Most indoor plants are loved for their ornamental leaves. But the last thing you would want is black leaves in the indoor plants. Many houseplants are prone to this issue.
Indoor plant leaves turn black due to watering issues, poor drainage, pests, fungal and bacterial infections, cold drafts, humid weather, or excessive fertilization. Improve watering, ensure drainage, deal with infestations, avoid cold drafts, improve air circulation, and fertilize sensibly.
Are you struggling with black leaves in your indoor plant? Please read this article till the end as we explore the most common reasons causing black leaves, easy solutions, and ways to prevent this issue from further occurring.
Table Of Contents
I have done my best to address all of your concerns in the article below. However, if you still have any questions or are confused about the article, you can receive personalized one-on-one assistance from me by leaving a comment below. I will respond to your comment within a few hours.
Please note: Simplify Plants is reader-supported. Some links in the post are affiliate links and I get a commission from purchases made through links in the post.
7 common causes of black leaves in indoor plants
Nothing is more disheartening than detecting black leaves in our precious indoor plants.
It is the last thing plant lovers would want.
The problem is common, and some houseplants are prone to this issue.
Your indoor plant will never grow black leaves suddenly unless it is of a fungal or bacterial disease.
It begins with yellowing, which gradually turns brown or black.
If the problem is not addressed in time, your plant may die.
So it is crucial to diagnose the reasons and solve them soon.
As a beginner, I have faced several issues with many of my houseplants.
Unfortunately, black leaves were one of them.
Even though I managed to revive my plant, I thought of knowing all the possible reasons so that I could stay prepared for the future.
Here, I have shared the most common reasons for black leaves in the indoor plant and how to resolve them.
Let’s understand them in detail:
1. Leaves turning black due to overwatering and root rot
One of the main reasons behind black leaves on indoor plants is overwatering.
The problem starts at the roots and slowly spreads upward.
Plants vary in their watering requirements.
Some prefer consistently moist soil, while others thrive in drier conditions.
The air exchange gets disturbed, and roots suffocate when they remain wet constantly for too long.
Once the roots are affected, the plant cannot absorb moisture and nutrients effectively.
These further cause chlorosis, where the leaves turn yellow, brown, or black.
Overwatering for prolonged periods initiates Root rot, where lack of oxygen and toxin accumulation in the root area affect the plant’s metabolic process, causing wilting and black leaves.
As the rotting progresses, it will reduce the plant’s defense system and make it prone to diseases.
To confirm root rot, take your plant out, and you will find brown, mushy roots and a foul smell.
Signs of overwatering and root rot are:
- Leaves turning black and dying
- Plant looks weak
- Soil near the roots is wet and smelling
- Leaves turning yellow and then black
Rescuing an overwatered plant
- Eliminate the cause of overwatering and root rot by reducing watering.
- Water the plant only when the top few inches have dried.
- If the root rot has progressed, transplant it into a new pot with new soil. Cut off the damaged roots, spray some fungicide, and repot your plant in a new pot with new soil.
2. Leaves turning black due to poor drainage
Poor drainage also causes overwatering and root rot despite the correct watering techniques.
With poor drainage, the water stays stagnant around the plant base.
Most plants will need well-drained soil that drains excess water because no plant loves stagnant water.
Compact and clayey soils or pots without drainage holes are responsible for it.
Improving drainage to reduce black leaves
If your pot doesn’t have drainage holes, either make one or repot to a new one with drainage holes.
3. Black leaves due to fungal infections
The next common reason for the black leaves is fungal infections, for example, Leaf Spots or powdery mildew.
In a leaf spot disease, the leaves will initially have black spots, enlarging over time and turning the entire leaf black.
In powdery mildew, the leaves will have scattered powder marks.
The leaves will turn yellow, brown, and black as time passes.
Fungal pathogens love wet and humid conditions and spread quickly through water splashes.
The spores stay dormant until they get activated by water.
Identifying and treating plant fungal diseases
To save an infected plant, you need to improve your watering practices.
Here’s what you can do:
- Let the soil dry out and keep the plant at a location that receives bright, indirect sunlight. It can kill the pathogens to some extent.
- Remove the infected leaves to reduce any further contamination.
- Water at the base instead of the leaves. Wet leaves can activate the spores.
- Water early in the morning. Your leaves and the plant will have enough time throughout the day to dry out.
- Allow good air circulation to prevent the spores from spreading.
- Do not mist your leaves. If you need to increase humidity, use a humidifier and try the pebble tray method.
- Along with these, Organic commercial fungicides are a good choice. Spray some on the infected parts to kill the pathogens. However, these products can be expensive if the infection is too much.
- Try neem oil. It is cost-effective, eco-friendly, and a natural product that helps treat pests and diseases. However, it won’t kill the fungi but smother the spores to avoid spreading. Coat the foliage with the oil and let it stay. Do it every 15 days. Make sure to use it without letting the plant be exposed to the sunlight; that will burn the leaves.
