Why Are My Peace Lily Leaves Turning Yellow | Causes & How to Fix

Peace lilies, Spathiphyllum wallisi, are easy-to-grow, low-maintenance houseplants that produce elegant white flowers and deep green foliage. This species is listed at the top of NASA’s clean air list and can live for several decades if properly cared for.  

When your plant’s foliage is looking anything other than perfectly green it can feel frustrating and even baffling when you’re sure you have been caring for it correctly. In this article I’ll be describing the causes of peace lily leaves turning yellow and how to quickly fix it.

Understanding Why Leaves Turn Yellow

The yellowing of leaves is called chlorosis and occurs when environmental factors trigger issues within the plant’s chlorophyll cells that house photosynthesis and are responsible for the plant’s green color. When these processes are disrupted, pigments fade to yellow, and leaves begin to die. 

Symptoms and Causes of Peace Lily Leaves Turning Yellow

The most common environmental factors that cause the yellowing of peace lilies are watering issues, nutrient deficiencies, improper temperature, low humidity levels, pests, and diseases.

Depending on the reason, your peace lily can have a number of different symptoms ranging from just yellow leaves to yellow leaves that droop or drop and even faded leaves that later develop brown patches.

Before taking action, it’s worth observing all of your plant’s symptoms as this will provide you with insight into how best to fix the problem.

Peace Lily Leaves Yellow and Drooping

Yellow, droopy leaves are most often a result of improper soil moisture. When plants are repeatedly over-watered root rot can develop. This shows above the soil level firstly as droopy leaves that can quickly fade to yellow.

Underwatered Peace Lily
Underwatered Peace Lily with the beginnings of yellow leaves

Prolonged soil moisture level issues will also eventually also lead to nutrient deficiencies and unfortunate leaf drop.

Two further common reasons that peace lilies develop yellow, drooping leaves are when the plant becomes root-bound and also after re-potting.

Peace Lily Leaves Turning Yellow and Falling in Summer

Nutrient deficiencies are the most common cause of yellowing leaves during the growing season. The four most commonly deficient nutrients and their symptoms are the following: 

Nitrogen deficiencies cause yellowing of the entire leaf surface starting in the older leaves, followed by severe wilting and leaf drop. This particular deficiency is most likely to occur when peace lilies are flowering. 

Potassium deficiencies cause the yellowing of leaf tips and edges, starting in older leaves. Often occurs after prolonged periods of underwatering. 

Iron deficiencies cause the yellowing of leaves while the veins remain green, or interveinal chlorosis. Often produced by pH imbalances in alkaline soil rather than the absence of iron.

Magnesium deficiencies also cause interveinal chlorosis of the leaves but usually include a reddish-brown hue.

Peace Lily Leaves Yellowing with Dry Brown Edges

Direct sunlight or extremely low relative humidity levels are common reasons peace lily leaves turn yellow, curl, and brown on the edges. 

Another common reason peace lily leaves turn yellow and develop brown tips is from using tap water. Chlorine, hard water, or pH imbalances in tap water damage peaceful lily roots, which leads to nutrient deficiencies and eventual plant death. 

Yellow leaves with browning leaf tips and margins can also be caused by salt toxicity from over-fertilization, which leads to stunted growth and defoliation from plant shock.

Peace Lily Leaves Turned Yellow with Brown or Yellow Spots

Pests and disease are the most common causes of irregular brown or yellow spots on struggling peace lily plants. 

Fungal diseases, like root rot, commonly cause lower leaf yellowing, dark brown spots, wilting, and stunted growth. While spider mites cause tiny yellow dots and webbing on the leaves of your peace lily plants. 

How To Fix Peace Lilies with Yellow Leaves

Once you have determined the cause of your peace lily’s yellowing leaves, you need to quickly implement one of the following methods to save your beloved plant. 

Overwatering

If over-watering has occurred, drain the catch tray, refrain from watering, and allow the soil to dry.

