There are tens of thousands of unique plant species, each featuring unique characteristics. However, one common feature among all plants is the tendency of their leaves to turn black.
Black leaves are a warning signal that plant owners must never ignore. So if your plant leaves are turning black, read on to learn the possible reasons and solutions!
Why do Plant Leaves Turn Black?
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Black leaves on plants can be displeasing to look at and take away from the overall appeal of your plants. In most cases, plant leaves turning black is always a sign of an underlying issue. Here are a few reasons why your plant’s leaves may be turning black:
Root Rot
Root rot is a major culprit behind a plant’s leaves turning black. Root rot can be deadly for your plant. Therefore, taking immediate action is critical to saving the plant from death.
Dark spots or entire chunks of plant leaves turning yellow, dark brown, or black, maybe a possible sign of root rot. If you notice these changes in your plant, inspect for other signs of root rot.
You want to look for signs like a rotten foul smell from the soil, mushy leaves and stems, and reddish brown roots. Next, gently remove your plant from its pot to inspect the roots and examine them for reddish brown or black parts.
If you notice root rot, immediately cut off the damaged roots with a clean knife and re-pot your plant in a fresh new potting mix.
Pro-tip! Instead of using any soil, use a proper potting mix made specifically for the plant species.
Direct Sunlight
Most new plant owners think that the more direct sunlight their plants receive, the better it is for them. However, direct sunlight can be a reason behind a plant’s leaves turning black.
Although sunlight is critical for plants to undergo photosynthesis — too much light, especially direct light, can scorch your plants and cause them to turn black.
Therefore, you must always research how many hours of direct sunlight your plant prefers before exposing it to direct sunlight for long hours of the day.
Although some plants may thrive in direct sun exposure, others may prefer indirect sunlight. Researching a plant’s light requirements before purchasing it can allow you to ensure you are providing it with optimal lighting conditions.
Too Much Fertilizer
If you are a plant enthusiast, it can be tempting to fertilize regularly to make the plant grow faster. However, excessive fertilizer can cause a plant to develop a condition known as fertilizer burn.
This condition can sometimes exhibit itself by making your plant’s leaves turn black. The best way to avoid this is to research the fertilization needs of your plant’s since every plant can have different fertilizer requirements.
Moreover, when fertilizing your plants, dilute the fertilizer in water to minimize its harshness. Using little water with fertilizers can also cause blackened leaves.
Important note! Opt for organic fertilizers. Store-bought fertilizers can have harsh chemicals that can significantly harm your plants.
Lack of Fertilizer
Although excess fertilization can lead to black leaves on plants, the absence of fertilization can lead to similar issues. When your plant lacks nutrition, its leaves can go from healthy green to brown, eventually turning black and dying.
A lack of fertilizer can also make your plants more susceptible to diseases like root rot or powdery mildew — which can also cause the leaves to turn black.
Fungal or Bacterial Diseases
Blackened leaves can also sometimes signal fungal diseases and bacterial infections like sooty mold and blight of beans. If you suspect your plant may have a bacterial or fungal disease, look out for the following symptoms:
Fungal disease symptoms
Powdery mildew
Stem rust
Sclerotinia (white-colored mold)
Yellow leaves
Bacterial disease symptoms
Spots on leaves with a yellow halo
Crown gall
Canker
If you notice any of these symptoms in your plants, take your plant to a plant doctor or get advice from experts at your local nursery on how to treat it.
Neem oil works well in the management of certain fungal infections in plants. You can apply neem oil on a cotton ball and rub it on the affected leaf to help your plant recover.
Wrong Soil
Every plant has different soil requirements. Some plants enjoy a sandy soil mix, whereas others prefer clay soil. If you plant a specie of plant that thrives in sandy soil in a clay soil mix, then your plant is likely to convey its displeasure through black leaves.
So when you purchase a plant, question the experts at the local nursery about its soil requirements or conduct thorough research online to get answers.
Pest Infestation
Although many plant species are not highly susceptible to pests, they may become more prone to getting developing pests like mealy bugs and spider mites due to certain environmental factors.
If you miss pest infestations in the early stages, they can cause significant damage to your plants, leading to blackened leaves. The best way to avoid this is to examine your plants for pests regularly.
Poor Ventilation
Poor ventilation can be another factor that may cause a plant’s leaves to change color. This issue usually occurs in houseplants that are kept in rooms that lack ventilation.
Like humans, plants require an optimal amount of oxygen to thrive. Keeping plants in a room without proper air circulation may impact their breathing ability and lead to color changes.
Under watering
Every plant has a specific amount of water requirements, with some plants being able to thrive for weeks without water and others requiring irrigation several times a week.
Underwatering is a common mistake many plant owners make. In the early stages of under-watering, the leaves usually turn brown and shrivel. However, continued moisture loss can cause the leaves to eventually turn a black color.
