Peace Lily Leaves Turning Black (And How to Fix it)

The Peace Lily (Spatiphyllum) is one of the most popular houseplants because of its beautiful leaves and flowers.

Unfortunately, you may wake up one day to the unpleasant surprise of seeing black spots on peace lily leaves. So, what gives?

And more importantly, what should you do?

In this article, I’ll discuss the causes of black spots on peace lily foliage and how you can fix each of these problems.

Why is my peace lily turning black? Black spots on a peace lily’s leaves usually means it has a fungal infection. More specifically, it is likely some kind of leaf spot disease.

But that’s not the only reason. Other causes include watering issues, fertilizer problems, incorrect lighting or using an improper potting mix.

Causes Why Peace Lily Leaves Turn Black

Below, I’ll list out the most common causes of black spots on peace lily leaves. This way, you’ll be aware of the different things that can make your beloved peace lily turn black.

Note that there are quite a few reasons.

Therefore, you’ll need to narrow them down to find the actual cause.

This is important since time is of the essence. As such, your plant may not have time for do-overs if you just guess and try the wrong solution.

 

Watering Problems

Black spots on peace lily can happen due to watering issues.

Unfortunately, both overwatering and underwatering will cause your peace lily to turn black. So, it is very important to avoid the extremes.

Instead, watering moderately as the plant is not a fan of going very dry or sitting in excess moisture.

To explain each, it important to go back to the peace lily’s natural habitat which is the tropical rainforest.

As such, the plant gets a lot of rain on a daily basis.

However, the soil does not stay very wet for long. Instead, it dries a bit and becomes moist.

This is why peace lilies don’t like being underwatered. Of course, it hates getting dehydrated.

Why?

When the root ball gets completely dry or stays dry for extended periods of time, it will have a hard time transporting nutrients to the different parts of the plant, including the leaves.

In addition to nutrients, these parts also need moisture.

As such, the plant’s growth will slow down or completely stop.

It will also shrivel and shrink along with the black spots developing on its leaves.

If this condition persists, the peace lily will deteriorate and possibly die after a while.

Meanwhile, overwatering can be even more fatal.

In this scenario, the plant gets too much water. Often, this is due to being watered too frequently.

So, even when the soil is still moist or wet, it receives more water.

After a while, the roots will drown in all that excess moisture. And because they cannot breathe, they will suffocate.

If the excess moisture does not dry or drain in time, the roots will die of suffocation.

Dead roots will rot.

More importantly, dead roots don’t function anymore.

Thus, the longer the peace lily is overwatered, the more roots will rot until the remaining healthy roots cannot support the plant anymore.

This is why overwatering is very dangerous.

It does not take a long time to kill the plant.

 

Solution

Find a schedule where your peace lily gets enough water.

The goal is to keep the soil moist. Although, it is safer to day on the dry side.

However, avoid letting soil go bone dry.

This is the only thing to watch out for on the dry side.

So, the best way to do this is regularly check the soil. Stick your finger into the soil down 2 inches from the surface.

As long as the soil at that depth is moist or wet, never water.

Only water once the soil 2 inches from the top is completely dry. You can also water after that as long as you don’t let the entire root ball go completely dry.

 

Water Quality

The quality of your home’s tap water can also cause black spots on peace lily leaves. And they can cause the leaves to turn brown, yellow or cause other colors as well.

The resulting color will depend a lot on what nutrients the plant ends up deficient in.

The reason this happens is that some homes have highly mineralized water. Others also have hard water.

The problem with these is that excess minerals and salts in the tap will affect how much water and the amount of different nutrients the roots take absorb from the soil.

In general, salt draws moisture. As such, the more salts there are in the water, the more salt residue there will be left in the soil.

This will prevent the roots from efficiently absorb moisture as well as certain nutrients.

And the more you water the plant with that tap water, the worse it leaf discoloration will get.

 

Solution

To avoid black spots on peace lily leaves and other discolorations, it is a good idea to monitor how the plant responds to tap water.

I’ve notice that not all municipalities add excess amounts of minerals in the tap.

But some do.

So, you may or may experience this problem depending on the city you live it.

However, there’s no way to be sure but to monitor your peace lily to see if its leaves turn black, brown, or another color besides green.

If the plant stays healthy and its leaves have a lovely green color after the first month or so, then it is safe to say that you won’t have to deal with highly mineralized tap water.

But if the leaves change color, then it is important to address the situation.

The discolored leaves won’t return to green even if you fix the issue. So, you’ll eventually need to prune them or trim off the affected areas.

