Houseplants are one of the most relaxing hobbies there is, if you ask me! However, there’s noting LESS relaxing than dealing with plant leaves that are turning yellow for no apparent reason. While yellowing leaves are commonly caused by too much or too little of either sunlight or water, it can be difficult to tell what exactly the culprit is. Fortunately, use this guide (with photos!) to determine what exactly is causing plant leaves to turn yellow and how to stop the problem.
Common Causes for Yellowing Plant Leaves
Too Much Water/Root Rot
One of the most common causes of plant leaves that are turning yellow is a fungal disease caused by overwatering. Plants that are overwatered are unable to drain the excess water from their soil, which creates an environment ripe for a root rot fungal infection. Plants that are overwatered/struggling with root rot are usually soft, soggy, and have soft brown spots along the edges. If you suspect your plant has been over watered, you can either treat the root rot issue with hydrogen peroxide, or simply allow the plant to dry out and bounce back. It’s up to you and the severity of the issue.
The photo above is a Phioldendron White Knight in the beginning stages of overwatering/a root rot infection. Because the yellowing is mild, I chose to move the plant to a sunnier window in hopes that it would easily dry out.
Too Little Water
Plants whose yellowing leaves are the cause of too little water will have edges that curl inward. Additionally, plants who are in the early stages of dehydration will appear extremely limp and fragile. Give the plant a deep watering to get things bag to normal. Additionally, cut off any yellowing that has already appeared. Not only will this help you keep hold of the issue (its easier to tell if the problem has gotten worse or not) but yellow leaves often can’t be revived, so this is better for the whole of your plant.
The above photo is a Tinike Rubber Tree who has been underwatered. I elected to cut off the affected leaf and give the plant a hearty drink.
Fertilizer Burn
Fertilizer Burn occurs when you have applied too much fertilizer to the soil of your plant. Essentially, the soil gets bogged down with minerals and can’t flush them out. This results in the minerals emitting via the plant leaves. Fertilizer burn on plants look like yellow spots, streaks, or actual burn marks. To treat, give your plant a hearty drink of water and flush out the minerals. Let the water drip from the drainage holes for several minutes.
The Pothos N Joy photographed has been fertilizer burned. Fertilizer burn commonly looks like a dramatically yellow leaf in a sea of green, with no other watering/sunlight issues.
Too Much Sunlight
Sunburn is another common cause of yellowing plant leaves. Sunburned leaves will appear yellow or white, and sometimes, if the burn is severe enough, will blister or turn completely brown. To treat the issue, cut off affected plants and move the plant away from direct sunlight.
Pinstripe Calatheas (pictured above) are the most susceptible to yellowing plant leaves. The cause of the yellowing above happened after I left it in the sun all day.
Plant Pests
Plant pests like powdery mildew, aphids, and spidermites are often the cause of yellowing plant leaves. However, the course of treatment is often different based on the plant at fault for the investation. To treat a plant whose yellowing leaves are caused by pests, follow this guide.
The signs of powdery mildew on a begonia maculata.
