10 Reasons Your Monstera Plant Has Brown Spots

Monsteras are beloved houseplants, an impressive genus of interesting leaves and amazing patterns. As they are appreciated for their foliage, it can be distressing when that foliage begins to discolor and die off, indicating a serious growth problem.

So, if your monstera has started showing brown spots on the leaves of the plant, then it’s common to wonder what’s happening with your plant.

There are many reasons why your monstera may develop brown spots, from incorrect care to environmental conditions and pests and diseases. Take a look at these common issues to decide which is most likely and use the fix to resolve the issue.

Too Much Sun

In their native habitats, monsteras climb up trees, shaded from the leaves of taller trees above. They typically receive dappled or filtered sunlight from above, enough for photosynthesis and further growth.

When grown indoors, the closest match to these native conditions is known as bright indirect light. These are areas close to bright windows but out of the path of any direct sun’s rays. As they are accustomed to shady conditions, any intense direct sunlight can lead to growth problems, including brown spots.

A sunburned monstera will develop brown patches on the leaves closest to the light source. These will be irregular and concentrated in the areas where the sun hit the leaves directly.

The leaves may also lose their green color, turning a ghostly white. The stems may begin to turn away from the light source to protect the plant from further damage.

The fix for this issue is simple – move the plant to a shadier spot. Simply shifting it out of the way of the direct light but still close to the window will help maintain growth. Prune any leaves with large brown spots to encourage new and healthy growth.

Overwatering

Monsteras are hemiepiphytes, growing with the help of both soil and aerial roots. The plants need plenty of aeration and good drainage around the roots to improve oxygen movement and prevent fungal growth. If the roots struggle, the rest of the plant will too.

If you add moisture to the soil when it is still wet, the roots won’t be able to breathe. This excess moisture leads to fungal growth that can begin to attack the roots – a condition known as root rot. This can cause brown or black spots to develop on the leaves and stems as the rot spreads throughout the plant.

However, root rot in monsteras is not only caused by overwatering. It could also be the result of a lack of drainage in the pot or the soil. Extremely high humidity or overhead watering can also cause the same brown sunken spots if moisture is allowed to settle in parts of the plant.

Prevent root rot by only watering when the top layer of soil has completely dried out. If you suspect root rot, repot the monstera, trimming the affected roots to prevent further spread. Also avoid overhead watering and keep the leaves dry to stop more spots from forming.

Tap Water

The next cause is also related to watering. But, instead of how much water the monstera gets, the root of the problem relates to what water you are using.

Monsteras and other tropical houseplants are sensitive to the chemicals in some tap water, particularly in dense cities. The chemicals used to clean the water can build up in the soil, causing the roots to ‘burn’ in the same way they would when overfertilized.

Root damage can cause damage further up on the plant. Leaves may begin to develop brown patches that become crispy and die off. If you cannot think of any other potential causes related to recent care, they are likely the result of prolonged use of tap water.

To fix the issue, start by pruning majorly affected leaves. Then flush the soil by rinsing with filtered or distilled water to prevent more build-up. Make sure you change the water you use, or alternate watering with tap water and filtered or rainwater to keep the soil healthy.

Too Much Fertilizer

Monsteras grow best when given the right amount of fertilizer once every few weeks during spring and summer. If your monstera is growing slower than usual, you may want to counteract the problem by fertilizing. Unfortunately, when used incorrectly, you will likely notice patches of brown developing on the leaves.

This happens for the same reason as the use of tap water – build-up of salts in the soil. These salts damage the roots, limiting their ability to function and displaying signs of a problem above the soil too.

Overfertilized monsteras need plenty of time to recover and return to normal growth. Flush the soil with filtered water until it runs clear and avoid fertilizing for several months. Overfertilizing is tougher to fix than under-fertilizing, so err on the side of caution.

Lack of Humidity

Temperature and humidity are vital conditions to consider if you want to keep a monstera happy. Temperature is usually covered by keeping the plant indoors as they tend to prefer the same temperatures humans do. But humidity can be a little trickier to manage.

In their native habitats, humidity typically remains above 70%, sometimes going above 90% in the rainy season. Replicating this indoors if your climate is dry, can be a tough task. Unfortunately, if you don’t manage to raise humidity above at least 40%, your monstera leaves will begin to turn brown.

Lack of humidity typically causes the tips of the leaves to slowly brown, spreading inward as the problem worsens. These can eventually turn into large patches of leaves devoid of color, indicating a serious issue.

A humidity meter will quickly tell you whether this is the problem. You can raise humidity by placing the plant in a higher-humidity room, using a pebble tray, or misting a few times a day (although this can lead to fungal issues and more brown spots).

The most effective solution is to invest in a humidifier that will improve conditions for your monstera and all other tropical houseplants in your home.

Leaf Spot

Leaf spot is a common disease among not just houseplants, but all garden plants. Different types of leaf spot have different causes, from fungal to bacterial. But, as the name suggests, these issues all lead to spots forming on the leaves. These often start out yellow, fading to brown as parts of the leaves and stem die off.

Fungal leaf spot is more common in monsteras and causes light brown soggy spots to appear on the leaves and stems. These leaves need to be pruned off the plant to stop the problem from spreading uncontrollably.

There are some treatments you can try to fix the issue depending on the exact cause, but majorly infected plants are typically better discarded to stop spreading to other plants in your home.

Rust

Another fungal issue, rust is not common on indoor monsteras, but isn’t impossible either. Rust leads to patches of orangey-brown on the leaves and stems of the plant, typically clustered in the same area and spreading outward.

Quick treatment when rust is spotted is essential. This issue can quickly spread to other plants in your home or outdoors if not removed. Start by isolating the plant and cleaning any tools you have recently used on your monstera to protect your other plants.

Once isolated, treat the issue with neem oil or another fungicide designed for use against rust. Follow the instructions exactly to remove as much as possible. You may need to treat the plant several times before it is safe to bring back to its previous home.

Scale

Brown spots are typically a sign of another issue on your monstera. But, in the case of scale, those brown spots are the problem themselves. These sap-sucking insects attach themselves to stems and even leaves, forming hard and armored bumps.

You may miss them at first glance, but once they reproduce and spread, scale infestations are hard to miss.

Again, start by isolating the plant. Follow up with treatments of neem oil or insecticidal soap, rubbing on affected areas to remove all the visible bugs. You will likely need to apply the treatment a few times before the pests are completely gone.

Spider Mites

Spider mites are one of the most common indoor pests, identified by their webbing left between leaves and stems. They may be hard to spot on larger monsteras, but with a closer look, you should be able to see these tiny pests crawling around.

Spider mites suck the sap out of the leaves and stems to sustain themselves. They leave behind small yellow patches of damage that eventually turn brown, expanding as the bugs settle in.

Luckily, the same treatment of neem oil or insecticidal soap applies to these bugs too. You can start by rinsing off the plant to get rid of any visible bugs and webbing, treating afterward to tackle those that remain.

Thrips

Thrips are much more difficult to spot on monsteras, although they are also less common than the other two bugs. These microscopic pests are typically white or black, crawling over the surfaces of your monstera leaves.

They are usually identified first by the damage they do, including wilting and brown or black spots on the undersides of leaves.

Use the same treatments previously mentioned to tackle thrips, pruning away heavily damaged leaves to allow the plant to recover. Make sure you inspect nearby plants for signs of thrips in case they have already spread.