Peace lily (Spatiphyllum) is a popular choice among ornamental plant lovers. However, difficulties in establishing and maintaining good conditions for growing this plant lead to certain problems. The blackening of the leaves is one of them.
In this article, you will learn about the various causes of the said problem. We will also give you a list of solutions and preventive measures for each cause.
Peace lily leaves turning black or having black spots due fungal infections and the presence of pests also lead to this problem. Other causes are overfertilizing, improper amount of light, low percentage of humidity and improper choice of potting mix.
Causes Why Peace Lily Leaves Turn Black
Plants belonging to the aroid family can be very demanding when it comes to water and humidity.
As the natural habitat of peace lily is a tropical rainforest, you have to imitate those conditions in your own home. This can be quite challenging.
You can achieve an environment that your peace lily would prefer by setting optimal temperature, applying a balanced amount of water, and using water with good quality.
Here is the list of possible causes of black spots on leaves of your Peace lily :
This implies both underwatering and overwatering. Rainforest is a place where rain showers are a common occurrence.
Thus, the peace lily doesn’t tolerate underwatering. If you forget to water your Peace lily, you can expect the leaves to shrivel and die very soon.
The roots won’t have enough water to transport to other parts of the plant when the soil is too dry.
It also affects the carrying of micronutrients needed by the plant water proper growth and development.
This lack of hydration and micronutrients is the reason why peace lily has that shrunken appearance.
On the other hand, overwatering can lead to even more disastrous consequences.
If you overwhelm peace lily with large amounts of water, the soil will become soggy. The root environment becomes anoxic, and the roots get suffocated.
In a nutshell, the roots die and lose their normal functions. As a result, nutrients and water are not transported on the upper portions of the plant.
How to Fix This Problem?
For proper watering of the peace lily, consistency is the key. Don’t let the soil become crusty and dry neither make a stinky swamp in your planting pot. You should keep the soil moist but not wet.
If some leaves decay, cut them off by using sterilized scissors. This will prevent unnecessary transfer of nutrients to unproductive leaves.
Set Up A Good Drainage System
To avoid waterlogging, make sure drainage holes are present and functional. Ensure that your peace lily doesn’t sit in a saucer filled with water for too long.
The drainage capacity of the soil mix is also an important factor to consider. So select a good drainage soil for your peace lily.
Mineral Deposits (Water Quality)
Tap water in households usually contains significant amounts of chloride and fluoride, bicarbonates, and other impurities.
Your Peace lily won’t respond positively to such quality of water. Those compounds can lead to salinization or even acidification of the soil.
The salt build-up in the potting soil will cause inefficiency in supplying water to the plant. Salts in the soil tend to absorb water making it unavailable to the root and plant uptake.
Also, dissolved sodium and chlorine ions displace other essential nutrients in the soil, which leads to a deficiency. (Source: University of Massachusetts Amherst, The Center for Agriculture, Food, and the Environment)
As the plant doesn’t receive nutrients such as potassium, magnesium, and phosphorus, the plant will show changes in leaf color. Some leaves turn yellow, brown, and purple with some black spots present.
How to Fix This Problem?
Filter the Water
If you used to supply your peace lily with tap water, you will probably notice dark stains on the leaves very soon.
One solution is to filter tap water to reduce the concentrations of chloride and fluoride. Also, consider using distilled water.
If no filter is available, you may just let the water sit for 24 hours first before you use it. Chemicals like chlorine will simply evaporate leaving the water less harmful.
If you get the chance to collect rainwater, that would be the best water for your plants.
You can save water in a big container and save it for future use on your plants.
Fungal Leaf Spot (Cercospora, Phyllosticta or Rhizoctonia)
Black spots on the leaves are not only caused by improper watering or quality. You must know that moist conditions invite fungus.
Wet potting soil and foliage definitely make such an ideal condition for them.
If you notice dark grey-colored circles that are yellow in the middle, then your peace lily may be infected by Cercospora fungi.
Necrotic leaf spots with reddish or purple borders are caused by a fungus from the genus Phyllostica.
If spots on your peace lily are yellow with alternating light and dark concentric rings, then it is being attacked by Rhizoctonia invaders. (Source: Louisiana State University)
How to Fix This Problem?