- Use some homemade fungicides. Mix one tablespoon of baking soda with one gallon of water. Add one teaspoon of horticultural oil or insecticidal soap and let it stick to the plant. It will alter the leaf’s pH level, make an unlivable environment for the fungi, and kill them.
4. Insect infestation causes black leaves in the plant
Pest infestation is one of the most irritating issues.
The typical offenders are aphids, spider mites, whiteflies, scales, and mealybugs.
The sap-sucking insects like aphids, whiteflies, spider mites, and scales pierce the plant tissues to suck the sap from the leaves.
During the process, they leave behind a sticky substance called honeydew.
This honeydew attracts sooty mold fungus, turning leaves black.
Check if the leaves feel sticky whenever you notice black leaves, and you will understand the problem.
Eliminate these pests soon; otherwise, they can weaken and kill your plant.
To eradicate the pests:
- Shower your plant to dislodge the pests from their place. Focus more on the underside of the leaves.
- Apply some horticultural oil, like neem oil, on the infected parts.
- Dab a cotton swab into rubbing alcohol and remove the pests if you see them.
- Use pesticides if the infection is too much.
Address the sooty mold by removing the sticky secretions using rubbing alcohol.
Spray a broad-spectrum fungicide to stop the blackening.
If any leaf has turned entirely black and revival seems impossible, cut off the affected leaves.
5. Leaves turning black due to bacterial and viral infections
Black leaves on indoor plants can also signify bacterial and viral infections.
The main reasons are overhead watering, lack of sunlight, poor ventilation, and leaves staying wet for too long.
If you find any black spots enlarging and spreading over the leaves, remove them immediately.
Managing bacterial infections in the plant
The best way to manage bacterial and viral infections is prevention:
- Provide extra care to increase the plant’s ability to fight the infection.
- Sanitize your gardening tools before and after use with rubbing alcohol.
- Maintain proper ventilation between each plant. If you are grouping them, keep the leaves from touching each other.
6. Leaves turning black due to frost exposure
Most indoor plants are tropical plants.
They love warm temperatures and not freezing conditions.
Freezing temperatures can harm the plant’s tissues and vascular system, including the xylem and phloem.
The xylem moves water and nutrients from roots to leaves, while the phloem transports sugars and compounds within the plant.
Frost disrupts this process, affecting leaf health by hindering nutrient transfers.
The ruptured cells and disrupted vascular system can kill the leaf tissues.
The leaves will turn black or dark brown when the cells die due to necrosis.
Reducing cold drafts to reduce blackening
If you find black leaves and the other issues are not the culprit, check for the temperature of your room.
Maintain a temperature that is ideal for your specific houseplant.
Most indoor plants are from tropical areas and enjoy temperatures between 60-75°F.
You can use heat mats for your potted plants.
Avoid keeping your plant close to open doors, windows, and HVAC rooms.
If your treatment is correct, you will soon notice new growth in the plant.
7. Leaves turning black due to low humidity
Plants transpire naturally, where they lose moisture through their leaves.
Transpiration reduces when the surrounding air gets dry due to low humidity levels.
It can increase moisture loss and evaporation faster than its absorption from the roots, causing water scarcity.
The leaves can start wilting and turn brown or black.
Increasing humidity levels
Since most indoor plants are tropical, they love high humidity above 50%.
You can mist the leaves regularly, ensuring that the leaves do not stay wet for too long.
Other ways to increase humidity are:
- Adding a humidifier
- Consider the pebble tray method
- Keeping the plant close to the aquarium
- Grouping the plants for natural humidity rise
- Keep a hygrometer in your room to check the humidity and approach methods to keep the humidity in check.
Other reasons causing black leaves in the indoor plant
Except for the above common reasons, a few other reasons can lead to black leaves.
These factors are less likely to cause black leaves, but they can’t be ruled out. Let’s have a quick look:
Leaves turning black due to nutrient deficiency
A lack of nutrients can disrupt essential metabolic processes, resulting in symptoms such as black leaves.
For example, iron helps in chlorophyll, and iron deficiency causes chlorosis or yellowing, progressing to black over time, especially along the leaf veins.
Zinc helps in enzymatic activities; zinc deficiency leads to interveinal chlorosis.
Over time, the affected leaves turn black.
Fix nutrient levels by using balanced fertilizer with necessary nutrients for your plant.
A lack of phosphorus can cause black leaves.
Out of the 3 primary nutrients – nitrogen, phosphorus, and potassium – phosphorus plays a significant role in the plant’s overall growth and development.
Phosphorus deficiency can cause a purplish-black color at the top.
Over time, the color will progress to black.
You will also notice stunted growth.
One common reason behind phosphorus deficiency is highly acidic soil.
The plant struggles to absorb it from the soil.
Adding phosphorus separately isn’t going to solve the issue.
First, check and adjust the soil’s pH level by adding garden lime to neutralize the acidic soil.
Next, apply some phosphate fertilizer.
Underwatering can cause black leaves.
Sometimes, a dehydrated plant can also have black leaves.
Plant dehydration for prolonged periods makes the leaves extremely dry and crispy.
Initially, the leaves turn brown and, over time, progress to a black color.
