Bonsai Yellowing (What to Do and Why It Happens)

  • By: Josh Koop
  • Date: March 3, 2022
  • Time to read: 6 min.
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A bonsai, despite its tiny stature, is still a tree. It also has to deal with all of the issues that regular trees do. Like trees, bonsai trees can also turn yellow for various reasons, which is a matter of concern for bonsai lovers. Now, what to do when bonsai leaves turn yellow

Bonsai leaves can turn yellow because of a lack of care and nutrition. With proper care, you can revive the leaves. Usually, providing sufficient water and sunlight is enough to revive a bonsai. But in extreme cases, you have to add nutrients to the soil.  

In this article, I will tell you how to care for bonsai tree leaves that turn yellow. Before that, we must discuss why the leaves turn yellow so that you can avoid the problem in the future. 

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Why Do Bonsai Tree Leaves Turn Yellow?

Some bonsai trees turn yellow for natural reasons. However, the yellowing of a bonsai at the wrong time of the year is a matter of concern for bonsai growers.

Here are some reasons your bonsai tree’s leaves are turning yellow: 

Natural Time Of Yellowing

You have been taking good care of your bonsai, but suddenly, you find your bonsai leaves yellowing and falling off. Before you panic, determine your bonsai type and season of the year. 

If your bonsai is a deciduous tree such as maple or elm, it will naturally turn yellow in the fall. The leaves look yellowish, and eventually, they will dry. Many evergreen bonsai do not shed all their leaves. But their leaves can still turn yellow. Then the older leaves will fall off in the fall. 

But the bonsai will become green again in spring. So, there is no reason to worry as it is a natural process for these bonsais. 

Under Watering Or Overwatering

Like regular trees and plants, bonsai also require proper watering regularly. Underwatering or over-watering, the bonsai can cause the yellow color of the leaves. 

Bonsai gets the minerals and nutrients from the soil through the water. So, it is crucial to water your bonsai regularly. When you skip watering a bonsai, the leaves eventually turn yellow and die. Underwatering will stop the natural growing process of the bonsai. 

Over-watering can also be a cause of the yellowish color of the bonsai. The bonsai cannot process too much water, and the roots start to die. Hence, the leaves become yellowish. 

Choosing the wrong pot causes severe damage as well. If there is no drainage hole or the holes are blocked, the extra water cannot pass through and stay in the soil. 

Lack Of Sunlight

Sunlight is extremely important for both indoor and outdoor bonsai trees. Trees need chlorophyll in their leaves to keep the leaves green. Without sunlight, bonsai cannot produce chlorophyll. Experts say a bonsai needs 4–5 hours of direct or indirect sunlight. 

So, check if your bonsai is getting enough sunlight or not. Keeping it under shade for a long time hampers the process of chlorophyll production. Consequently, the leaves look yellow. 

Environmental Stress

Growing bonsai in the wrong environment causes stress and can lead to yellowing of the leaves. You may be keeping an outdoor bonsai indoors. The lighting conditions and temperature may not be suitable for it. 

Bonsai trees can also be stressed when you re-pot them and the pot size is not suitable. Due to extreme stress, bonsai leaves lose their natural green color. 

Lack Of Minerals And Nutrients 

Bonsai trees are grown in small pots. The health of the bonsai greatly depends on the soil quality. Lack of nutrients and minerals in the soil is another reason your bonsai tree leaves are turning yellow.  

The quality of the soil may have deteriorated, and it may not have the necessary minerals to keep the bonsai green. Hence, you need to re-pot a bonsai or add minerals to the soil. 

Hard Trimming And Wiring 

Rough handling of bonsai trees also stresses them. You may find your bonsai leaves yellowing after you have trimmed them. You might have over-trimmed the bonsai, causing it to turn yellow because of stress. 

The same goes for wiring. You need to wire your bonsai to control the growth. Hardwearing can break the delicate branches and get infected, which causes the yellowing of the leaves.

Moreover, removing the wires before the same season weakens and discolors bonsai. 

What To Do When Bonsai Leaves Turn Yellow?

If your bonsai leaves have already yellowed, you are probably wondering if it is possible to return them to their original color. It actually depends on the damage. But most of the time, it is possible to solve the yellowing problem. 

Here is what you need to do if your bonsai leaves turn yellow. These steps are also necessary to prevent bonsai from getting yellow leaves in the future. 

Provide Sufficient Light

Sunlight and water are the most essential elements for your bonsai’s health. Check if your bonsai is getting enough sunlight. Even indoor bonsai trees need sunlight. Leave your outdoor bonsai outside so that they have enough sunlight. 

You can keep the indoor bonsai near the window for indirect sunlight or install grow lights for it inside. However, do not move your bonsai too much. Moving them from indoors to outdoors constantly may cause stress. 

Water Adequately

When you find your bonsai with untimely yellow leaves, check the soil. See if the soil is too wet or dry. You can put a stick into the soil close to the roots. If the stick is moist, it means your bonsai does not need to be watered. If it is too dry, water it adequately. 

You should not ignore watering your bonsai regularly. However, refrain from overwatering. Over-watering will not help the yellow leaves become green. It may even get worse.

So, water your bonsai regularly like you should have done. With time, the leaves will go back to their natural state. 

Check The Bonsai Pot

Water blocking inside the pot is a serious problem for bonsai. You must plant and grow your bonsai in a pot with drainage holes. When you water the bonsai, the excess water should come out through the hole in the bottom of the pot.

Besides, the pot should be the right size and shape for your bonsai. It must be able to hold sufficient soil for your bonsai. There should be enough soil to support the bonsai not only for grounding but also for minerals and nutrients.

If you think the pot does not have the right size or depth for the root system of the bonsai, change the pot. 

Add Nutrients And Minerals

Your bonsai leaves may not return to their natural color even after you try the above methods. It means the problem is in the soil. It does not have the necessary nutrients to keep the bonsai happy. So, you have to add some fertilizer. 

To cure the yellow leaves of the bonsai, you need to mix nitrogen, phosphorus, and potassium. Do not overuse fertilizers as they negatively affect your bonsai. Start by mixing a small amount of fertilizer and waiting for its effect on the leaves. 

Trim And Wire Your Bonsai Carefully

If you are just starting to grow bonsai plants, you may make some mistakes. Over time, you will learn a lot. To prevent yellowing of the bonsai trees, first, learn how to trim and wire the plant without stressing it. 

Trim and wire your bonsai at the right time of year. Unnecessary trimming and tight wiring should be avoided. Do not prune or trim the bonsai if the leaves are already yellow. Let the bonsai heal first, and then you can trim it.  

Conclusion 

So, what to do when bonsai leaves turn yellow? As you can see, you can take steps to solve the problem and prevent it from happening to bonsai. However, turning yellow leaves back to their natural color is not possible overnight. 

You need to be patient and take regular care of your bonsai to return it to its former glory. 

Check Out Bonsai Boy for the BEST High-Quality Trees

Bonsai Boy helps you find the best bonsai trees. You’re going to LOVE these trees because they grow fast and look great in your home or office.