Use Baking Soda
This method is less destructive to plants. Baking soda is a good antifungal agent and also non-toxic. Dissolve one teaspoon of baking soda into one liter of water and pour the mixture into the spray bottle.
Apply this solution to the infected parts of the peace lily. Repeat application to completely remove all fungi traces.
Use Pathogen-Specific Fungicide
You have to apply a fungicide specifically for a pathogen that has attacked peace lily leaves.
Pay attention to the prescribed amount and concentration of fungicide solution you use.
Fungicide treatment for Cercospora leaf spots should be used once only to avoid fungal resistance.
Check each leaf and cut off the damaged ones to prevent the infection from spreading further from the infected areas.
Sometimes the cause of the problem is hiding beneath the surface of the soil. Wilting of the entire plant is a sign that there’s a stinky and moldy root under the surface.
Rotten roots normally turn from white color to brown and black. Waterlogging and poor drainage system often causes root rot.
Cylindrocladium fungi are the most common root rot pathogens. Once the roots start rotting, the leaves turn mushy with colors changing from yellow to brown to black. (Source: The Pharma Innovation Journal, 2017)
How to Fix Peace Lily Root Rot
Repot the Peace lily
If the root is partially rotten, you can still save your Peace lily. Remove the entire plant from the pot and remove excess soil from the roots by gently shaking.
Wash the root under a light stream of tap water or use the distilled water for that.
Cut off the rotten pieces with the sterilized scissors. Wrap the root with the newspaper and keep it out of the potting soil for several days to dry and ventilate.
Let the roots heal a bit to avoid further injury. Plant the peace lily into fresh potting soil.
Withhold Water for A While
Damaged roots need time to heal. It’s best to keep the water away from the plant for a while until it’s recovered.
When the plant has regained its vigor, you may gradually apply water to the soil. Make sure to keep it in moderation.
If any of the causes listed before are not the reason your peace lily leaves turning black, you should check if you have some uninvited guests such as mealybugs, scales, and mites.
Those insects often inhabit the leaves of peace lily for feeding and reproduction.
They chew and suck on the tissues creating damages on the plant like black spots.
How to Fix This Problem?
Shower The Plant
Try to shower the plant and let the water run lightly. Strong pressure of water can injure the plant. Light showers can wash away many pests.
Spray Homemade Solutions
You can create your own solution just by using insecticidal soap, neem oil, dishwashing liquid, and other household products available.
Dilute it to water and spray it on the plant. Most insects can get killed by those solutions.
Use Species-Specific Insecticide
If the other two options don’t help, try using insecticide specifically made for the species of the pest.
Don’t overdo when applying insecticide because it contains toxic chemical compounds. Always bring your plant outside whenever you spray insecticides.
Excessive amounts of fertilizer especially nitrogen increase the acidity of the soil. This results in chemical imbalance and impaired mineral uptake by the root.
Fertilizers include soluble salts that dissolve in water found in the soil. Fertilizers include soluble salts that dissolve in water found in the soil.
As salts build up in the soil, water becomes deficient creating a drought condition. Some essential nutrients such as iron, magnesium, manganese, copper, and potassium become unavailable for plant uptake.
Lack of those nutrients leads to leaf necrosis with some black portions, leaf tip burns, wilting, and even death of the plant. (Source: University of Massachusetts Amherst)
How to Fix Overfertilization
Wash The Salts Away
Leach the soil with distilled water to remove excess salts and other compounds from too much fertilizer.
Make sure that the drainage system is well to drain polluted water successfully. Try using alkaline water for neutralization of the low pH value.
In the tropics where peace lily belongs, the temperature doesn’t go below 25ºC (77ºF).
Peace lily couldn’t tolerate a too low temperature. It is not advisable to keep this plant in cold rooms.
Root loses its normal functions and leaves don’t evaporate well at chilling temperatures.
The whole metabolism is impaired thus leaves will start to wilt. Very soon, when the plant is thawed, you have black spots on the leaves as a result of cold injury.
How to Save Peace Lily From Cold Injury
Place in A Warmer Location
First, put the Peace lily in a warmer room. Don’t prune off decayed leaves immediately.