The best way to avoid underwatering your plant is to study its water requirements and provide optimal water.
Furthermore, you should water your plants more often during the hot summer. Dipping two to three inches of your finger in its soil is the easiest way to determine if your plant needs more water. If the soil feels dry, your plant is ready for watering.
Temperature Stress
Temperature stress can cause a plant to suffer shock and develop black spots on its leaves. If you have an indoor plant species that thrive in warm temperatures, ensuring the plant receives that environment all year round is critical to its health.
If you place the plant near air conditioning or a window blowing in cold drafts of wind, then it is likely to show signs of temperature stress. Moreover, leaving plants outdoors in freezing temperatures can cause severe stress and eventually kill them.
Overwatering
Overwatering is a common reason behind plant death. Plant owners often overwater their plants, leading to blackened leaves. This is because when you overwater a plant, it affects its ability to take in oxygen.
If you think your plant leaves are turning black due to excess water, stop watering your plant for a few days until the soil turns completely dry.
Overhead Irrigation
Some plant owners may wet the stems and leaves of their plants during watering as a means to clean their plant leaves. However, this may be one reason behind their plant leaves turning black.
Some plants do not like excessive moisture and may begin to get black spots if you continue to wet the whole plant during watering. To avoid this, water your plant from below, ensuring you only wet the soil.
Preventive Measures to Avoid Plant Leaves from Turning Black
By following the preventive measure below, you can keep your plants in a healthy condition and avoid issues like blackened leaves:
Choose Pots with Drainage Holes
As discussed above, overwatering is a common reason most plant leaves turn black. One way to avoid drowning your plant in water is to purchase pots with drainage holes.
When you water your plant, the excess water will drain through the drainage hole, which can significantly lower the damage from overwatering.
Additionally, empty your cache pots on time to prevent the plant pot from sitting in water for a prolonged period.
Keep Infected Plants Separate
Keeping infected plants separate is critical to prevent your plants from developing black leaves due to pest infestations and fungal or bacterial infections.
Keeping an infected plant with your other plants may make your other plants more susceptible to developing similar conditions and make your entire plant collection prone to a severe pest or disease breakout.
Regularly Inspect your Plant’s Health
Inspecting your plants’ health regularly can help you spot issues like yellowing leaves and black edges in the early stages and manage them before they cause significant damage.
If you notice changes in the appearance or tone of your green leaves, try to get to the bottom of the issue by considering the factors discussed above.
Create a watering Schedule to Avoid Improper Watering
Creating a watering schedule can help you avoid over and under-watering issues. You can do so by downloading an app like Waterbot that helps remind you when to water your plants or by setting the alarm on your phone.
Moreover, always check the first few inches of soil when watering your plant to ensure it’s dry. This is because seasonal changes can cause your plant to dry out too quickly or slow drying.
Treat Pest Infestations with Natural Pesticides
Most people turn to store-bought pesticides to treat pest infestations in their plants. However, these pesticides are made with harmful chemicals that can cause damage to your plants. Natural pesticides like neem oil can be a great alternative to store-bought ones.
Pro-tip! Opt for horticultural oil if you don’t want to use a natural pesticide. This commercially sold pesticide is distilled and filtered to eliminate harmful compounds that may damage plants.
Always Filter Out the Sunlight
Unless the specie of plant you have prefers direct sunlight, filtering out the sunlight is always a great way to prevent heat stress. You can add light curtains to your windows to protect your indoor plants or place your plant far from the window.
For outdoor plants, try to add shade by installing outdoor shades like shade sails. You can also place smaller plants under the shade of larger trees.
Avoid Extreme Temperature Fluctuations
As previously discussed, plants leaving turning black may occur due to extreme temperature changes. So you want to avoid moving your plant to areas with a sudden drop or increase in temperature.
During winter time, it is best to bring some plants that may not thrive in cold weather indoors. Doing so will help prevent your plants from developing fatal conditions like frostbite.
Dispose of Infected Cuttings Properly
Sometimes you may end up with all your house plants getting infected due to contact with infected cuttings. These pest breakouts can make your plant’s leaves turn black and be incredibly difficult to eliminate.
To avoid this, dispose of cuttings from an infected plant properly. You can do so by sealing the cuttings in a plastic or ziplock bag and throwing the bag in a trash can.
Bottom Line
Issues like, overwatering, under watering, poor ventilation, fertilizer burn, direct sunlight, and root rot may be why your plant leaves may be beginning to turn a black color.
Knowing why your plant leaves may be turning black can help you pinpoint the reason for color changes on your plant leaves and take the necessary steps to reverse them.
You can also use the preventative measures discussed above to avoid blackened leaves on your plants and maintain healthy green leaves all year round.