Once the soil is dry, feed a liquid a supplemental fertilizer since leaching of nutrients has likely occurred. Then only water when the top 1 inch of the soil is dry. 

Underwatering

If under-watering has occurred, give your peace lily enough water to fill the entire container and let drain. Repeat 2 – 3 times over the next few days or until your peace lily plant perks back up. 

Using Unfiltered Tap Water

If damage from unfiltered tap water has occurred, then flush the container 2 – 3 times with distilled water. If the salt build-up is too severe, then transplantation to new soil will be necessary to stop any further root damage. 

Nitrogen Deficiency

If you suspect a nitrogen deficiency, then add 1-inch of top dress, and evenly water to allow the leaching of nutrients into the soil. My preferred top dress mix is is a combination of 1 part organic potting soil mix and 1 part worm castings.

Potassium Deficiency 

If you suspect potassium deficiencies, then add  ½ inch of composted manure or worm castings to the top of the soil once per month during the growing season. Evenly and thoroughly water.

Beware that those applications of manure can make the soil pH more alkaline, so adjust to a slightly acidic pH between 5.8 and 6.5, if necessary. 

Iron Deficiency 

If the soil pH is above 7, then lower it by adding 2 tablespoons of white distilled vinegar to 1 gallon of water and use every third watering. Then treat the iron deficiency with a foliar application as the soil pH slowly adjusts. 

According to Utah State University, foliar applications of iron chelates or a 0.5% solution of ferrous sulfate are effective means of iron deficiency treatments for herbaceous plants. Repeat treatments, as necessary.

Magnesium Deficiency 

If magnesium deficiencies are suspected, then sprinkle Epsom salt on the soil, using 1 teaspoon of Epsom salt per foot of height. 

Continue to water as usual and only use when necessary to avoid salt build-up in the soil.

How to Fertilize Peace Lilies

Use an NPK ratio of 1:0.5:1 every 2 weeks during the spring and summer. 

This method limits toxic salt build-up while supplying necessary nutrients to your highly efficient peace lilies. Since they are tropical plants and not true lilies, peace lilies require less phosphate than other species that haven’t evolved with the deficiency in their native soil.

Over-Fertilizing

If over-fertilization has occurred, flush with enough fresh water to fill the entire container, and repeat 2 – 3 times for a week. Refrain from adding additional fertilizers until signs of deficiencies reappear. 

If the salt build-up is severe, then transplant into fresh soil. 

Transplantation

Re-potting every 2 – 3 seasons will increase the lifespan of your peace lilies but they can be prone to transplant shock while they acclimatize once they have been re-potted or after propagation

To limit transplant shock, use a container that is only twice as large as the root ball and water thoroughly to eliminate any air pockets. 

Use a well-draining and slow-drying soil mixture to ensure your peaceful lily’s roots remain moist while limiting the chances of root rot fungus. My favourite soil for peace lilies is as follows: 

  • 1 Part: Organic Potting Soil
  • 1 Part: Coco Coir
  • 1 Part: Fine Potting Bark or Perlite 
  • 1 Part: Worm Castings

Excessive Sunlight Exposure

As tropical understory species, peace lilies require 7 – 9 hours of bright but filtered sunlight. 

If damage from the excessive sun has occurred, then immediately relocate and water thoroughly. Trim any brown leaves once the peace lily has fully recovered. 

Rapid or Frequent Temperature Fluctuations

Peace lilies prefer temperatures between 65 – 75 degrees Fahrenheit, with night-time temperature drops of only 10 degrees. 

Relocate your peace lily at least 9 feet from the main doors and heat sources. Unless completely dry, wait 2 days to water or feed to limit any additional stress to your peace lily.

Peace Lily Pest Infestation

Spider mites and other common household pests can be prevented and treated with premixed all-natural essential oil sprays that contain neem and lemongrass. Use as directed. 

Cylindroncladium root and petiole rot, Cylindrocladium spathiphylli, is a serious fungal disease that destroys the entire root system within a few months if not treated with benomyl or triflumizole fungicides. 

Citations

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.