Why are my plant leaves turning yellow? Top reasons and solutions

Is your green friend suddenly getting yellow leaves? That could be a sign that something is wrong with your beloved plant. But don't worry too much! A leaf changing colour can happen for various reasons, and it's not always serious. In many cases, you can help the plant to get rid of the yellow leaf. To do this, of course, you first need to know what is wrong with your plant friend. We are happy to help you make the right diagnosis.

Why are my plants turning yellow?

It's chlorophyll that gives your houseplant's leaves their lovely green colour. However, chlorophyll is also responsible for photosynthesis, which is the most essential process in plants. When the plant is healthy and the photosynthesis process is running smoothly, the leaves stay green. Chlorophyll can't do its job correctly when something goes wrong (such as inadequate light, inadequate water, or a lack of essential nutrients). As a result, photosynthesis slows down, and the leaves turn yellow.

If you notice your houseplant's leaves turning yellow, it's the plant telling you that something needs to change in its environment or care routine.

Top 8 reasons why the leaves of your houseplants turn yellow

1. Overwatering or Underwatering

Too much or too little water is one of the main reasons behind yellow leaves. In soil that is too wet, roots cannot breathe properly. They suffocate, close themselves off and therefore can no longer transport water and nutrients that plants need.

Too little water or even drought has a similar effect. With too little water, plants cannot absorb the essential nutrients they need, resulting in yellow leaves.

How to fix it?

Examine how much and how often you're watering plants. If the soil is too soggy, you might be overwatering. If it's bone dry, you might not be watering enough. Remember, the watering needs of plants can vary significantly based on the type of plant, its size, the pot it's in, and the environment it's in.

2. Poor Drainage

When a plant's potting environment has poor drainage, excess water cannot escape from the soil. Instead, it accumulates and saturates the soil, leaving it constantly wet. As a result, the root system gets damaged, the transport of water and nutrients is hindered, and leaves can't get the essentials for life, disrupting photosynthesis. Therefore, the leaves start breaking down chlorophyll, and what remains is a yellow leaf.

How to fix it?

Use pots with drainage holes, make sure your soil is airy and well-draining, not damp and hard and make sure your watering routine is proper. If you are using sauces, don’t forget to empty them regularly. If your pot doesn't have drainage holes, consider repotting to one that does.

3. Too much sun or too little light

If a plant isn't getting enough light, its leaves may turn yellow. This happens especially if you place them away from a window, such as in the hallway, no-widow bathroom or in a dark corner. On the other hand, excessive direct sunlight can cause a plant to become sunburnt, which can also result in yellow leaves.

How to fix it?

Before you start diagnosing it, look up your specific houseplant light requirements. Then it’s time to look at the spot where it is located. Is it in direct sunlight when it prefers indirect light? Or is it in a shady spot when it needs plenty of light? Adjust the location of your plant based on its specific light requirements. For certain species, grow lights can also be an option.

4. Nutrient deficiencies

Common nutrition problems are under- or over-fertilisation. So it's important to pay close attention to how much fertiliser you can use. Often plant enthusiasts tend to give a little more so their plant can grow nicely. Unfortunately, in this way, you create a toxic environment which 'burns' the roots of your plant. As a result of both causes, nutrient transport is disrupted, and leaves eventually turn yellow.

How to fix it?

Let's take a moment and try to remember when you last fed your houseplant with fertiliser. Now, check the care guide for your plant and see what it suggests about how often you should be fertilising it. Are you doing it more often or less frequently than recommended? Based on what you find, you may need to adjust how you're feeding your plant.

5. Temperature stress

Temperature also contributes to the colour of the leaves. When it is too hot or too cold, leaves can change colour. Tropical plants are not used to the cold and also do not cope well with low temperatures or drafts. This, in turn, will cause leaves to turn yellow. Is your plant exposed to warm or cold temperatures for a longer period of time? Then the leaves will eventually turn brown.

How to fix it?

Loop up what are your specific houseplant temperature requirements. Usually, they have their optimal range and minimum they can handle. Most of plants don’t like cold drafts or too much heat, so keep your precious houseplant away from open windows/doors and heating vents.

6. Pests

Common pests such as spider mites, aphids, thrips or mealybugs can cause yellow leaves. The sap-sucking insects puncture holes in the leaves, causing them to become yellow or deformed. Most pests leave clear signs on the leaves, making it easy to recognise an infestation.

How to fix it?

So check your houseplants regularly for pests, and do not forget the underside of the leaves, the stems and the potting soil. Have you spotted a pest? Place the plant in quarantine and read all about the pest on our PLNTSdoctor page!

7. Natural ageing

Luckily, a yellow leaf does not always mean that something serious is going on. Just like us, plants age too. As they mature, it's completely normal for the older, less efficient leaves to turn yellow and fall off. This is a part of the plant's way of redirecting its resources and energy towards new, more effective growth. Does a leaf occasionally turn yellow on the lower part of your plant? Then your plant probably just wants to get rid of its old leaves in order to make new beautiful leaves again!

How to fix it?

unfortunately, ageing is something we can't stop! The best thing you can do if your plant is suffering from yellow leaves is to cut them off so your plant can focus all of its attention on growing new, green leaves!

8. Winter dormancy

Many houseplants go into dormancy during the winter months. This is a natural response to shorter and darker days or cooler temperatures. It's a rest period that allows plants to survive less-than-ideal growing conditions and store energy for the next growing season.

While it's a natural part of a plant's life cycle, dormancy can often lead to your plant's leaves turning yellow. Don't worry, it's probably nothing serious! As your plant slows down its growth, it might let go of older leaves, causing them to turn yellow and fall off. During dormancy, your houseplant simply doesn't need all of its leaves.

How to fix it?

If you notice your indoor plants developing yellow leaves during winter, don't panic right away. First, check if the plant is of a species that typically goes dormant in winter. If it is, and if the plant seems otherwise healthy, it may just be in its rest period. You'll likely see lots of new leaves on your sweet houseplant in the spring!