Growing bonsai trees isn’t always easy, especially for beginners.
During your journey, you will likely encounter various issues with your plants.
A significant portion of these problems will show up as signs on the leaves.
Being able to identify these signs is crucial, whether you’re a beginner or an experienced grower.
This way, you can discover what’s going wrong and how to restore your bonsai’s health.
Keep reading to learn about what yellowing, dry, falling, or burnt leaves may indicate in your bonsai.
Bonsai with yellowing leaves
If the leaves of your bonsai are turning yellow, this can be an issue in your cultivation.
However, don’t be alarmed, as in some cases, this is normal.
To determine if your bonsai has a problem, check whether only a few or several leaves are turning yellow.
- If it’s just a few, there’s no need to worry, as this is normal.
- If multiple leaves are turning yellow at the same time, it’s a problem.
Below, you’ll find the main reasons that can cause the leaves of a bonsai to turn yellow.
Before we look at these problems, keep in mind that leaves that are already fully yellow usually won’t turn green again. The goal is to stop new leaves from turning yellow.
Mineral deficiency
In nature, trees receive nutrients from organic compounds of other trees or animals.
For example, they are “fertilized” by leaves that fall from other trees and also their own leaves.
When cultivating your bonsai, you need to provide nutrients to your plant.
These nutrients are supplied through fertilization.
If you don’t fertilize your bonsai correctly, it will lack nutrients, and its leaves may start to yellow.
This happens because nutrients such as nitrogen, magnesium, and iron are needed to produce chlorophyll.
And without chlorophyll, the leaves turn yellow.
To prevent this problem, use a balanced fertilizer regularly during the growing season.
Here’s a tip: look at which leaves are turning yellow first.
- Older leaves turning yellow first: usually a lack of nitrogen.
- New leaves turning yellow while the veins stay green: usually a lack of iron, often caused by a high soil pH.
If your bonsai is short on iron, a chelated iron product or ferrous sulfate, used as the label directs, usually solves the problem.
Lack of water
Lack of water is one of the most common problems in bonsai trees.
And it’s also one of the leading causes of their death.
Bonsai trees and other plants need water to survive; without water, they lack energy, and without energy, they die.
If this is your issue, you may notice that the leaves are wilted and dry.
To resolve this problem, simply water your bonsai correctly.
See more:
- Boxwood Bonsai (Buxus) – Step-by-Step Care Guide
- Lemon Bonsai – Discover How to Easily Cultivate Them
- Bamboo Bonsai – How to Care, Curiosities and Species
Stress
Stress is caused by significant changes in the way your bonsai lives.
For example, if it was in a place with bright light and you moved it to a location with less light, it will likely experience stress.
Some of the factors that cause stress in bonsai trees include:
- Change of location
- Repotting
- Drastic change in cultivation methods
If you’ve done something that might have stressed your bonsai, give it some time to return to normal.
Cold exposure
Some bonsai species don’t tolerate cold temperatures well.
If you expose them to low temperatures for an extended period, their leaves may turn yellow.
This problem typically occurs during autumn and winter.
It mainly affects tropical species, such as Ficus, and cold-sensitive fruit trees, such as the orange bonsai.
To prevent this, bring them indoors when nights drop to about 13°C (55°F).
This will ensure that the leaves stop turning yellow.
Outdoor temperate species, on the other hand, need a cool winter to rest, so don’t keep them in a warm room all year.
Bonsai with dry leaves
If you notice your bonsai’s leaves becoming dry, this can be a significant problem.
To assess the possibility of recovering your plant, do the following:
- Gently scratch a small spot on the trunk with your fingernail
- If the layer under the bark is green and moist, your chances are high
- If it’s brown and dry, your chances are low
The main reasons bonsai trees develop dry leaves are as follows:
Lack of watering
As previously mentioned, inadequate watering of your bonsai is a troublesome issue.
Beginner growers often think that watering bonsai is the same as watering other plants.
Unfortunately, they learn they’re mistaken in the worst way possible – by losing their plants.
Bonsai trees are grown in fast-draining soil in small pots.
Therefore, they usually need watering more often than other plants.
Check the soil every day and water when the top layer feels slightly dry.
In hot weather, this may mean watering every day, or even twice a day for small pots. In cooler months, it may be every few days.
Be patient; if your leaves are dry, it may take time for the situation to reverse.
Injured roots
Roots are responsible for absorbing water and nutrients for bonsai trees.
If they’re damaged in any way, your plant will encounter issues.
There are several problems that can harm your bonsai’s roots, but one of the primary culprits is excessive water.
Essentially, excess water causes the roots to drown and rot.
Without healthy roots, your bonsai can’t absorb water, and consequently, it becomes dry.
High temperature
This is a relatively rare case, but it can occur.
If you’re placing your bonsai in an area with very high temperatures, it can hinder your plant’s water absorption.
Without water, the leaves will dry out.
Bonsai with falling leaves
Before discussing the main problems that cause bonsai leaves to fall, there are two things you should know:
- Deciduous species naturally lose their leaves in autumn. This is normal.
- Evergreen and tropical species, usually grown indoors, shouldn’t lose many leaves at once.
The main problems that can cause bonsai leaves to fall are:
Inadequate lighting
Especially for indoor bonsai trees, ensure that they’re not receiving too little light.
Bonsai trees, for the most part, require ample light for proper growth.
Therefore, place your plant near windows so it receives plenty of light.
Furthermore, excessive light can also be an issue.
If your bonsai is receiving too much light, its leaves may burn and then fall.
Improper watering and stress
Both stress and excessive or insufficient watering can cause bonsai leaves to fall.
However, since we’ve already discussed water scarcity and stress, let’s focus on excess watering.
Basically, overwatering your bonsai can lead to weakened roots.
In some cases, these roots may rot, further weakening your bonsai.
Without energy, it will lose its leaves.
Pests or diseases
Several pests can cause leaf loss.
Some gradually consume the leaves, while others sap nutrients from bonsai trees, weakening them.
Additionally, your plant can also be attacked by diseases, and when weakened, it may lose its leaves.
To learn more, read the article Pests and Diseases in Bonsai Trees.
Excess or lack of fertilization
If you’ve checked each of the above factors and haven’t found the cause of your bonsai’s leaf loss, don’t panic.
Excessive or insufficient fertilization can also cause this issue.
Therefore, ensure that you’re fertilizing your bonsai properly.
Bonsai with burnt leaves
Burnt leaves are typically a result of excessive sun exposure.
If you notice your bonsai starting to develop burnt leaves, move it to a location with less sunlight.
Additionally, there are three other problems that can cause burnt leaves on bonsai trees:
- Root rot: This occurs when your plant’s roots remain wet for an extended period.
- Lack of water: Leaves burn because your bonsai can’t provide the same amount of water that leaf transpiration loses when exposed to the sun.
- Excess fertilizer: Fertilizer salts build up in the pot and burn the leaf tips and edges.
Conclusion: main problems in bonsai trees
These are the main problems you may encounter when cultivating your bonsai trees.
I hope this article has helped you identify and address them.
If you have any questions, feel free to leave a comment below.
Sources: University of Illinois Extension, Iowa State University Extension, New York Botanical Garden, Matthaei Botanical Gardens (University of Michigan), and Washington State University Extension.
Read more about bonsai:
- Mulberry Bonsai – How to Care in 7 Steps
- Pomegranate Bonsai – How to Care in 6 Simple Steps
- Jabuticaba Bonsai – Care to Have Fruits
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