Bonsai leaves turning yellow is the most common occurrence when managing your plant. However, many people still react too quickly and carelessly to this issue, and they end up doing further harm instead of helping their small tree!
Close inspection and understanding of what is going on with your bonsai tree are fundamental and can help you establish whether your miniature tree is suffering from a lack of nutrients, poor watering practice, stress, or other common factors!
We’re here to help you out and better understand what ails your bonsai trees and how to help them go green again.
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What Can Cause Bonsai Leaves To Turn Yellow?
Several factors can cause bonsai leaves to turn yellow. If kept outdoors, it can be a natural occurrence as winter approaches. Poor watering practices and a lack of minerals can also affect its leaves. Bad pruning or wiring are also common culprits, and so are other stress factors.
Bonsai implies growing tiny trees in pots, and the very name comes from the Japanese potted tree! You could grow many types of bonsai trees in your home. It can be a tree you collected in the wild (i.e. Yamadori) or a tree you’ve bought as a bonsai in a nursery or your local garden center.
Your tree is either a deciduous tree or an evergreen, an indoor or an outdoor bonsai. No matter how you’ve supplied your tree, all of the bonsai foliage may and will, at some point, go yellow.
If you’ve acquired your bonsai tree from a nursery, it’s probably an indoor type of bonsai and is a deciduous tree. These trees can either be Sageretia, Japanese Maple, Jade tree, Korean hornbeam, or any other type of deciduous tree!
The yellowing of the foliage is and can be caused by several things! It can be either a perfectly natural occurrence, a sign of disease or mismanagement, or any of these combined.
Nevertheless, with bonsai, yellow leaves mean a warning! What will help you help your tree in the end is understanding and recognizing what’s the matter with it. So let’s get started!
– Perfectly Natural Occurrence
Take a look at your surroundings – has autumn already started in your place? If so, then nature is the likely cause of your leaves going yellow. What happens is that your bonsai tree is preparing for winter dormancy and is about to shed the leaves, so it’s lowering the flow of sugars and starches.
Instead of sending nutrients to the leaves, it’s storing the energy in the root to survive the winter and days without the sun. The growing phase suddenly slows down, and the leaves go yellow as a result!
This will last for anywhere between two weeks to more than a month when your bonsai will have shed their entire foliage and go to winter sleep. If your bonsai is an indoor tree, then the warmth of your room can fool it into not shedding all of the leaves.
– Poor Watering Regime
Bonsai trees need all our help when it comes to keeping them alive. They are committed to just a small handful of soil, which always has to be tended to. We are the keepers of a fine balance, and this is ever so apparent in our watering regime.
If you give your bonsai tree too much water, it won’t function as properly. Overwatering is what will ultimately kick off root rot disease and yellow leaves. However, beginners always seem to make the mistake of caring too much! Overwatering can be caused by many factors, and all of these factors add to water accumulation near the roots.
Your soil should always feel and look like a wrung-out cloth instead of being completely wet. All living things need air to live, and the same goes for your bonsai!
On the other extreme, we have underwatering to blame for the yellow leaves. Underwatering dries up the soil to the point where your roots begin to die, and the bonsai tree leaves turn yellow and curl up! Whenever you see bonsai leaves curling up or going yellow without any particular reason, you should assume that your bonsai tree needs a drink.
Many people make the mistake of only misting their bonsai, thinking this will be enough, but it won’t! If only your leaves receive water, this won’t be enough, and they will soon be turning yellow.
You can quickly check the soil by looking at and feeling it. If the top soil layer has gone dry and the first few inches of soil don’t feel moist to you, underwatering is your most probable problem.
– Pruning or Wiring
Ah yes, the very reason why we all begin to keep bonsai is to keep that beautiful canopy and silhouette clean and beautiful. The truth is, your bonsai needs to have periods when it goes wild and grows unchecked. And, of course, there are periods when it needs to be trimmed.
What many rookies are doing wrong here is that they trim their bonsai far too often! Any pruning or hard trimming of the canopy and leaves weaken your tree and are very stressful for it. If you trim your tree too often without giving it a timeout to rest and regrow strength, it will inevitably get yellow foliage and even die!
Another big issue comes with wiring. Place structural wires only when it makes sense. Or rather, where it makes sense, or better yet — both!
Wires can be kept on branches for a finite amount of time — leave them on for too long and they will bite into the bark and damage the sap flow. This in turn will weaken the tree and cause the leaves to turn yellow!
– Poor Mineral Balance
Fertilization is a crucial practice in the art of bonsai trees growing. First of all, fertilization should be scheduled appropriately, as the growing season will demand more nutrients than the dormant season.
The other reason why fertilization shouldn’t be taken naively is that we can have too much of a good thing, and having too much of any mineral in the soil can harm the roots, hurt the tree and cause leaves to turn yellow in the end!
You can always check the levels of minerals with a soil testing kit, but we advise you to keep a good fertilization regime, and all will be well!
