Why Do Bonsai Trees Lose Their Leaves?

Indoor or Outdoor Bonsai?

This is probably the most important distinction to make.

Outdoor bonsai trees experience the seasons and behave much like their full-sized counterparts growing naturally in our gardens and countryside.

Indoor bonsai are generally species originating from warmer climates. They prefer the relatively warm, stable conditions that we can provide inside our homes and offices.

The reasons they lose their leaves can therefore be very different.

Why Do Outdoor Bonsai Trees Lose Their Leaves?

With an outdoor bonsai, we first need to know whether the species is deciduous or evergreen.

Why Do Indoor Bonsai Trees Lose Their Leaves?

Most indoor bonsai species originate from warmer climates and appreciate a warm, bright and relatively stable indoor environment.

Popular examples include Fukien Tea (Carmona microphylla), Sweet Plum (Sageretia theezans), Ficus species, Jade and Zanthoxylum.

We generally consider these evergreen bonsai, but that doesn’t mean they never lose a leaf.

Quite the opposite.

Leaves have a natural lifespan. As a bonsai produces fresh growth, some of its older leaves will eventually be discarded.

The tree’s strongest growth activity is concentrated around its actively growing tips. It is therefore quite normal to see the occasional older leaf further back turn yellow and fall while the ends of the branches remain healthy and continue producing fresh foliage.

If the bonsai is otherwise vigorous and you can see healthy new growth, the loss of a few older leaves is rarely something I would worry about.

Think about any healthy houseplant you have owned. You wouldn’t necessarily panic because one older leaf turned yellow. Bonsai trees are no different.

My Bonsai Has Just Arrived and Is Losing Leaves

There is another situation we see quite regularly: a bonsai starts dropping a few leaves shortly after moving to its new home.

Again, this does not automatically mean there is a problem.

Imagine the change from the tree’s point of view.

At our nursery it has become accustomed to a particular temperature, humidity and level of light. It is then carefully packed, transported and placed into a completely different environment.

Even moving a bonsai from one room to another can alter the amount and direction of light it receives.

Some indoor bonsai respond to this change by shedding a proportion of their older foliage while they acclimatise to their new surroundings.

We generally see this within the first three to four weeks.

What I look at is the overall condition of the bonsai tree. If the growing tips remain healthy and fresh growth continues to appear, a little older leaf loss during acclimatisation would not concern me.

Give your bonsai time to settle. Try not to react to every falling leaf by continually moving it, changing its watering routine or giving it lots of different treatments. A stable environment is usually far more helpful.

When Should I Worry About My Bonsai Losing Leaves?

This is where experience becomes useful, because there is a big difference between a bonsai naturally shedding a few older leaves and a tree that is genuinely deteriorating.

I would pay more attention if:

These signs don’t necessarily mean that the tree cannot recover. They simply tell us that it is worth investigating.

What Can Cause Excessive Leaf Loss?

If leaf loss isn’t part of the tree’s normal growth cycle, I start by looking at its growing conditions.

Light is particularly important. Indoor bonsai need good natural daylight, especially through the darker UK winter months. A position that seemed beautifully bright during July can be surprisingly dark by December.

Watering is another common cause of problems, and both extremes can produce leaf loss. A bonsai that repeatedly becomes too dry can deteriorate, but constantly saturated soil can be equally troublesome.

I don’t recommend watering bonsai to a fixed timetable. The tree, pot size, soil, temperature and time of year all influence how quickly water is used.

Nutrition matters too. Bonsai grow in a relatively small volume of soil and therefore depend upon us to provide the nutrients they require during active growth.

Sudden environmental changes, very dry air, extreme temperatures and cold draughts can also contribute to leaf loss in indoor bonsai.

The important thing is to look at the whole tree rather than diagnosing it from one yellow leaf.

Don’t Forget Pests and Disease

Bonsai are living trees, and just like other plants they can occasionally be affected by pests or disease.

Look closely at both sides of the leaves, along stems, around growing tips and where branches meet. Tiny pests and their symptoms can be surprisingly easy to overlook.

As part of our own preventative care, we recommend appropriate plant protection products or a suitable plant invigorator, always following the manufacturer’s directions and ensuring the product is suitable for the species concerned.

If you can see an obvious pest, unusual spotting, webbing, sticky residue or distorted growth, identify the problem before applying an insecticide or fungicide. Correct diagnosis makes treatment much easier.

Take a Photograph Before You Change Anything

This is probably one of the most useful pieces of advice I can give.

If you aren’t sure why your bonsai is losing leaves, take several clear photographs before making lots of changes.

Photograph the whole bonsai, the leaves that concern you and the surface of the soil. If possible, also show us where the bonsai normally lives.

Then ask the bonsai nursery or bonsai centre where you purchased the tree for advice.

We can often learn an enormous amount simply by looking at a photograph.

Tell them how often you are watering, where the bonsai is positioned, whether it has recently been moved and when you first noticed the problem. The more information you provide, the easier it is to work out what is happening.

Please Don’t Wait Until Your Bonsai Has Died

This sounds obvious, but it is something we encounter surprisingly often.

If a bonsai is clearly deteriorating and you don’t know why, ask for advice sooner rather than later.

A tree that still has healthy tissue and some vigour has a much better opportunity to respond once the underlying problem has been corrected. If you wait until the tree has completely dried out or died back, unfortunately there may be nothing anyone can do.

At the same time, please don’t become anxious about every imperfect leaf.

I think new bonsai owners can sometimes watch their trees too closely. A yellow leaf appears and suddenly everything changes – more water, less water, a new position, some feed, perhaps another move the following day.

Often the bonsai simply needed to lose an old leaf.

If you need to contact us please What’s App photos to 07860 165086 and we shall get back to you as soon as possible.

A Bonsai Tree Is Supposed to Change

Perhaps this is the most important point of all.

A bonsai isn’t an ornament that remains exactly as it looked on the day you bought it.

It grows. It rests. It produces new leaves. Old leaves fall. Outdoor species change with the seasons. Branches extend and need pruning. New buds appear in places you weren’t expecting.

That continual change is one of the reasons I have loved growing bonsai for the past 30 years.

So, if you find a yellow leaf beneath your bonsai tomorrow morning, don’t immediately assume the worst. Look at the whole tree. Look for healthy growing tips and new buds. Consider the species and the time of year.

Sometimes a falling leaf is telling you that something needs attention.

And sometimes it is simply a bonsai being a tree.

Sarah
Bonsai Direct