The peace lily is an excellent houseplant with ornamental qualities. It is painful to see peace lily leaves turning black.

The blackening of leaves is a common problem and one can easily heal the plant by identifying the cause.

Today I’ll talk about all the possible causes of this problem with solutions and prevention tips.

Black peace lily leaves are often a result of fungal disease and pest infestations. Overuse of fertilizers, wrong potting soil, low humidity, and lack of sufficient light are other common causes of the blackening of a peace lily.

Over Watering

If the potting soil is saturated with water and peace lily leaves are turning black. This means you are giving too much water to your plants.

Peace lily roots cannot handle the huge amount of water. Roots go into a shocking state and try to absorb a maximum of water to save them from root rot.

This extra water goes into all parts of the plant. When peace lily leaves are pushed to store extra water. Their cells get damaged and you see tiny black dots on leaves.

If you did not catch the problem at this stage. Then these small black spots increase their circumference and the entire leaf turns black.

Or

If your peace lily roots are already damaged with root rot due to waterlogged soil. Then within 7 to 10 days, your entire plant will turn black without any warning sign.

To identify the root rot in peace lily you need to smell the potting soil. If it smells like rotten eggs or decaying, this indicates the presence of root fungus underneath the soil. 

In this case repotting is the only solution to save peace lily.

Solution

To save your peace lily from turning black. You need to repot the plant immediately in the fresh soil.

Gently remove the soil from the pot with your hands. Don’t use the tools to prevent damage to the stems.

Then tilt your plant pot and gently unpot your peace lily.

Remove the soil from the roots and identify the damaged parts. Gently cut the damaged roots with a sharp knife.

Discard the potting soil and wash the pot with soap and warm water. Add fresh soil to the pot and plant peace lily back in it.

Move the plant in indirect bright light to speed up the healing process.

And

To prevent overwatering issues always check the soil conditions before watering peace lilies. If the soil has a good amount of moisture no need to water it.

And, if the top 2 inches of the soil are dry this means your plant is thirsty, and give some water for hydration.

Low Food Production in Peace lilies

Tropical plants like peace lily need less light than other houseplants. But this does not mean they don’t need light at all.

When people place their lilies in very low light. The chlorophyll pigment presence on the leaves becomes unable to absorb a good amount of light energy.

Root also becomes weak and did not absorb a good amount of water and nutrients.

The lack of water, nutrients, light, and a weak function of roots results in insufficient production of plant glucose.

Glucose is the energy source of plants. They use it to stay healthy, green, and vibrant.

In the absence of an adequate amount of food, peace lily leaves turn black.

Solution

To encourage your plant to make the proper amount of food for itself. You should place your peace lily in the indirect bright light.

Do not expose your plant to direct sun rays. Because the sunlight is too intense for the peace lily leaves. They cannot tolerate the direct light wavelength of the sun.

The best place for peace lily plants is near the sunny window. Just place it a few feet away from the window sill.

Or

You can use the sheer curtain to filter the sunlight that is entering from the window.

Underwatering

Peace lily constantly needs moist soil. To keep the soil moisture level at optimum you need to give proper water to the plant.

But when you forget to water your peace lily this turns its leaves black due to dehydration.

Underwatering causes two problems one is dehydration and the second it affects the production of food as explained in the above point.

In low water situations, roots don’t have enough water to transport to other parts of the plant. Moreover, roots absorb nutrients with the help of water.

As a result, your plant becomes dehydrated and nutrient deficient.

Both these conditions turn leaves yellow and then black if you leave your peace lily on their own.

The early warning sign of dehydrated peace lily is shrunken and wrinkled leaves.

Solution

To heal dehydrated peace lily plants, immediately give them a good amount of water. It is best to use a deep watering technique.

In which we take a tub of water and put the plant in it. Then the plant soaks a good amount of water from the bottom drainage hole.

This way we are directly supplying the water to dehydrated roots. The roots quickly start working properly and within a few days, peace lilies again become healthy and bright.

To prevent underwatering conditions remember that in the summer season peace lily needs frequent watering sessions.

