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5 Reasons Why Plant Leaves Turn Yellow, and How to Fix Them

Have you ever noticed your once vibrant, green plant looking a little worse for wear, with leaves turning yellow? Fear not! Yellow leaves on plants, while concerning, are a common issue with easily identifiable causes and solutions. Read on to learn the reasons behind yellowing leaves and how to get your plant back to its healthy, green glory.


Common Culprits Behind Yellowing Leaves on Plants

The vibrant green color of most plants comes from chlorophyll, a pigment that plays a vital role in photosynthesis, the process by which plants convert sunlight into energy. When chlorophyll production is disrupted, leaves lose their green color and turn yellow, a condition known as chlorosis.


Several factors can hinder chlorophyll production, and diagnosing the cause is key to reviving your plant.


1. Overwatering and Underwatering

Water issues, either overwatering or underwatering, are the most common reason behind yellow leaves. 

Overwatering or underwatering is one of the most common issues behind yellow leaves on plants

When plants don't receive enough water, they prioritize keeping their core functions going, often at the expense of older or less essential parts. This means they might divert any remaining water to new growth or vital organs, leaving older leaves to dry out and turn yellow.


Meanwhile, excessive watering suffocates plant roots, hindering their ability to absorb water and nutrients. Moreover, when soil is constantly wet, it pushes out the air, essentially suffocating the roots. Suffocated and rotten roots can lead to yellowing leaves throughout the plant.


To know the condition of your soil, stick your finger a couple of inches into the potting soil. Underwatered soil feels dry, while overwatered soil feels soggy and may even have pooling water on the surface.


2. Nutrient Deficiencies

Plants need a balanced diet of nutrients for optimal health. The key culprit behind yellowing leaves in nutrient deficiencies is chlorophyll.


Chlorophyll is the pigment that gives plants their green color. It's also essential for photosynthesis, the process by which plants convert sunlight, water, and carbon dioxide into energy (sugar). When a plant lacks a crucial nutrient, chlorophyll production slows down or stops altogether. This breakdown of chlorophyll reveals the underlying yellow pigments naturally present in leaves, causing them to turn yellow.


3. Light Issues

Light plays a vital role in plant health, and both too much and too little light can cause leaves to turn yellow. Here's how light issues can disrupt chlorophyll and lead to yellowing.

Sunlight exposure is one of the most common issues behind yellow leaves on plants

In the case of too much sunlight, the intense light damages cells and disrupts chlorophyll production, causing leaves to turn yellow or brown, often with crispy edges. 


On the other hand, when light is scarce, plants can't perform photosynthesis efficiently. This reduces chlorophyll production, as the plant doesn't need as much to capture limited sunlight. With less chlorophyll, the green color fades, and yellow pigments become visible.


4. Temperature Stress

Plants thrive within a specific temperature range. When exposed to extreme temperatures, either hot or cold, it disrupts their normal functioning such as nutrient uptake, damages the cell membranes, and reduces chlorophyll production. 


In some cases, prolonged temperature stress can trigger a plant's natural leaf senescence process. This is when a plant redirects resources away from older leaves to protect new growth. As a result, older leaves turn yellow and eventually fall off.


5. Pests and Diseases

Pests like aphids, spider mites, or certain caterpillars feed by sucking sap from leaves. This disrupts the plant's internal processes and depletes it of nutrients, leading to yellowing leaves. Similarly, diseases caused by fungus, bacteria, or viruses can damage leaf tissue and hinder chlorophyll production, causing yellowing.


Diagnosing the Problem

First thing first, before you can take the correct action and turn your plant to its green color, you need to know the exact cause why your plant turns yellow. 


For this, observe your plant as the pattern of yellowing can offer valuable clues about the cause:

  • Uniform yellowing across all leaves. This could indicate overwatering, nutrient deficiency, or insufficient light.

  • Yellowing of older leaves first. This is a natural part of the plant's growth cycle. Older leaves lose chlorophyll as nutrients are redirected to new growth.

  • Yellowing starts from the lower leaves and moves up. This suggests underwatering or a nutrient deficiency, particularly nitrogen deficiency.

  • Yellowing between the veins while veins remain green. This is a classic sign of iron deficiency.


How to Fix Yellowing Leaves

After identifying the cause, it's time to look at several options for fixing your plants.


For water issues, if the soil is dry, water your plant thoroughly until water drains from the drainage holes. Allow the top inch of soil to dry before watering again. Meanwhile, stop watering immediately if the soil is too wet and allow the soil to dry completely. Consider repotting the plant in fresh, well-draining potting soil.


To tackle nutrient deficiencies, fertilize your plant with a balanced fertilizer according to the package instructions. 


Opt for a slow-release fertilizer to avoid overfertilization, which can also damage roots. For instance, use biochar charged with compost or fertilizer. Biochar will slowly release the nutrients into the soil and make them available for the plants for a long time.


Light issues are easier to handle. If your plant has insufficient light, move your plant to a brighter location and consider using grow lights if necessary. Provide shade or filter the sunlight reaching your plant if it is exposed to intense sunlight.


More or less similar to the previous issue, temperature issues can be solved by adjusting your plant’s environment. Relocate your plant to a location with a more suitable temperature range. Avoid placing plants near cold drafts or heat sources.


Finally, for pests and diseases, isolate the infected plant and treat it with insecticidal soap, neem oil, or other organic pest control methods for pest infestations. For fungal diseases, a fungicide may be necessary.


When to Say Goodbye: Severely Yellowed Plants

If a significant portion of your plant's leaves are yellow and dropping, and the stem feels mushy, it's best to remove the plant to prevent the spread of disease to other healthy plants. However, don't despair! You can propagate healthy parts of the plant, like stem cuttings, to create a new, vibrant version of your favorite greenery.


Conclusion

With a little knowledge and care, you can effectively diagnose and address the causes of yellowing leaves on your plants. From proper watering techniques to identifying nutrient deficiencies, this guide equips you with the tools to nurture your leafy companions and keep them vibrantly green. 






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