How To Treat Brown Spots on Calathea Leaves (An Easy Guide)

Brown spots on calathea leaves are a common issue caused by improper watering and direct sunlight. Low humidity can also contribute to this problem. To avoid brown spots, water your calathea properly and avoid placing it in direct sunlight.

Calathea plants are known for their vibrant and fascinating foliage that adds a touch of tropical paradise to any room.

Their lush green leaves and striking patterns make them a stunning addition to any indoor garden. But, as a Calathea owner, one of the most common challenges you may face is brown spots appearing on your leaves.

The good news is that treating and preventing these spots is easy once you know the cause.

This guide will help you figure out what is wrong with your plant, how to fix it, and how to stop it from happening again.

Causes of Brown Spots on Calathea Leaves

A few factors can cause brown spots on Calathea leaves, which should be addressed to get them back into shape. 

Let’s take a look at the most common causes. 

Overwatering

Overwatering is one of the leading causes of brown spots on Calathea leaves.

When a Calathea plant is overwatered, it creates an environment where fungal and bacterial infections can thrive. This can lead to root rot, which in turn causes discoloration and spotting on the leaves.

To identify overwatering, look for yellow or wilted foliage and slimy, dense roots that give off a foul smell.

If you suspect overwatering as the cause of your Calathea’s brown leaves, start by allowing the soil to dry out completely between waterings.

Underwatering

A telltale sign of underwatered Calathea plants is brown spots. The spots will be dark, dried, and brittle.

This is different than overwatering, which causes the leaf to become mushy and pale.

To prevent underwatering, consistently water your Calathea plant to keep the soil moist but not soggy.

Low Humidity

Low humidity is another cause of brown spots on Calathea leaves.

The ideal relative humidity level for a Calathea plant is between 50-60%. If you have lower than that, you may need to raise the humidity in your home.

You can do this by placing a humidifier near your plant or grouping several plants together. This will help create a more suitable microclimate for your Calathea.

Exposure to Direct Sunlight

Exposure to direct sunlight can cause brown leaves on Calathea plants.

Calatheas need bright, indirect light for optimal growth. Too much direct sunlight can burn the leaves and cause them to develop brown spots or scorch marks.

Look for bright yellow or orange spots on the leaves to know if your Calathea is getting too much direct sunlight.

It’s best to keep your Calathea in an area with bright light but away from direct sunlight. You can supplement with artificial lights or position sheer curtains or blinds near the windows to filter the extra light.

Pests

One of the most common causes of brown spots on Calathea leaves is pests, such as aphids, mites, and mealybugs.

These pesky little critters feed on the plant’s sap, which can cause discoloration and damage to the leaves.

To identify if your plant is affected by pests, you should look for small insects or clusters of waxy substances on the undersides of the leaves. You may also see yellow or brown lesions scattered across the foliage.

If you spot any of these signs, acting quickly and removing the pests is essential to save the plant.

Diseases

Certain diseases can also cause brown leaves on Calathea plants.

Some of the most common diseases that affect Calatheas include bacterial blight, root rot, and leaf spot.

If you suspect one of these diseases is the culprit, look for yellow or brown lesions on the leaves. You may also notice stunted growth or wilting of the plant.

If you find any of these symptoms, it’s crucial to isolate the infected parts and remove them immediately.

Nutrient Deficiencies

Nutrient deficiencies can also cause brown spots on Calathea leaves.

Calatheas need a good balance of nitrogen, potassium, and phosphorus to thrive. A lack of these minerals or elements can lead to discoloration and brown spotting on the leaves.

If you notice yellow leaves on your Calathea, test the soil and check for any nutrient deficiencies.

Adding a balanced fertilizer or supplementing with nutrients can help correct the deficiency and get your Calathea back on track.

Identifying the Cause of Brown Spots on Calathea Leaves

Brown spots on Calathea leaves can be caused by environmental, pest, and disease-related issues.

The first step to solving the mystery is to identify the cause.

To do this, look for any signs of overwatering, underwatering, exposure to direct sunlight, pests, diseases, or nutrient deficiencies.

Once you have identified the cause, you can take the necessary steps to get your Calathea back in good health.

Watering Habits

Calathea plants need consistent watering to stay healthy.

Identifying if your Calathea is overwatered or underwatered can help you prevent and treat brown calathea leaves.

If your plant’s soil feels soggy or mushy, it has likely been overwatered. If the soil feels dry and brittle, underwatering may be to blame.

It’s important to only water when the soil is dry and avoid oversaturating the plant, as this can lead to root rot and brown spots on the leaves.

Calathea plants need to be watered about once a week and misted regularly to maintain the proper humidity levels. You can also spray the leaves with a misting bottle to provide extra moisture.

Humidity Needs

Calathea plants prefer a humid environment.

When the humidity in your home drops too low, it can cause the foliage to dry out and become brittle. Further signs of a dry environment are crisp, brown leaf tips.

You can place your Calathea near other plants to increase humidity or use a humidifier to keep the air moist. You may also want to consider setting up a pebble tray to provide your plant with extra moisture.

Lighting Conditions

Calatheas need bright, indirect light for optimal growth. Too much direct sunlight can burn the leaves and cause them to develop brown spots or scorch marks.

Look for bright yellow or orange spots on the leaves to know if your Calathea is getting too much direct sunlight.

It’s best to place your Calathea in a spot that receives plenty of natural light but is not exposed to direct sunlight. If this isn’t an option, consider using sheer curtains or blinds near the windows to filter the extra light.

