Why Your Houseplant Leaves are Turning Yellow & How to Treat
Houseplant leaves turning yellow and don’t know what to do? Yellowing leaves have many causes including too much water, too few nutrients, pests, or just natural process. It can be shocking and disappointing to see yellow leaves, but don’t panic— it’s usually fixable and quite normal to experience. We’ll outline exactly what could be happening depending upon a few factors like time of year, age of plant, and care routine.
Many indoor plant-tenders believe that when leaves yellow that something is wrong or that they’re not caring for the plant properly. But that’s not always the case! One of the best rules to remember when taking care of plants, is that constant perfection is unattainable. Plants are living things and therefore will experience different phases throughout their life. In fact, it’s completely normal for many plants to phase out certain leaves.
Is your plant seemingly healthy (besides the yellow leaf)?
You'll first want to rule out normalcy before beginning to diagnose and treat a healthy plant. As new growth emerges on a plant, more energy is needed to supply the larger plant with vitality. And as a result, plants will shed leaves that are usually smaller and located lower down (closer to the soil). So if your plant falls into the category of otherwise healthy, this could be the reason a plant’s leaf is yellowing. It’s normal, and actually healthy for the plant. This process means that the plant is vitally active and making room for new growth. Simply wait for the plant to drop the leaf and then make sure to dispose of it to prevent any bugs that may be attracted to the decaying matter.
Also, all houseplants need to be repotted (depending on the type of plant) every 1-2 years. Going up a size to support the new growth of a plant is imperative for sustained health. If you notice yellowing leaves and you haven’t repotted in a while, or if you notice roots starting to creep out of the bottom holes of the pot, then it’s time to give the plant a bigger home. When roots become bound within their container, plant growth may slow and leaves may yellow and die. To fix this, simply repot the plant into a pot about 2-3 inches larger (deep and wide). Then water thoroughly to allow all of the roots access to moisture.
Healthy plants will also experience seasonal shifts as the weather outside changes. During the spring and summer months, you will likely notice faster growth and the plant will require more water. On the other hand, the cooler months tend to launch houseplants into a semi-dormant stage. With slowed growth and the need to adapt, you may even notice that some plant leaves start to yellow and eventually drop leaves. This natural process is the plant’s way of dealing with changes and surviving through. To best support your houseplant during the winter shift, simply allow the plant to rest and don’t try to “fix” any problem that doesn’t exist. It’s also helpful to monitor your plant during winter since it is more vulnerable— lookout for pests weekly and treat immediately if a problem arises.
In addition, another indoor environment issue could be cold drafty areas the plant is exposed to. The placement of the plant inside is important to health and longevity. Make sure that the houseplant is not in a direct path of a vent or a drafty window. These subtle adjustments can greatly affect the plant’s health.
In cases where yellowing leaves are caused by plant owners, it’s most of the time caused by overwatering. If you’re seeing more than one leaf that’s yellowing, water could very well be the cause. Go ahead and check the soil of the yellowing plant, and depending on the type of plant and how much moisture is required for that type of plant, you can get a feel for whether your watering routine is an issue. Generally speaking, if the top of the soil is wet (and you haven’t just watered), there’s too much moisture. Overwatering is the number 1 culprit of declining plant health and death. That’s why it’s imperative that you never water too much and when in doubt, underwater. Plants can recover better from too little water but cannot always bounce back after too much.
Also, the watering issue may be partly caused by other preexisting issues like soil or pot choice. If your soil isn’t allowing for thorough drainage, water could be accumulating for prolonged periods. This does not bode well for the plant’s root system and overall health. Always make sure that you have a well-draining potting mix for your indoor plants. And of course, pots need to have drainage for every indoor plant that you have. Without drain holes, you cannot control how much water is sitting at the bottom of the pot and saturating the soil and roots. This can lead to bacteria growth, root rot, and eventual plant death.
Another reason for yellowing leaves could be due to insufficient nutrients. If yellowing is occurring alongside other issues like stunted growth, discoloration of foliage, or leaf blotchiness, then it very well could be a nutrient problem. The first step to correcting this type of issue is to make sure your plant is getting enough fertilizer. All plants are different in their needs of certain nutrients like nitrogen, potassium, magnesium, and iron. But typically for tropical indoor plants, it’s recommended to fertilize with a general houseplant fertilizer once a month during the growing seasons (typically spring and summer). And make sure that you don’t over-fertilize, as that can lead to other problems such as leaf burn.
One last recommendation here is to occasionally water your plants so thoroughly that the water drains out the bottom holes, a process called leaching. When you water utilizing this method, you're essentially flushing the soil of any buildup. Sometimes salts can accumulate within the soil and harm the roots and plant (and cause yellow leaves). Allowing the water to trickle through for a couple of minutes can help support the health of the soil and in turn, the plant.
As mentioned, it’s important to regularly check for pests by scanning the top, underside, and nooks of the foliage. We recommend weekly check-ins so that if you do spot an issue, you can remedy it quickly. Pests become a much larger problem when found too late as they can cause irreversible damage, become more difficult to eradicate, and can spread to other house plants quickly. So monitoring and getting any potential issues under control as soon as possible is really the best control method.
However, if you suspect pests and notice leaves are getting lighter in color or vibrancy (sometimes visually yellow), it could be spider mites. Spider mites feed on plant cells and spin a fine web on the surface of plant leaves. Looking closely, you may see the tiny, reddish pests slowly moving around. If this is the cause of your yellowing foliage, find an insecticidal spray and drench the plant before wiping away. If the case is so severe that yellowing has occurred, you’ll likely need to repeat the process over the course of a couple of weeks to ensure the pests are wiped out and there are no stragglers. Luckily, spider mites can be manageable and though the existing yellow leaves are irreversible, new growth will emerge normally!
While there are many different conditions that can cause leaf yellowing, most are not a cause for great concern. So don’t fret, plant parents, it’s likely recoverable! As living things, plants are going to experience highs and lows, including yellowing leaves, throughout their lifecycle. The key as a plant owner is to accept and adapt. While this list is not exhaustive, you now have fundamental tools to identify, diagnose, and even treat common yellowing issues that arise. As a parting reminder, while it’s important to inspect the plant regularly, if you’ve found nothing wrong, refrain from making drastic changes or fixes that could further stress the plant.