Why Are My Indoor Plants Leaves Turning Black? (Causes+What To Do)

Indoor plants are a delight for eyes and space when they are green and healthy. But if there is something wrong with your plant, then its leaves might start turning brown or black. 

Black leaves indicate that your plant is suffering for a while now. But what causes black leaves, and how can we get rid of them. Let’s find out!

Bacterial infection and temperature stress are primary causes of black leaves in indoor plants. Apart from these lighting problems, inadequate watering and low humidity also lead to black leaves in indoor plants. You need to identify the problems early on to save the plant from wilting.

The main thing to keep in mind is identifying the issue before applying all treatments you know. 

The following points will help you shed some light on how your care routines affect your plants or cultural conditions that are not favorable for them.

Please read further to clear all your doubts and understand the actual causes of black leaves in indoor plants.

Also read: 13 reasons why your houseplant is dying?

What causes black leaves on indoor plants?

Black leaves on houseplants are not caused in one day. It usually happens when we ignore a basic need of the plant for an extended period. 

Improper watering and lighting are the first few points you need to check. Other causes include improper fertilizing, diseases, temperature stress, and so on.

Improper Watering

Improper watering is one of the major causes of your houseplant’s leaves turning black. It can happen if house plants are watered too much or too little. 

Overwatering can lead to tips of leaves turning black and root decay. Underwater can make the leaves dry and dull. 

Under-watering can equally harm the plant’s health. It will dehydrate the entire plant, and the leaves start to turn yellow and brown, followed by the plant’s death.

Different indoor plants have different watering requirements. You need to make sure you take the right steps to water them right. The soil around the plant should be evenly moist and water the plant when the top two inches of the soil get dry.

Due to overwatering, the plants suffer from water and nutrient deficiency. In addition, too much watering submerges the root ball and causes root decay, which affects the plant’s entire system. 

The roots and stems cannot supply the water and nutrients, and the plants don’t get enough water and nutrients, and the leaves turn yellow and black.

Also read: How long can houseplants go without water? (with 25 examples)

Lighting Problems

Too much light or direct sunlight are also the causes of black leaves or tips of leaves turning black. If the light is too strong and other cultural conditions are also not in favor, the plant leaves are the first ones to turn black.

If the plant is suffering from a lack of moisture due to strong sunlight and improper watering, the leaf tips start turning black due to this stress. 

Even low lighting can also put the plant under stress. The plant cannot produce its food correctly, the photosynthesis process slows down, and the leaves lack the energy to maintain their color, which leads to black leaves. 

Also read: Can Indoor Plants Get Too Much Light?

Temperature Fluctuation

Indoor plants usually prefer constant moderate temperature levels. A sudden temperature rise can shock the plant, leaching out the moisture from them, leading to black leaves. 

The leaves shrivel and turn brown initially, but continuous moisture loss and ignorance can lead to black leaves.

Even moving plants from one place to another can stress them due to sudden changes in temperature levels around them. If the new conditions are very adverse for them, then the leaves might wilt and turn brown and eventually black.

Keeping indoor plants near frosty windows or heating systems can also damage the leaves. Indoor plants, when moved outdoors improperly, leaves show signs of distress.

Black leaves or black margins on leaves of your houseplant usually occur when the planters ignore the signs of stress for a long time. The plant gives many signals through their leaves turning yellow, brown and eventually falling off.

Improper Fertilization

Every plant owner wants their plant to grow fast and bushier, due to which they end up fertilizing more than required. 

However, fertilizing more frequently or using an inadequate dosage can burn the roots and lead to black leaf tips or entire leaves turning black.

If we fertilize the plant with excess dosage, the plant will quickly process it, and the nutrients are absorbed faster than usual. 

The plant will not be able to handle excess nutrients at once, which causes fertilizer burn.

Inadequate dosage can cause a lot of damage to the entire plant. The leaves are the first ones to show the effect of over-fertilization. 

This doesn’t mean under fertilization is right; lack of nutrients can make the plants weak and affect their growth.

Also read: Should I Fertilize My Indoor Plants in The Winter?

Fungal and Bacterial Diseases

Fungal and bacterial diseases can be caused by several reasons such as overhead irrigation, poor ventilation, low lighting, and keeping the leaves wet. 

The leaves first have yellow freckles on the undersides due to bacterial diseases. That, when left untreated, leads to black leaves. Even the stems of your houseplants shrivel and turn black as a result of bacterial diseases.  

If your houseplant is suffering due to fungal disease, there will be black spots on the foliage that increases in size with time and form blotches and parches. 

If we soak the leaves every time we water the plant, it will lead to bacterial leaf spots due to water sitting on the leaves for longer durations. The leaves are likely to black spots due to this.

Infected Cuttings/Plants

The plant you newly bought may be already contaminated with plant disease. For example, some plants with bacterial leaf spots and stem rot cannot be cured and need to be dumped ultimately.

The leaves of your infected plant will turn yellow, brown, and black no matter how much you take care of them. No amount of right light, proper watering, and other conditions can cure them if they are not treated on time.

They can even infect the plants around them, so you need to take extra care of all plants around the infected plant. After that, you will hardly notice any growth, and the plant will slowly die.

Pests

Pests are also responsible for black leaves on your houseplants. Pests such as aphids, thrips, whiteflies, spider mites are prevalent to attack your indoor plants.

Most of these pests are tiny that cannot be seen through naked eyes. They suck on plants sap, damage the roots, due to which the leaves lose their vitality and color.

How do you fix black leaves on plants?

If your indoor plant has black leaves, you cannot just sit and watch them die. They need to be provided with correct lighting, humidity, and temperature.

You cannot help those leaves that have already turned black, so you need to prune them. However, we can save the other leaves and parts of the plant from turning black. 