Or

Self-watering planters to get rid of water headaches. You just need to fill the reservoir once in 30 days. Self-planter will automatically send water to your roots when they need it.

They are not expensive anymore you can check the price on amazon.

Poor Quality Water

Water containing chlorine, fluoride, and other impurities is poor quality water for plants.

These salts settle at the base of the plant pot and disturb the roots.

The presence of chlorine in huge amounts disturbs the pH of the plant roots. It makes the pH of the soil and plant acidic.

Roots cannot absorb nutrients in an acidic environment.

When these ingredients go into the leaves, they cause inflammation and damage the leaf cell walls.

As a result, the leaf cells start decaying and this makes your peace lily black.

Solution

If your peace lily leaves are already black and you are sure that poor quality water is the cause.

In this situation unpot your plant and wash the roots with filtered water.

Place your plant on newspaper for some time and run filtered water through the potting soil. You will see the white slats coming through the drainage hole.

Do not stop until you see the clear water coming from the bottom holes of the pot.

Then plant your peace lily back in the pot and let it drain extra water. It will take 30 minutes to drain extra cups of water.

Then empty the saucer and place your plant in its permanent place.

Using Hot or Cold Water

Using too hot or too cold water invites many problems and black peace lily leaves are one of them.

In the botanical world, we call it a water shock.

Actually, the hot water increases the overall temperature of the plant tissues and increases respiration.

We all know hot water is not required for photosynthesis. It will only harm the internal leaf tissues and turn them black.

Whereas cold water decreases the normal temperature of peace lilies. As a result, the leaf tissues shrink themselves to keep them warm.

This unnatural shrinkage of leaves results in large black spots on peace lily leaves.

Solution

To correct the issue immediately shift to the normal room temperature water.

20 degrees C to 25 degrees C water temperature is perfect for watering plants. But we cannot measure the water temperature every time we water plants.

Therefore, the golden rule says water that you can easily drink is perfect water at the perfect temperature for your plants.

Now don’t start drinking plant water to check the temperature, just put your finger in it to check.

Leaf Fungal Infection

Peace lily turning black due to the leaf fungal infection is a common problem. A moist environment and unhygienic surroundings invite fungal diseases.

Following are the signs of fungal infection:

  • Grey or black circles on leaves with a yellow center
  • Leaf spots with purple or reddish borders
  • Leaf spots are present in dark concentric ring forms

Solution

The first treatment that I recommend is a natural way without damaging the plant. Baking soda is anti-fungal and is not toxic to plants and humans.

To prepare the anti-fungal spray dissolve 1 tablespoon of baking soda in 1 liter of filtered water.

Spray this solution on peace lily leaves. You will see significant improvements in 3 to 4 days.

 But,

If all the leaves are infected with fungal spot disease. Then the only effective option left is using professional fungicides.

Go to your local garden and buy a fungicide or you can use what I found is effective in treating fungal diseases. Check it on Amazon.

These sprays are toxic to humans and wear gloves and a mask before using them. Read the instruction carefully and separate your peace lily from other healthy plants.

Move it outdoors to use the anti-fungal sprays.

Peace-Lily-fungal -Leaves

Direct Sunlight

Peace lily can handle indirect bright light but direct sunlight is destructive. The sharp sun rays that fall on the leaves increase the temperature of the leaves.

The continuous falling sunlight burns the leaves and you see small dark spots on the peace lily leaves.

This is the damage caused by highly intense light and is irreversible.

Within 5 to 7 days the sunlight completely damages the cell walls and damages the leaf nucleus.

Once the nucleus gets damaged the entire peace lily leaf turns black.

Direct sunlight also damages the nucleus of stems which is a cause of peace lily death. We cannot revive the plant with a damaged central nervous system.

Solution

Before bringing peace lily home, you should learn about Peace lily care requirements. By knowing about its needs, you can easily prevent accidental exposure to sunlight.

To help your plant move it to a shady place and give it some water and nutrients.

Do not frequently change its location or your peace lily goes into stress. Then it will be difficult for you to revive it back.

Excessive Use of Fertilizers

By overusing the fertilizers, you are supplying more amount of nitrogen to your plant. This extra amount of N increases the acidity of the growing medium.

