Monstera leaves turning black can become a major issue if you cannot care for your plant. Yes, Monstera is one of the easier plants to grow, but it still needs care and attention.
So for those of you who grow the beautiful Monstera, but are hit with this ‘black spots on the leaves’ issue- keep reading.
Below I will address what can cause black spots on your leaves and how to combat this.
Let’s dive in.
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Why it’s important to address black spots on leaves
Monstera grows into a large, beautiful plant. Their Swiss cheese-like leaves have made them a favourite amongst household designers. And this doesn’t surprise me. But black spots hinder massively their attractiveness and appeal.
It is upsetting to grow a baby Monstera to its large, wild maturity and then to see all that hard work put on the line by the appearance of black leaves.
It’s a bit like having black spots on your face or nose. It takes away attraction and makes you look unclean.
Black spots on leaves is a problem you will not want. And more importantly, a problem you can avoid.
Hence, for those who struggle, or even for those who have not had this issue- it is important to understand what can cause black spots and what the solution is to each problem.
What can cause black spots?
Overwatering
Most beginners panic water their plants. They assume plants need more water without checking the soil or researching the plant itself. Monstera is a big plant and this can deceive new planters especially.
With overwatering, the roots of the plant will rot. The Monstera leaves will start turning black and this, will affect the whole plant.
Early signs of overwatering include: the leaves will become yellow and turn black if left unattended. The stem becomes soft and squishy. The soil is moist and this will attract pests, as they prefer moist conditions.
Solution:
If there are signs of overwatering as described above, remove the plant from the pot and check the roots. If the roots are black and rotten, they need to be cut. Only remove the roots and leaves that are affected to prevent spread.
Wash the plant and the pot (make sure it has drainage holes). Add fresh soil to the pot and repot your plant.
Compost is great to add and also helps with drainage. It may be a good option to add 20% cactus compost to your soil mix.
Good Tip!
Healthy roots are slightly brown. Do not cut them off.
Wash the plant pot with water and add fresh soil.
Add perlite, pumice or rocks to help increase drainage. Also, use a pot with drainage holes if you are not already using one.
Underwatering
Underwatering your Monstera can make your leaves turn brown. Eventually, they can turn into black spots as well.
If you suspect underwatering, check the soil. If it is dry, then the plant needs water.
Solution:
Dip in your index finger to check soil moisture. If the soil is dry, then water it.
If the water dries more quickly than normal, for example, in a couple of hours- then there is something wrong. Water should not drain this quickly. A cause of this can be because the plant is root-bound. Plants have no space to hold on to water and this results in the quick expulsion of water from the pot.
If the plant is rootbound, repot into a container the next size up.
Sun burns the leaves
Monstera does like light BUT not like direct sunlight nor overexposure to light. This can scorch the leaves and the colour will turn yellow/ brown.
To note- Monstera can tolerate direct sunlight but for short periods only.
Moreover, plants are grown close to the west or east-facing windows are exposed to more direct sunlight. Hence, if you grow your plant in these directions, there is a higher chance of the leaves having black spots.
Solution:
If you place your Monstera close to the west or east-facing window, the sun is lower at this point and the light is harsher. This may cause the leaves to burn. Hence, keep the plant at least 2 feet away.
Ideally, try to place your Monstera close to a south-facing window. This is bright but indirect sunlight which is perfect for your plant.
If you grow outdoors, place your pot somewhere where there is shade. The porch is a good example as it allows bright sunlight to hit the plant, but without overexposure.
Good Tip!
Rotate your plant pot every couple of days so each part of your plant receives an equal amount of light.
Low humidity
Monstera originates from tropical regions hence, they prefer humid conditions. If the air is dry, the plant leaves will get black spots.
Solution:
If you live somewhere with low humidity, invest in an air humidifier.
A good trick is to place water close to the plant. Once the water evaporates, it will add humidity to the air close to the plant. This should compensate for low humidity levels. This should prevent Monstera leaves turning black.
Poor fertilisation
Both poor fertilisation and over fertilisation can cause black spots. Alternatively, the colour can fade as well. But poor fertilisation is the more common problem- hence read ahead carefully.
Solution:
Fertilise once a month, but not in winter. Monstera goes dormant in winter and offers very little growth. But, if you fertilise religiously during spring and summer, the Monstera can still grow at a slow rate.
Avoid misting as the leaves can trap moisture. This attracts pests and diseases.
Pests
Pests love to feed off plants and can take away the beauty of a leaf if it has chewed half of it off. They also release their droppings on leaves and, over time, this can cause rotting of the plant. This will cause black spots to appear.
Solution:
Wherever there is a plant, there will be pests. Hence, it is logical to add pesticides to the Monstera.
Secondly, always check. Keep a good eye and look out for any signs of insects, damage or even webbing.
However, realistically, it’s difficult to inspect every little ant that crawls up onto the leaves. Hence:
- Keep new plants away from your old plants for a couple of weeks. This is just in case your new plant becomes infected or has pests.
- Always sanitise the equipment you use. Scissors, shears and moss poles are common equipment you may use.
- Spray your Monstera with neem oil or wipe it with rubbing alcohol. Both will cause no harm to the Monstera.
Disease
The primary cause of black spots is bacterial and fungal diseases. They can be easy to identify as most black spots will have a yellow circle outline.
If there is little growth, check the roots. If roots are rotten, mushy and have a foul smell- cut them off. The roots will regrow quickly, so there is no need to be concerned.
Solution:
Diseases thrive in moist conditions. Hence, try to keep your Monstera leaves dry. Remove dust and use neem oil to keep the leaves clean.
Avoid misting as this increases moisture. Hence, if you want to water your plants or fertilise them, it is better to add to soil NOT to the leaves via misting.
If you have any infected leaves, prune them off. Diseases are contagious and not cutting them off can affect other areas of the Monstera.
Difficult to diagnose
I have listed the common reasons that can cause black leaves, but its diagnosis can still be difficult. For example, root rot may be present, but what could have caused it? Root rot can happen when the plant is sunburnt, or because of fungus, or overwatering…
Hence, record your care routine. That way, if something goes wrong, you have a trail to find the root cause of a problem.
Why are new leaves turning black?
Moisture imbalance can cause the blackening of leaves. This decaying of leaves is especially common when there is excess moisture.
We see this when you propagate using the air layering method. If the plastic is around a node too tight, moisture will build up and the roots grown will blacken.
Hence, it is important to control soil moisture, humidity and aeration to prevent moisture imbalance.
Why not check out the post: The Ultimate Guide: Monstera for Beginners for a more detailed guide on how to grow and care for a Monstera.
Should you cut black leaves?
Cut them off. The cause can be because of disease or pests and, if not dealt with, can affect the plant.
Invest in a clean pair of scissors or shears and make sure they are sharp to cut off any dead or infected parts of a plant.
Final Words
Monstera is one of my personal favourites. They are simple to grow and require little attention to grow into elegant, monstrous plants. But, care is still vital. Without the proper care, Monstera leaves turning black can become prominent.
Hence, it is important to understand what causes black spots on leaves. Common reasons include overwatering, underwatering, low humidity, pests and diseases.
But even with the appearance of black spots, do not become disheartened. The Monstera still has plenty of life left in it. Prune off the affected roots and leaves, repot and let it grow.
Good luck!