But they will keep turning brown, black and other colors unless you fix the source of the problem.

Here, you have a few options, you can:

  • Collect rainwater and use that
  • Filter the tap water
  • Use distilled water
  • Let the tap water sit overnight or longer to allow the minerals to evaporate first

 

Fungal Disease

Black spots on peace lily leaves is commonly caused by fungal infections.

Here, you’ll see a variety of different leaf spot disease that can cause black spots on peace lily leaves. As such, it is important to avoid fungi infections as much as possible.

In general fungi thrive in wet, damp or moist conditions.

So, overwatering the potting soil, wetting the leaves and stems excessively are the biggest no-no’s.

You want to avoid doing this.

I’ve already talked about overwatering the soil above.

The other causes usually occur when you water the plant overhead. The best way to do this is to pour directly on the soil.

But many people will water above the entire plant.

With the latter, everything ends up wet including the leaves and stems. Additionally, the soil does not get a lot of water because many end up splattering on the leaves.

If the leaves stay wet for prolonged periods of time, it increases the chance of fungus development. This is how leaf spot infections occur.

Another sneaky cause is misting.

Many people like misting their houseplants to help keep humidity around the plant high.

While this is a good idea especially if you have low humidity in your home, avoid over spraying the leaves.

Leaving them wet or allowing water spots to build up on foliage also increases the risk of fungal growth.

 

Solution

The best way is to fix this problem is to modify the way you water.

This means not wetting the leaves when watering your peace lily. Instead, water directly on the soil itself.

Also, when misting, don’t over mist the leaves such that they end up wet.

In case you accidentally wet the leaves, you can use paper towels to pat them dry. This will let them dry up much faster.

It is also a good idea to keep the plant in bright, indirect light and a spot with good ventilation. These conditions will help wet spots dry faster.

However, if your peace lily has black spots due to fungal infections, then it is important to immediately treat the plant.

I like to go with more natural methods. So, I use baking soda.

Baking soda has anti-fungal properties. Just as importantly, it is not toxic to plants.

To use it, mix:

  • 1 teaspoon of baking soda
  • 1 liter of water

You can scale this mixture up or down. Then place in a spray bottle and shake to mix thoroughly.

Spray this solution on the black spots on the peace lily leaves.

Keep applying until the fungi disappears.

But if you prefer to just buy something, you can use a fungicide to get rid of the black spots on the peace lily leaves.

 

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Root Rot

Black spots on peace lily also happen with root rot.

This is a tricky one because the problem occurs under the soil. So, until the symptoms reach the upper part of the plant, the problem stays hidden.

Unfortunately, because of how possibly fatal root rot is, it becomes essential to observe that natural color of your peace lily’s leaves.

This way, if there are any subtle changes that point to possible root rot, then take immediate action.

With root rot, your peace lily will turn black or brown.

But it will begin in the roots. So, they’re initially hidden until you discover the problem.

Roots rot due to overwatering. And they will turn from their healthy white color and become brown or black. They will also stink and become mushy to the touch.

After a while, the symptoms of root rot will work their way up.

And you’ll see your peace lily start looking weak then wilt.

Its leaves will also experience discoloration, changing from their green color to yellow.

As root rot progresses, you’ll also see brown then black leaves on your peace lily.

 

Solution

Root rot can occur due to suffocation because of the excess water in the soil.

In this case, the roots eventually die and then rot.

However, because of the wet environment of the soil, fungal infections can also develop. Thus, fungal root rot is also another possibility.

As such, it is important to avoid excess moisture in the soil.

This is why root rot is often caused by one of 3 things.

  1. Overwatering or watering the plant too often.
  2. Waterlogged soil due to the soil retaining too much moisture and lack of soil drainage.
  3. Using a pot with insufficient drainage.

By making sure you cover all these 3 potential causes of root rot, you’ll be able to avoid the problem.

However, if your peace lily already has root rot. And the root rot is what’s causing the black leaves, then you should focus on saving the plant.

The first thing to do is stop watering.

Next, check the root system. If only part of the root system has rotted, there’s still a chance to save the plant.

But it almost all the roots or all the roots have rotted, then it is unlikely the peace lily can be save.

Therefore, with the latter, your best bet is to propagate your peace lily.

This will be your backup plan. And it will let you grow a new peace lily plant that will grow into a clone of the parent.

Doing this gives you safety net in case the mother plant succumbs to root rot.

But if only a portion of the root system has rotted, prune the rotten roots. Then disinfect the plant, the pot and throw away the soil.

After that, repot the plant in fresh, dry, well-draining potting mix.

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