It creates a chemical imbalance and this affects nutrient uptake.

Due to the acidic soil, the availability of copper, magnesium, and potassium decreases by a significant amount.

Lack of all these essential nutrients leads to a leaf condition called necrosis with half black portion.

Solution

It is easy to get rid of the extra amount of nitrogen in the soil. Leach the potting soil with clean filtered water.

Give a sufficient amount of water so that pollutants can come out with water from drain holes.

At last use alkaline water to balance the pH of the potting soil and test the soil pH.

Lack of Phosphorous

If your fertilizer is not containing a sufficient amount of phosphorous. You will 100% face the blackening of peace lily leaves.

Lack of phosphorous is not very common but it happens when you use poor quality potting soil or cheap fertilizer.

At first, the leaves start turning black from their tips moving towards the leaf node.

Other symptoms:

  • Black and purple spots on leaves
  • Leaves are turning back from their tips

Solution

Change the current soil and use high-quality soil that contains some organic material and balanced pH.

Use phosphate fertilizer if the soil is good but the fertilizer used was bad quality and does not contain a sufficient amount of phosphorous.

Start using quality liquid fertilizers

Low Humidity

Humidity is essential for growing a healthy peace lily plant. If your plant is in a low humid location for example, near the heat generators, oven, etc.

Then blackening of peace lily leaves should not be a surprise.

Lack of humidity in the air can kill your plant in a few days. Back leaves are just the starting of a hard time for your plant.

Solution

To fix it just increase the room humidity. 50% to 70%  humidity in the air is the ideal range for peace lily plants. You can use the pebble tray method

Or

You can choose a professional solution for a plant humidifier.

The solution depends upon your budget. The Pebble tray method only increases 7 to 10 % humidity.

Temperature Shock

The normal temperature of tropical jungles stays above 75 degrees F. This indicates that peace lily needs warm weather to grow.

Keep the temperature of the growing room above 70 degrees F at all times.

In cold temperatures the metabolism of plants gets imbalanced. As a result, its leaves start wilting and your plant becomes weak.

Later the wilted leaves start turning black.

Solution

Choose a warm room to grow peace lily plants. Install the room temperature meter to monitor the grow room temperature.

Do not use heating fans to give it warm air. This will increase the problems.

You can cover the plant pot with a plastic bag so that the cold air cannot touch the potting soil. I use dry straws to keep the plants warm that in growing in my garage.

Pest Attacks

If you think above listed causes are not responsible for turning leaves black of your peace lily. Then you must check for pest attacks.

Closely inspect your plant to see the tiny insects on the surface of the leaves and undersides too.

Aphids and mealybugs are common culprits of black peace lily leaves.

They suck the sap of your plant and make it nutrient deficient and also damage the leaf surface.

Solution

Use insecticidal soap to rinse your plant. This method will kill all the bugs and did not harm the plant.

Keep it separate until you see healthy growth signs.

After the treatment uses neem oil spry to prevent pest infestations.

Do not use pesticidal sprays because peace lily cannot handle the chemicals used in these strong sprays.

How to Prevent Peace Lily Leaves from Turning Black?

To prevent the blackening of peace lily leaves you need to give them proper care. There are some factors that are important and you have to keep them in mind.

The Right Soil

The right type of soil can prevent many problems like overwatering, underwatering, and blackening of peace lily leaves due to imbalanced pH.

Choose soil that has some organic ingredients.

Organic ingredients like organic compost give a sufficient amount of nutrients to young peace lily to grow healthy.

Watering Application

Limit the use of water especially in the winter season to avoid root rot. In summer always check the soil moisture before watering the plant.

I use a soil moisture meter to make things easy for me.

Also, use filtered water, avoid using tap water it may contain unwanted chemicals like chlorine and fluoride.

Use Organic Nutrients

The peace lily is a small size plant with beautiful leaves. To keep your plant happy and thriving you should only use organic fertilizers.

These are mild on plant roots and make a continuous chain of nutrient supply.

This speed up the growth of a plant and reduces the chances of overfertilization burn and blackening of leaves.