Why Are My Peace Lily Leaves Turning Yellow (Spathiphyllum wallisii)?


There are many different reasons for your peace lily leaves turning yellow. It is often a result of environmental conditions and can usually be fixed with some love and attention. When your peace lily is healthy, the leaves should be a dark and vibrant green.

Common causes of peace lily leaves turning yellow

Sunburn

Peace lilies can thrive in conditions with very low lighting. They naturally grow on the ground of tropical forests, meaning that they have adapted to thrive in the shade. If you keep them completely in the dark then this can cause the leaves to turn yellow, however, this is uncommon.

Too much light is far more likely to result in yellow flowers. Direct sunlight for an extended period of time will scorch and bleach the leaves. This can make them turn yellow or even brown. To remedy this, all you need to do is move them to a spot with more indirect sunlight.

Overwatering

This is probably the leading cause of yellowing leaves on peace lily plants. It can be caused by giving your plant an excessive quantity of water, or by watering too frequently. You should allow the top inch of the soil to dry out completely before watering your peace lily again.

Overwatering could also be caused by having your peace lily in an unsuitable soil mix. The mix you use must be well-draining and should contain a compound such as perlite to assist with drainage. Your plant pot should also have some drainage holes in the underside to allow excess water to drain away from the roots.

Overwatering can cause root rot. This is caused by the roots constantly being submerged in stagnant water. This can also reduce oxygen levels in the soil, essentially suffocating the roots of the plant.

Underwatering

Generally speaking, it is safer to slightly under-water your peace lily than it is to overwater it. You will notice the plant drooping dramatically if it is thirsty, giving a clear indication that it is watering time. If you leave the plant being thirsty for too long, this can cause the leaves to turn yellow. This can often be fixed by giving your plant some water and keeping it on a more regular watering schedule.

Water quality

The water from the taps in your home contains a number of chemicals to make it safe for humans to consume. The most notable of these is chlorine. If chlorine compounds enter the peace lily, they can begin to bleach areas of the leaves. This results in the leaves turning yellow.

There is a simple solution to this. You can add a few drops of a dechlorinator designed for aquariums to remove the chlorine instantly. Alternatively, you can collect rainwater and use this to water your houseplants. You can also filter the tap water, use distilled water, or allow the tap water to sit overnight. This allows the chlorine gas to escape from the water, making it safer for your plants to drink.

Personally, I allow my water to stand at least overnight, and I have no problems with my peace lilies.

Age

As your peace lily ages, some of the original leaves will begin to yellow. This is a natural part of aging, and you should not be worried if this is happening to your plant. The leaves will dry up and fall off, being replaced by new growth.

Cold temperatures

Peace lilies thrive at standard room temperatures, between around 68-85oF. This means that if you are comfortable in your home, your peace lily probably is too. They are not good at handling the cold and do not react well to being placed in a draughty area. Temperatures below 45oF will result in the leaves yellowing and potentially falling off.

Pests

Pest infestations can sometimes lead to leaves turning yellow. Common pests include mealy bugs and red spider mites. Yellowing can occur when the infestation has grown to become quite large. By this point, you are likely to be able to spot the actual bugs roaming about.

Treatment with a natural insecticide based on soap or neem oil is recommended.

Diseases

The 2 main diseases that can cause yellow peace lily leaves are Cylindrocladium spathyphylli and Phytophthora parasitica. These are fungi found in soil that can damage the root system of your peace lily.

If you are seeing yellow leaves as a result of these fungi, it is likely too late to save the plant. The best way to prevent them is to be sure you are not overwatering.

Nutrient deficiencies

If there are not enough nutrients in the soil for the plant to uptake, this can stunt the growth and inhibit the health of your peace lily. All plants require nitrogen to grow healthy, green leaves.

If the leaves of your peace lily are yellow, but the veins have stayed green, this is likely due to an iron or magnesium deficiency. Sometimes sunburned leaves will also appear like this, so try and rule this out as an option.

If you suspect a nutrient deficiency is the cause of your yellowing leaves, we recommend feeding your plant with a specially formulated fertilizer. Dilute this according to the instructions on the packaging and feed it to your plant at regular intervals. This should be done throughout the growing season, from early spring until late fall.

Transplant shock

If you have recently repotted your peace lily and have since noticed the leaves turning yellow, do not worry. Transplanting is a stressful time, and this is their way of telling you it’s been hard on them. They will likely recover in no time with proper care.

Should you prune off yellow leaves?

Yes, you can prune off yellowed leaves. They will never turn green again, and it is advised that you do prune them off. You should ensure you use a sharp blade such as scissors or gardening shears to do this, as this minimizes the damage done to the plant. The blades must be sterilized before use to prevent new bacteria and parasites from being introduced to the plant.

Cut the leaf off as close to the stem as possible. Try to only cut off yellow or browned leaves, leaving healthy green growth on the plant.

About the author 

Paul - Better Houseplants

Loves orchids and foliage houseplants. Always trying to be a better plant parent. Let's get growing!

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