Among several reasons for bonsai to turn yellow, one is the seasonal fall, and the other is access to nutrients or nutritional deficiency.
In addition, improper care could be among many reasons, for example, wrong soil proportion, Improper pruning, overwatering, underwatering, improper sunlight, and irregular repotting or fertilizer feeding, as bonsai are sensitive plants and need intense care until fully matured.
What Does It Mean When Your Bonsai Leaves Turn Yellow?
A bonsai tree can turn yellow for many reasons. It’s not a matter of concern if the seasonal fall of your bonsai is nearby. Like all other trees, Bonsai’s leaves will fall in autumn and leaves will turn yellow in autumn.
If it’s not autumn, you should worry then. Yellow leaves are a sign of excess watering or improper watering or improper care. One of the common problems that one can do is not taking care of the sunlight and nutritional needs of your bonsai plant.
For the same, we are going to discuss the major reasons for the yellowing of bonsai leaves and probable cures or measures to keep your plant healthy.
How Often Should I fertilize My Bonsai To Keep It From Turning Yellow?

The fertilization solution starts with choosing the right fertilizer. NPK are three main minerals that are needed by a tree. N stands for Nitrogen, P for Phosphorus, and K for Potassium. Besides that, calcium, magnesium, and sulfur are other minerals a bonsai will need.
Some Reasons For Your Bonsai If Your Bonsai Turn Yellow. Let us see some alarming reasons for your bonsai turning its leaves yellow.
● Overwatering
Overwatering is one of the key mistakes a new bonsai lover can make. Bonsai needs soil to be watered, and no stagnant water is needed. Also, excess water is a port for microorganisms and harmful pests. Steady water around the roots is also deadly to plants as it might start rotting the plants.
● Underwatering
One of the common mistakes with nurturing bonsai is underwatering. As bonsai is sensitive to stagnant water, we often underwater the plant and the leaves show negative signs of growth. Yellowing leaves and shriveled plants are among the signs that bonsai show when it is not watered sufficiently.
● Insufficient Lighting
Same as water, sunlight or artificial lights should be in moderation. Sunlight is the main source for plants to produce their food and that is why they need enough light and proper exposure to sunlight. Though it depends on the species of bonsai, a few hours of direct sunlight is a must for any bonsai to show its utmost growth.
● Lack of minerals or nutrients
Your bonsai might turn yellow to show the nutritional deficiency. All plants need minerals to thrive and be the most healthy ones, the shortage of minerals might be one of the reasons that your bonsai is turning yellow.
To get a balanced mineral source, the best thing is to regularly add fertilizers to soil or have a proportion of organic soil a little higher for your bonsai. However, excess fertilizer could also harm your plant, so you should always prefer professionals’ suggestions or knowledgeable individuals for the number of fertilizers to be used.
● Shape and size of Pot
Bonsai itself means tray Planting and the tray or pot is one of the key matters for the growth or deterioration of the plant. Enough space for roots is a must for the growth of bonsai. Every time when you are repotting your bonsai, the pot size should be larger
than the previous one. Also in terms of draining water, your pot should have sufficient holes to let the water run out while watering. So if your bonsai seems to be turning yellow, wonder if the pot you are using is fine enough or not.
How Do I Trim My Bonsai To Prevent Yellow Leaves?

Trimming, pruning, and repotting bonsai are stress-creating scenarios for the miniatures; one should be very careful when looking to trim or repotting bonsai. Now, these stresses might adversely affect the health of bonsai and can make leaves turn yellow. To avoid so, we have some tips for trimming and repotting for you.
● The season for trimming
An indoor bonsai can be trimmed year round but not when the temperature is at extremes on either side. An outdoor bonsai can be trimmed in the growing seasons i.e, March to September.
● Before trimming, take care of
Do not trim your bonsai when you have recently repotted the plant. It is necessary for a plant to settle in a new location (Pot) before you imply any adverse stresses to your bonsai.
A few species of bonsai, like pine and confiners, are sensitive to cutting and need pinching. Pinching all together is very sensitive and make sure your hands are clean and hygienic to plant in order to avoid giving away plant disease.
● Process for Trimming
The process of trimming bonsai trees starts with placing them in a free environment under direct light for proper inspection and visibility. Also, you should reach to bonsai in a manner that the plant is at your eye level.
Decide which branches are the ones you need to cut, and the cut should be in a manner that allows the branch to grow in the desired direction.
Using the right tools like a cutter or twig shears is the essential thing to consider. Regular trimming is fine when you see a section or branches of a plant have been outgrown. Also, make sure that the trimming is done when the tree looks healthier and not yellow. If your tree looks yellow or the soil is parched, avoid trimming your miniature.
● After Trimming
There can be chances that while cutting the branches or removing leaves, you might hurt the plant, and scars can be seen in your bonsai. To let the plant heal better and quickly, seal the wounds by cut paste. Cut paste are available in all bonsai shops and is very effective for a plant to heal.
Once the trimming is done, it’s time for roots to be trimmed. Yes, an equal amount of roots should be trimmed once you have restructured the upper part of the miniatures.
When Should I Fertilise My Bonsai?

For fertilizing your bonsai, there are some rules that help your plant to get the maximum outcome and to thrive. The season for fertilizing bonsai trees is early spring to autumn. Regular fertilization is a must for bonsai. As fertilization is a matter subjective to species of bonsai, let us see the fertilizing process based on species of bonsai.
- Tropicals and Subtropical: Weekly fertilization in growing months is necessary for tropical and subtropical species of your bonsai. From fall to spring, these species of bonsai will need monthly fertilization.
- Deciduous bonsai: Unlike Tropical and Subtropical species, Deciduous bonsai will go dormant after growing seasons, so all fertilization is to be done during the growing season. Weekly fertilization in the growing season seems good for deciduous.
- Confiners: These species of bonsai will not go dormant and will keep using fertilizers all year round, so the frequency of fertilizing should be once a week in growing seasons, whereas it should be twice a month in non-growing seasons.
When Should I Not Fertilise Bonsai Tree?
Never fertilize a tree that’s under stress. A stressed tree is one that is sick, newly repotted, or in need of watering (always water your tree before feeding). If repotting, wait at least a month for your tree to re-establish before reintroducing fertilizer
Frequently Asked Questions
1. How do you revive a yellow bonsai tree?
Adding fertilizers, proper exposure to sunlight, and a moderate supply of water is what is going to help your yellow bonsai revive and thrive the way it should.
2. What does an overwatered bonsai tree look like?
Yellow leaves and shriveling of smaller branches are signs of overwatered bonsai. Also, if you do not see tree growth, overwatering could be a reason.
3. Why is my bonsai losing color?
Losing color is a sign of improper care or inadequate nutritional supply, for plants not being green means a deficiency of sunlight and energy. Proper exposure to sunlight and adequate watering are a must for bonsai to thrive.
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