Those leaves will prevent further injury by insulating the plant. However, if there’s a bacterial or fungal infection, you have to get rid of those leaves.
Due to cold injury occurrence in winter months, prune off the damaged leaves carefully in the spring time to form a callus at the injury point.
However, the temperature in the room where you keep peace lily shouldn’t go below 15ºC (59ºF).
Peace lily loves places with a high percentage of humidity and couldn’t stand dry air for longer periods.
If you keep your Peace lily in a room with air conditioning, heat generators, and ovens, then blackened leaves shouldn’t be a surprise.
Dry air induces the heightening of transpiration rate. This causes the plant to lose more water than it receives.
The result is dehydration of the entire plant leading to a shriveled appearance.
How to Fix Humidity
Group The Plants
Increase the humidity by grouping peace lily with other tropical plants in the room. Being together like this, they form special microclimate with higher percentage of humidity.
Mist The Leaves
Mist around the Peace lily to create a fog of moisture which wraps leaves. You can do this around two times per week early in the morning.
Get A Humidifier
A humidifier does help in increasing humidity at home. If you have one, place it somewhere near your tropical plants including your peace lily. The added moisture will surely help the plant thrive.
This arum species is a shade-loving plant so avoid direct sunlight. Low light levels, on the other hand, can result in a pale color of the leaves.
This means that there’s a need to expose it to enough amount of sunlight, which provides energy for the sugar build-up.
Place under Bright, Indirect Light
Peace lily likes indirect sunlight the most. Place it in the bright room with large windows on the east side.
Also, try with LED bulbs to increase the light level because they don’t generate heat. (Source: University of Vermont, Department of Plant and Soil Science)
How to Prevent Blackening of Peace lily leaves?
Prevention is better than cure. If you read this text at the moment and you have a completely healthy, dazzling Peace lily with shiny, green leaves, then you should know how to avoid the problems mentioned above.
Stick with this article and find several ways how to evade the blackening of the peace lily leaves.
This is an important factor for normal growth and development. Water your peace lily once per week and dampen the soil everywhere equally. Increase water frequency when it’s hot and otherwise if it’s cold.
Choose The Right Type Of Soil
Soils with tiny grains tend to clump and compact together causing water to clog around the root environment.
Don’t pick clay soils at all. Potting mix with peat and vermiculite is the best choice for the plant.
Ensure Good Drainage System
Water must have a way to escape the pot. To avoid plant sitting in excess water, put styrofoam as the drainage layer under the pot. Also, you can poke the soil with a pencil to aerate the soil.
Handmade Compost Usage
You shouldn’t throw away the water in which you washed the vegetables and eggs or potato and carrot peel.
You can use these residues for your Peace lily supplementation with essential micronutrients.
Peace lily will love the domestic compost because they don’t have too many salts and detrimental compounds like commonly used fertilizers.
Pay Attention to Pot Size
If you grow a Peace lily in a small pot, water it more frequently with smaller amounts of water, since the small amount of soil dries quicker.
On the other side, a bigger pot means larger amounts of soil. If you chose a large-sized pot, water the plant less frequently with larger amounts of water.
Match Temperature And Sunlight
A warmer room with plenty of indirect sunlight is the best combination for a peace lily.
It is best if you can prove adequate temperature without heat generators because they reduce humidity in the air.
The optimal temperature for Peace lily is about 20ºC (68ºF). Large-sized windows will provide the proper sunlight.
Why Are My Peace Lily Leaves Turning Brown?
Most often factors for this are improper watering, which implies underwatering and overwatering, bad light conditions (exposure to direct sun rays or low light), and too much fertilizer.
How Do I Know If My Peace Lily Is Dying?
Droopy leaves which are starting to lose its healthy, green color and turning yellow and brown are the most obvious signs of peace lily dying.
Why Are My Leaves Turning Yellow And Brown?
Water stress which includes both underwatering and overwatering might change the green color to yellow and brown.
Also, a lack of nutrients such as iron, manganese, and, zinc can cause chlorosis of the leaves. Keeping peace lily in dark rooms interferes with photosynthesis leading to etiolated (pale or yellow) leaves.
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