We have discussed the relevant points for treating and preventing black leaves in your plant below.

Watering Adequately

Water your indoor plants through the soil instead of soaking the leaves. Let the soil dry out before watering them. You need to keep the soil around the plant evenly moist and not soggy.

The best way to check the soil’s moistness is by digging a finger or skewer in the soil up to 2 inches. 

Then, take out the finger/skewer, and if the soil feels damp or the soil is sticky to the finger/skewer, you need to wait for the soil to dry.

During winter, planters often tend to overwater their house plant, which can cause root rot. 

Even if the soil seems dry from the top, some houseplants like their soil will dry from within. Always check the soil moisture before watering them to avoid this situation.

Fixing Lighting

Houseplants are usually sensitive to direct light, they can take a few hours of direct light, but in the afternoon sun, the leaves can burn. 

In addition, the plants may lose their moisture, due to which the leaves wither, turn yellow, and then black.

Each plant has different requirements. You need to examine and watch your houseplant to know how much light is good for them. 

Keeping them in bright indirect light is the safest option to avoid any stress and leaf burn.

Even low light can harm the plants; the leaves cannot develop properly due to lack of energy, leading to discoloration of the leaves. 

It also doesn’t mean that you move your plant from a shady spot to the full sun at once. That can shock the plant and possibly lead to their death.

Move your indoor plant from one spot to another by increasing 1 hour every day. Gradually they will acclimate to the lighting and will not get stressed.

Fixing Temperature 

Houseplants fail to resist the danger of heatwaves, temperature changes, so you need to protect them from such conditions as much as you can.

Keep the temperature level between 60–75°F as most of the houseplants prefer a warm and humid atmosphere.

Temperature levels below 75°F can be harmful to your plant’s health. Please keep them in proper ventilation and away from frosty windows. 

Cold drafts, vents, and other heating systems can damage the leaves and the plant’s health. 

Fertilizing Adequately

Fertilizing indoor plants is essential to provide sufficient nutrients, but overfeeding can cause more harm than good. 

To get rid of the salt build-ups due to overfeeding, water the plant thoroughly to leach the accumulated salt in the soil through the drainage holes.

Reduce the amount of fertilizer by diluting the dosage to half and fertilize in longer intervals than before so the leaves can regain their color and new leaves are healthy.

Always water your plant before fertilizing them to avoid any heat in the soil and roots. Also, avoid fertilizing from autumn through winter as they are in dormancy at this time of the year.

Treating Fungal/Bacterial Disease

You can treat fungal/Bacterial diseases by applying fungicide spray to the plant. But, first, make sure you have docked the infected stems and leaves. 

Then, you can use copper fungicides by diluting them to treat the disease to get faster results. 

Fix poor ventilation and avoid grouping of plants to withdraw further spread of the disease. Do not wet the leaves of the plants at all and water them in the morning sun to allow the leaves and plants to dry quickly.

Do not prune the plant when it is wet, and use sterilized scissors to prune them to avoid spreading the disease.

Fixing Infected Cuttings/Plants

Infected cuttings are among the biggest reasons for a plant’s poor health and spread the disease to another plant without you even knowing. 

You may be busy fixing other conditions for and around your infected plant and may not know that they have already entered your space with diseases.

If you have recently got any plant, immediately quarantine them from other plants. Please treat them with fungicide spray till the problem persists. Buy plants from reliable stores to decrease the chances of infected plants.

Take cuttings from healthy plants and use sterilized scissors. Please do not use these scissors for other plants before sterilizing them and keep the cuttings in disinfected containers.

Treating Pests

Treating pests on your houseplants is a task and will take some time to accomplish. However, we have put together all the effective ways to treat pest infestation.

Neem oil

Start with isolating your houseplant to avoid other plants getting infected. Neem oil is one of the best non-chemical methods to treat pests without harming the plant.

Dip a cotton ball in a neem solution and apply it to one of the infested plant leaves. This is to assure that the plant doesn’t harm from the neem oil.

If the plant doesn’t reveal any issue, then apply it to the entire plant and leave it overnight. Do this once a week for complete eradication of pests.

You can also make a neem oil solution and use a mister to spray it all over the plant once every week. 

Neem oil helps to treat as well as repel bugs without harming your plant. They work well to battle versus powdery mildew, kill eggs and larvae of pests, and essentially decrease their population.

Pyrethrum Spray

Pyrethrum spray is a natural pesticide that has pyrethrin as an active agent. As it is plant-derived so it is safe for houseplants and will not cause any harm to them.

They can kill and repulse pests like aphids, spider mites, flies, etc. They can be used as a preventative measure to prevent pests attack.

Mix 2-3 spoons to 1-gallon water and pour it in a spray bottle. Now spray all over the plant, especially on the undersides of the leaves, and leave it overnight. Repeat once a week till the plant is completely relieved from pests.

Soapy Water

Soapy water will also help to treat moderate pest infestations on your houseplants. In addition, insecticidal soaps are safe for use on your houseplants.

Wash the infested plant with mild insecticidal soap or mild soap to kill any pests on contact. Rinse the pot and tray with soapy water as these stubborn pests can be hiding in there.

Rubbing Alcohol

You can use rubbing alcohol to treat pest infestation. Then, soak a cotton swab and apply them on the pests and kill them.

Yellow Sticky Traps

You can use yellow sticky traps to catch and destroy little flying pests in houseplants. They will also keep other plants from these flies and are non-toxic.

Be sure to follow the above-given methods simultaneously with these traps for getting free of pests on plants’ leaves and stems. Unfortunately, these traps cannot kill the eggs on the plant, so you need to use other methods too.

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Ref: Preventing, Diagnosing, and Correcting Common Houseplant Problems, Pest and Disease Problems of Indoor Plants, Environmental Problems of Indoor Plants