To reverse the problem, check the soil and see if it’s dry.
Water the plant slowly and steadily, saturating the soil well until the excess drains.
After some days of regular watering, you will see new growth.
Leaves turning black due to direct sunlight exposure
Most indoor plants enjoy bright, indirect sunlight.
Intense sunlight scorches the leaves, turning them brown and then black.
Remove the affected leaves and adjust the light conditions by relocating your plant to an area with bright, indirect sunlight.
A west or east-facing window might work.
Put on sheer curtains or Venetian blinds to filter the direct sunlight.
It can reduce the sun’s intensity and hot temperatures.
Increase watering the plant.
It will keep your plant cool and prevent scorching.
Leaves turning black due to overfertilization
Gardeners use fertile soil to provide enough nutrients to their plants.
But your plant may not need so much fertilizer.
For example, excessive nitrogen causes rapid leaf growth.
It fails to mature and become soft.
Over time, these leaves get prone to rotting and mildew, which turns them brown or black.
Symptoms of over-fertilization are:
- A small part of the leaf is turning black and dying
- The plant has a white crust on the soil surface
- Leaves turning black and falling off
- To fix an over-fertilized plant causing black leaves:
- Use plenty of water to flush the plant and remove the excess salt buildup.
- Remove the damaged leaves.
- Consider flushing once a month.
- Give a break to fertilization for a few weeks. Next, fertilize only 2-3 times a season.
- If the potting soil is over-fertilized, repot your plant with new soil.
Restoring and preventing black leaves
By now, you know all the reasons that can lead to black leaves and solutions to fix the conditions.
But how do we restore the black leaves?
Unfortunately, the leaves that have turned half-black or entirely black cannot be revived.
They will not turn green. So, you have to prune them off.
As for the leaves that have just started turning black, they might be saved.
Provide the proper treatment for the specific and wait to observe the plant curing.
If you have diagnosed the correct cause and provided the proper treatment, you will soon notice new leaf growth and good development speed like before.
Once you have treated your plant and revived it from blackening, your job is to prevent black leaves from reappearance.
For that, here are some effective plant care strategies to prevent black leaves:
- Consider watering at the base instead of overhead watering. Do it in the early morning so that the water splashed on the leaves gets enough time throughout the day to dry out.
- Whenever you are watering the plant, make sure to let the top few inches of the soil dry out. It can solve half of the problems and keep your plant healthy.
- To check the soil moisture levels, use your finger or moisture meter.
- Place your plant where it can get bright, indirect sunlight. A west or east-facing window works. You can also use Venetian blinds or sheer curtains to filter the light and reduce the intensity.
- Use a well-drained and fertile potting mix as per your plant’s needs. Organic fertilizers like compost and bone meal can prevent deficiency and overfeeding.
- If the soil’s pH levels are high or low, add garden lime or gypsum to neutralize it.
- Correct fertilizer involves using a balanced fertilizer containing all the essential nutrients. Use it as per your plant’s needs.
- Use a humidifier in your room to receive the exact humidity levels your plant needs.
- If you are grouping your plants, make sure to provide adequate ventilation so that the leaves do not touch each other.
- Provide warm temperatures to your plants. Keep them away from cold drafts entering from open doors, winders, and ACs.
- Observe your plant to check out for pests and diseases. Occasionally, you can use neem oil as a mist. It will keep the pests and diseases at bay.
- Prune the dead, damaged, and infected leaves beforehand to prevent spores or pests from spreading. When conducting routine pruning, trim only one-third of the leaves to promote healthy growth.
- Use suitable plant pots. Choose the correct pot size with drainage holes. If you often make mistakes while watering, use self-watering pots.
Recommended Garden Supplies
Are you looking for a readymade indoor plant soil mix that you can open and pour? Check out rePotme. They offer a wide range of readymade soil premixes for all your indoor plants.
Several reasons can cause black leaves in indoor plants. Yellowing or browning is an initial symptom of most issues. Over time, the leaves will turn black, and other symptoms will be displayed, specifying the problem. Common reasons include overwatering, root rot, poor drainage, pest infestation, bacterial and fungal growth, exposure to cold drafts, and low humidity.
Some unlikely causes are nutrient deficiency, over-fertilization, underwatering, and sunburn. Look out for the symptoms the leaves display when they are under stress to diagnose and treat the problem correctly.
As a houseplant parent, observing the plant’s behavior regularly can help you identify the problem at the first stage and treat it quickly. Do not water or fertilize more than what your plant needs, provide indirect sunlight, avoid cold drafts, maintain average humidity, and ensure a sound drainage system.
Will my plant die if the leaves turn black?
Leaves turning yellow, brown, or black are signs of stress, and if left unaddressed, it can lead to the plant’s demise. Please find the cause and fix it to prevent your plant from dying.
Should I trim the black leaves?
You must trim the leaves whose half portion has discolored before providing any treatment or care. If you don’t, the plant will use its resources to revive these leaves instead of growing new ones. It can weaken the plant over time.
Reference: Indoor plants Wikipedia