– Other Stressful Scenarios
There are other stressful situations you can expose your bonsai to, and these won’t be appreciated. All of them can cause your leaves to go yellow and even fall. Bonsais are like kings of the tree world, and they demand perfect conditions, all varying from species to species.
Some will like to be kept as indoor bonsai, taking only outside turns in the summer. Others will only be outside specimens! You can weaken them when you repot them too.
What Can You Do if Your Bonsai Leaves Are Turning Yellow?
If your bonsai leaves are turning yellow, you can either prepare the tree for winter, if you’re keeping it outdoors, and if it’s indoors, you’ll need to learn how to water it properly.
You’ll also need to learn correct pruning and wiring techniques, add adequate fertilizer, and eliminate stress factors.
– Preparing the Tree for Winter
You can aid your bonsai tree and help it transition to winter dormancy by defoliating the tree as soon as it shows the signs of fall yellowing or browning of the leaves. Simply take a defoliating tool and remove each leaf by pinching it off the tree – this way, you’ll tell your bonsai that now’s the time to go to sleep.
Remember, this process will only happen to deciduous bonsai, while evergreen trees should stay green all year round.
– Establishing a Good Watering Regime
Almost everything related to the health of your bonsai will be in the water and how much or little you’re giving.
If your tree appears thirsty, give it a thorough watering! Place the bonsai under a 15-second stream of water and let it enjoy every second of it. Turn off the water and let the soil have its drink, and let the extra water go through the pot and out the drainage holes. After this, repeat with another 10 to 15-second shower and return your bonsai to its pebble tray.
Another way of hydrating is drowning the entire pot in a tub of water for around a minute or so. After this, take the pot out of the water and let the water pass through the soil and the bonsai pot, and then repeat the entire process once again!
A good watering regime doesn’t rely on any given number of days the bonsai should be watered. Instead, rely on touch and sight. If the soil appears dry and the first few inches of topsoil have lost moisture, it’s time for a bath. Generally, this will depend on the growing season too – in summer, it can be every day, while in winter, every other week!
– Trimming And Wiring Done Right
Only trim your trees when they are green, healthy, and wildly alive! You’ll know this by their luscious foliage and energetic growth.
As a general rule of thumb, trim and wire your trees structurally only in late winter and early spring, just before they go into that energy-positive state. You can trim once more in early summer, but only if the growth has been evident.
Never prune trees that look weak or if the leaves appear yellow. Also, pruning your trees in high spring and high summer may be bad — think of it as sending a negative vibe to the tree when it’s in a positive mindset!
Don’t leave a wire on the tree for more than a few months at any given time. Wires are placed for two reasons — directing a branch and preparing a tree for a show. Every branch should be corrected with a wire within two months. You can always place a wire next year if you’re not satisfied with the effects of the previous wiring!
– Fertilizing the Bonsai Properly
Improper fertilization is a hard-to-revert thing without having to repot your bonsai, and you can technically do that on only two to three occasions per year. So, it’s for the best to keep your fertilization on point and, like all things bonsai – in a fine balance!
You should use a well-balanced bonsai fertilizer, and your tree will do just fine with this. The fertilizer will be either liquid or solid, and both versions are fine as long as you can keep a good schedule.
Now, when we talk about schedules, this is where most folks get it wrong! You should follow the feeding schedule and the amounts as specified on the package (each retailer’s advice may vary).
But not every season will require the same schedule or even amount of fertilizer! That’s why you should start fertilizing as the first buds pop open (early spring), and you can fertilize into summer.
The fall period is a slow period, but you can continue fertilizing and gradually skip over every other fertilization by winter time when all your fertilization should stop for the growing cycle.
– Treating Your Bonsai Right
Stressful situations can cause leaves to go yellow, and when it comes to bonsai, almost everything out of the ordinary is considered a stressful situation. Don’t repot your bonsai too often, and only look to do so when the tree has become root-bound (roots have outgrown the pot)!
You can repot your trees only at specific times of the year (early spring, early summer, late summer). Also, whenever you are changing the place for your bonsai, be careful not to do it at times when the temperature difference will be too high, or they may react badly!
Conclusion
Bonsai leaves turning yellow is a serious thing. Bonsai care includes special attention at all times, and if anything goes slightly sideways, they will react yellow, but the situation can be dealt with.
Let’s remind ourselves of the key points:
- Close-up inspection is crucial when you notice yellow bonsai, as not every cause will require drastic measures!
- Overwatering and underwatering can both be handled with relative ease, while nutrient deficiency and repotting may require a more drastic approach.
- The same will go for hard pruning and wiring, and you should know when to do it and when it’s best to leave the plant alone to recover!
- Whichever you’re dealing with, remember that with bonsai trees, less meddling will often do more than trying to constantly do something to make things better.
- Stick to the feeding and watering regime that relies on studying and watching your plant, and you should be ok.
Now that you know how to handle the yellowing of the leaves, we’re sure that your bonsai specimens will grow happy and well!
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