Pest Infestation

Pests, such as aphids, mites, and mealybugs, can cause brown spots on Calathea leaves.

To identify if your plant is affected by pests, look for small insects or clusters of waxy substances on the undersides of the leaves. You may also see yellow or brown lesions scattered across the foliage.

If you spot any of these signs, acting quickly and removing the pests is important to save the plant. Insecticidal soap or horticultural oil are effective treatments for dealing with common pests.

Fungal or Viral Infections

Fungal or viral infections can also lead to brown spots on the leaves.

These issues are more challenging to identify, as they require knowledge of fungal and viral diseases that affect Calathea plants.

Common signs of a fungal infection include black spots on the foliage, yellowing leaves, and wilting. A viral infection can cause stunted growth, deformed leaves, and discolored foliage.

Testing for Nutrient Deficiencies

If your Calathea is not receiving enough nutrients, it can cause brown spots on the leaves.

Testing the soil for nutrient deficiencies is an excellent way to identify if this might be the problem. Common nutrient deficiencies that can cause brown leaves include nitrogen and potassium.

To identify these deficiencies, you can purchase soil test kits at most garden stores. Once identified, apply an all-purpose fertilizer that contains the necessary nutrients for your Calathea.

Treating Brown Spots on Calathea Plants

Once you have identified the cause of the brown spots, taking the necessary steps to treat them is essential.

Adjust Watering Frequency

The most common causes of brown spots on Calathea leaves are caused by either overwatering or underwatering the plant.

To adjust your watering schedule:

1. Check the soil of your Calathea’s pot before adding more water.
2. Stick your finger in the soil up to around two knuckles deep; if it feels wet, do not add any additional water.
3. If the soil feels dry, add water and ensure the excess water drains out of the pot.

Adjust Sunlight Exposure

Another common cause of brown spots on Calathea leaves is too much direct sunlight exposure.

Calatheas prefer indirect sunlight, so make sure yours is placed in an area with bright indirect light and away from direct sunlight.

Observing how the leaves grow is the best way to check if your Calathea is getting enough light. If they appear to be leaning towards the light source, that’s an indication that it might not be receiving enough light and should be moved closer to a brighter spot.

East- or west-facing windows are usually the best spots for Calathea plants. These windows provide bright, indirect light that is perfect for Calatheas.

Treat Pest Infestations

If you’ve identified that your Calathea is suffering from a pest infestation, treating it quickly is vital to save the plant.

Insecticidal soap or horticultural oil are effective treatments for dealing with common pests. Make sure to thoroughly spray all parts of the plant, especially the undersides of the leaves, with the solution.

Treat Fungal or Viral Infections

If your Calathea is infected with a fungal or viral infection, treating the plant as soon as possible is essential.

Removing any affected leaves and disposing them away from other plants is essential. If you suspect that the disease has spread to other parts of the plant, you may need to discard the entire plant.

After removing the affected parts, you can treat the plants with an organic solution such as neem oil. Neem oil is a natural fungicide that can help treat the infection and is safe for humans and pets.

Apply a Fertilizer

If you’ve identified that your Calathea has a nutrient deficiency, applying a fertilizer that contains the necessary nutrients can help treat the brown spots.

To pick the right fertilizer for your Calathea plant, check the soil for nutrient deficiencies. Common ones that can cause brown leaves are nitrogen and potassium.

Go to a garden store and buy a test kit to help you figure it out.

When you know what is missing from the soil, get an all-purpose fertilizer with those nutrients.

Then use the right amount of fertilizer – not too much or too little – so you don’t get brown spots again.

Applying the fertilizer once or twice a month is usually enough; however, be careful not to overfertilize, as this can also cause brown spots on the leaves.

Preventing Future Brown Spots on Calathea Plants

When it comes to plants, prevention is key. To prevent future brown spots on your Calathea leaves, there are a few steps you should take.

Properly Care For Your Calathea

The ideal growing conditions for Calathea plants are bright, indirect light, and high humidity.

Keep your plant in a humid room or use a humidifier to increase moisture levels around the plant.

Ensure to water regularly but avoid overwatering, as this can lead to fungal diseases and root rot.

Regularly Inspect Your Plant

Routine check-ups are a great way to ensure your Calathea is healthy and free of pests, diseases, or nutrient deficiencies. Take the time to inspect your plant for any signs of brown spots at least once a month.

Quarantine New Plants

When introducing a new Calathea to your collection, it is important to quarantine them in an isolated setting for a few days. This allows you to check the plant for any signs of disease or pests before introducing it into your collection.

Proper Sanitation Practices

Properly sanitizing your tools and space when handling plants is essential. This helps reduce the risk of spreading pests or diseases from one plant to another, which can cause brown spots on leaves. Be sure to wash and disinfect all your tools before use properly.

Avoid Overcrowding

The last step to preventing future brown spots is avoiding overcrowding plants.

Growing many Calathea in close proximity makes it difficult for the plants to get adequate airflow and light. This can cause fungal diseases and nutrient deficiencies, leading to brown leaves.

Final Thoughts

Calathea care is all about balance. Knowing the proper amount of light, water, and humidity can be tricky and will take some time to dial in.

But when you get it just right, Calatheas are stunning plants that brighten up any space.

With the help of these tips for preventing brown spots on your Calathea leaves, you’ll be able to keep your plant looking healthy and beautiful.

So don’t get discouraged if you’re running into problems – take it one step at a time and enjoy the journey of caring for your Calathea!