relatively easy to grow. Nonetheless, browning of the leaves can still occur and this is usually a sign that your plant is not happy in its current conditions. 

This article covers the reasons why your Monstera leaves are turning brown and more importantly how to rectify it and prevent future cases. 

Why Do Monstera Leaves Turn Brown?

Monstera are evergreen plants so should retain their lush, green foliage all year long. Therefore, the presence of brown leaves indicates your plant is unhappy and unhealthy.

When brown patches appear on leaves, known as necrosis, this means the tissues are dying or are already dead. They often feel dry and crispy to the touch. 

Brown leaves can occur for a number of reasons including underwatering, overwatering, scorching, pest infestations, diseases, lack of humidity, nutrient deficiencies or salt buildup in the soil. 

The green colour of healthy leaves is due to the presence of a pigment called chlorophyll. Without sufficient chlorophyll, leaves cannot photosynthesize and will begin to turn yellow and then brown. This discolouration is known as chlorosis.

Causes of Monstera Leaves Turning Brown

Browning leaves usually occur alongside other symptoms that – once identified – will help you to diagnose the root cause. Once you have found the problem, you will be able to quickly treat it and prevent future occurrences. 

The following causes are some of the most common reasons for your Monstera leaves turning brown. 

Underwatering

Light brown and crispy edges on your Monstera leaves are a sign it’s not receiving enough water. This usually occurs in combination with dry soil and dropping leaves. 

Dry soil limits the amount of water your plant can uptake and inhibits nutrient absorption, causing browning.

To remedy the problem, water your plant immediately. Monstera prefers moist soil and moderate watering. Give your plant water once the top few inches of soil feel dry to the touch. 

Extra watering will be required during very hot months and significantly less watering will be required when your plant is dormant during the winter. 

Overwatering

As well as underwatering, overwatering can cause your Monstera leaves to turn brown. Dark brown spots or patches on the leaves alongside saturated soil suggest your plant is receiving too much water. 

Waterlogged soil deprives the roots of oxygen, preventing them from absorbing essential nutrients. Waterlogging can also lead to root rot which can ultimately kill your plant. 

I find the best way to rectify this is to repot your Monstera in fresh soil. Ensure the soil is porous and well-draining. Additionally, check for drainage holes in your container. They need to be a good size to allow excess water can drain out. 

Only water your plant when the first 2 inches of topsoil are dry to the touch. 

Water Quality 

Tap water contains a variety of chemicals including chlorine and fluoride, with hard water being particularly harmful to Monstera. These chemicals can damage your plant by killing essential soil microbes and inhibiting nutrient absorption. 

Symptoms of poor water quality include chlorosis, brown tips and crispy leaves. It’s best to water your plant with rainwater or distilled/filtered room-temperature water. 

Sunburn

Monstera favour bright but indirect light. Prolonged periods of harsh, direct sunlight can scorch the leaves. Sunburned leaves have black and brown patches that cover the majority of the surface. This is the result of the sun killing the chlorophyll in the leaves. 

If your Monstera leaves look like they are beginning to burn, immediately move your plant to a new location. Place it somewhere it will receive filtered sunlight. 

Too Little Light

A Monstera that is not receiving enough sunlight will not be able to photosynthesize. As a result, the leaves may suffer from chlorosis and the edges will begin to turn brown. If left untreated, the browning will spread to the rest of the leaf, causing it to droop and die.

To rectify this, move your Monstera to a location where it receives more sunlight. Make sure the light is bright but indirect. You can also buy artificial lighting to help provide it with the energy it needs. 

Low Humidity

Native to Central America, Monstera is used in tropical climates that have high humidity. Dry air will pull moisture from the leaves, causing them to develop brown spots, starting at the tips and running down the margins. The leaves will also have a crispy texture. 

To increase the moisture levels in the air, you can regularly mist your Monstera leaves. You can also use a humidifier. ALternatively, place your plant in a pebble tray or position it near to other tropical houseplants.  

Nutrient Deficiencies

Monstera takes up different nutrients from the soil in different ratios. Browning of leaves is often caused by deficiencies in potassium and phosphorous. 

A potassium deficiency manifests itself as leaves that are yellow and brown at the tips, margins and between the veins. It affects older leaves first and they may eventually drop. Younger leaves will also see brown spots.  

A phosphorous deficiency will see older monstera leaves turning yellow and then developing a dark brown hue with dead patches. If left untreated, the affected leaves will drop. 

If you suspect your Monstera is suffering from a nutrient deficiency, you can run a soil pH test to find out what nutrients are lacking. Use a slow-release fertilizer with an NPK ratio of 3-1-2. Feed your Monstera monthly during the growing season. 

Overfertilizing 

If you have overfertilized your monstera, it will show black and brown spots on the leaves. This browning is the result of the fertilizer in the soil burning and eventually killing the roots. As such, this means they are unable to absorb any water, oxygen, or nutrients. 

To rectify this, remove your Monstera from its soil and wash any excess off with water. Check the roots for any sign of damage and remove those that are brown or back and squishy when touched. 

Replant your monstera in new soil and avoid fertilizing your Monstera for a few months until it has recovered. 

Pests and Diseases 

Like all plants, Monstera is susceptible to numerous pests and diseases, some of which can turn the leaves brown. 

Aphids, thrips and spider mites are tiny, insect pests that suck the sap from Monstera leaves. As they do so, they remove the moisture from the leaves, causing tiny, dry brown spots where they have killed the cells. 

The best way to get rid of these pests is to blast them off with a jet of water, then brush off those that remain and can be seen by the naked eye. Thereafter, treat your Monstera with an insecticide weekly until all traces of the infestation are gone.

While you are treating the affected plant, you should also isolate it from other plants to avoid cross-contamination. 

Eyespot disease is a fungal infection that manifests itself as hairy, brown spots on your Monstera leaves. This is usually caused by overwatering. It can be rectified by treating your Monstera with fungicide and reducing how often you water it. 

Read more about house plants with brown leaves by clicking the link to Why are my Anthurium leaves turning brown?

FAQ Why Are My Monstera Leaves Turning Brown

Why are the new, unfurled leaves on my Monstera black and brown?

This is likely the result of improper soil moisture for a prolonged period, either overly saturated or completely dry. 

Citations

Website | + posts

Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.