Monstera leaves browning: what is the problem?

When something is wrong with your Monstera, the first sign that something is wrong will usually be when something is wrong with the leaves. How the leaves change can be a big indicator of what the problem is and one of the most common changes you will encounter is Monstera leaves turning brown. In this guide we will go through everything that can cause Monstera leaves to go brown and how to fix them. 

Overwatering

The line between under and over watering a Monstera is a thin one and it can be easy to underwater this tropical houseplant. Too much water in the soil can lead to root rot which will deprive the plant of the moisture and nutrients that it needs to to survive. As these nutrients are cut off, the cells in the foliage will begin to die and the leaves will start to brown from the edges. 

To fix an overwatered Monstera, the first step to take is to make sure that the soil and the pot have enough drainage. This means making sure that the bottom of the pot has enough holes in it to allow any excess water to drain out. Secondly, you should make sure that the soil has enough aeration to actually allow water to pass through it. This can be done by adding sand or bark to the soil which breaks it up. 

The main reason that soil becomes too wet is because houseplant owners tend not to adjust their watering schedule to the plants needs. As the year goes on and the temperatures change so will the needs of your plant. Make sure you are always checking the moisture levels in the top two inches of soil and watering only when they are dry. 

Sunburned leaves

Monstera plants like bright, but indirect sunlight. This means that the room your plant is in should be bright, but that your plant is not directly opposite a window. When a Monstera is kept in strong, direct light it has the effect of a magnifying glass on paper. The leaves will burn and over time this will kill the chlorophyll in the foliage, causing it to go brown.  If you find your Monstera leaves beginning to burn you need to either move the plant away from its location or cover the window with a blind or sticker that filters the light. 

Too little light

Too little light will mean that your Monstera doesn’t have enough light to sustain itself. When this happens the plant will run out of energy and the leaves will start to brown. This browning will start at the edge of the leaves and slowly spread across it, causing the leaf to droop and eventually die. 

The key to sorting out this issue is to make sure your plant gets more exposure to sunlight. The easiest way to do this is to move your plant to a location that is brighter. If this isn’t possible, consider buying a grow light to put near your plant to supplement the energy it needs. 

Low humidity

Low humidity causes brown spots on a Monstera leaf because unlike other plant species, it takes in a lot of its water through the leaves. When there isn’t enough moisture in the air around the plant it will dry out and turn brown. 

A leaf that has gone brown due to low humidity will also have a papery texture. The brown area will start at the tip of the leaf and run down the edges until the leaf wilts and dies. Fixing this is simple and can be done by regularly misting the leaves, putting your plant on a pebble or water tray or near to a humidifier. 

Over fertilisation 

Over-fertilising your Monstera can cause the leaves to turn brown. These spots will be a black and brown colour and will appear all over the leaf. This browning is caused when the fertiliser in the soil burns the roots and kills them, stopping them from absorbing any water or nutrients from the soil. 

To fix this you should first wash your soil out by watering it with a lot of water over a few days to filter out the buildup of toxic chemicals. You need to make sure the pot is well-draining and that the soil is not left too wet or you will end up overwatering your Monstera. Avoid fertilising your Monstera for a few months after this. In some cases you should consider repotting your Monstera. 

Transplant shock

Monstera plants will get stressed when moved or repotted into a new pot. This is sometimes unavoidable as you will need to repot your Monstera every two years. When you do this the plant will stop growing and the leaves will droop and brown. The only way to fix this is to wait and allow the plant to recover. You can help this happen by watering the plant well to help it establish a new root system. 

Diseases

A common symptom of many plant diseases is a discolouration of the foliage.  Here are some diseases that affect Monstera plants and how to deal with them: 

Eyespot disease - Spilocaea oleagina or eyespot disease is a fungal infection that infects the leaves, creating hairy brown spots that will spread across the whole thing. The spots will be an uneven shape that gets darker towards the centre. This is usually caused by too much moisture in the soil, and can be fixed by applying a fungicide to the plant and altering your plants drainage or watering schedule to compensate

Anthracnose -  another fungal disease, anthracnose develops in existing wounds in your plants foliage. Monstera are most at risk of this condition when the leaves are splitting. You can determine this fungus from others by  the colour of the spots it creates. A wound in the leaf will first turn yellow and then brown. The only way to fix this condition is to remove the infected leaf and apply a fungicide to the rest of the plant.