Do Bonsai Lose Their Leaves In Winter?

It is pretty common for people to panic in winter when they see their tree lose its leaves. However, depending on what tree you have and where you live, this may be totally normal and nothing to worry about.

To find out if it is normal for you tree, you just need to know what species you have and find out if it is a deciduous or an evergreen tree. I will go through all the different tree types below and explain what they should be doing in winter and if it is normal for them to lose their leaves.

Deciduous Trees In Winter

It’s totally normal for deciduous trees to lose their leaves in winter.

Just look around the landscape in autumn and you will see all the leaves changing colour.

Bonsai are just normal trees that are kept small. They go through the same changes as their larger relatives so they will also change colour and drop their leaves.  

When Will They Lose their leaves?

There is no set date for when a tree will lose their leaves.

Trees are very sensitive to the change in temperature and light. As summer comes to an end and the winter approaches, both the temperature and light levels start to drop over the autumn period.

Each individual tree will be slightly different depending on where it is planted as this will affect how much light and what temperature it gets.

This means your bonsai may start dropping its leaves faster or slower than a tree of the same species that is growing in the ground in your garden.

Why Do They Lose Their Leaves?

As the winter approaches the trees know they are going to struggle to grow. It is more efficient for them to pull all their energy back into the tree and wait for the winter to pass. This will also prevent them getting damaged by the cold weather.

The tree sucks the useful energy out of the leaves. The tree takes back the green pigment, leaving only the yellow and reds which is what you see in autumn. The leaves will eventually drop off as they are no longer any use.    

The energy taken from the leaves is stored in the trunk and roots. This energy is usually in the form of sap, which is basically sugar. This extra sugar is diluted into the cells, which makes the water content in the cells lower. This means it is more difficult for the cells to freeze and will therefore not get damaged over winter.

Once the winter has passed, the tree will send the energy back out into the branches to form new leaves in spring.

Will They Grow Back?

Yes, deciduous tree will grow back.

Once spring arrives they will start to bud out. This works in the same way as when the trees loses the leaves. Once the temperature and light levels start to increase, they will start to grow again.

Every tree will act slightly differently so don’t be worried if one tree is slower than another. Give them time and they will wake up.

Semi-evergreen Trees

Some Trees will be classed as deciduous but they are in fact semi-evergreen. This means that they should really drop their leaves, but they don’t.

Chinese elms can act this way. Sometimes, even in the depths of a cold winter, they still have all their leaves.

This is totally normal for some trees and you don’t need to do anything about it.

So long as you have given the tree right conditions and care, it will be fine. It will do whatever it feels is right. You might even find the same tree may only do this some years and may drop its leaves fully on other years.  

Evergreen Trees In Winter

The clue is in the name with evergreens. They should always be green, meaning they do not lose their leaves.

Evergreen will either have needles, like on a pine or a juniper, or they will have more normal looking leaves, like an olive tree.

Evergreens will still lose needles and leaves, but not in the same way as a deciduous tree.

If you ever look closely at an evergreen you can usually see how it has grown over time. You can usually trace the growth down the branch. You can see this year’s growth, last years and sometimes even growth from three years ago.

The three year old growth will just look older and kind of tired. Which I guess makes sense, it’s pretty old.

At some point the tree will decide it does not need these older leaves and they will drop off.

Sometimes this can be all at once in like the autumn or winter, but sometimes it’s just slowly through the year.

These leaves are also usually in towards the center and can have their access to light blocked by the outer leaves. As they get shaded out, they can die and drop off.

This is totally normal. However, if you suddenly find your evergreen has a whole branch that is losing its leaves all at once, or even the whole tree, this is not normal, even in winter!  

You may also find that some evergreens may slightly change colour over winter. This will not be as drastic as a deciduous, but you may find trees like junipers change from vibrant green to a more purple colour, or even sometimes slightly brown.

This is totally normal and the tree will turn a vibrant green again in the spring when its gets more light.

Semi-deciduous

Although I’ve just said it is not normal for evergreen leaves to drop in the winter, it does sometimes happen! 

Some trees are classes as “evergreen” but they are more somewhere in the middle and can act like deciduous trees some years.  Some trees are labelled as this (Semi-deciduous) so you can have a bit of warning that you might get some leaf drop.

Although some trees that are supposed to be fully evergreen may act this way too.  This may mean they lose a large amount of leaves, or all of them.

I myself have had this happen with a few of my trees. I own a couple of privets and they are classed as evergreen. However, mine seem to have been deciduous for the last few winters. They are a popular hedge in this area and I have noticed some of the hedges have also acted like deciduous trees. Luckily my ones and the hedges nearby have all bounced back in spring.

I also own a cotoneaster. A Lot of the varieties are evergreen, but a few are semi-deciduous. I seem to own one of the semi-deciduous as each winter it will lose at least half, maybe more of its leaves. Again, it’s always bounces back.

If you own an evergreen and it seems to act like a deciduous tree in autumn, it can be very scary to watch. If you have been caring for it properly and there is nothing obviously wrong with it (like a pest attack) then there is not much you can do at this point.

Just don’t lose hope and hopefully in spring it will bounce back.  It does happen sometimes.  

Indoor/Outdoor Trees

You should be making sure your tree is growing in an environment that is most like its natural environment. This usually means having them outside as most trees we use for bonsai need this type of environment.

Having trees outside allows them to go through the natural cycles of the seasons and allows them to have the change in weather they require to function normally and go dormant.

When you keep trees inside, they do not get this experience. Even if you put a tree by the window so it gets the natural change in light throughout the year, this is not enough.

Most houses will remain a steady temperature throughout the year and the tree will not sense any change. This means it will not trigger it to drop its leaves.

You may think this is a good thing, but it certainly isn’t. A tree needs to go dormant to be healthy. It needs this time to recuperate energy. If you do not allow for this, it will basically run out of energy at some point and die.

Dormancy is sort of like sleep for the tree. By keeping in inside it is kind of like making it stay away for days on end, eventually it will collapse from exhaustion.   

Tropical trees

Tropical trees are the exception to all of this. They grow in a climate where it’s the same every day of the year. They grow near the equator, so the temperature and day length does not change much through out the year.

They do not go dormant and having a drop in temperature for them is very unnatural and will kill them. This is also why they are usually evergreen. They do not need to protect themselves against the cold so they have no reason to drop their leaves. (old ones will drop off every now and again)

So, if you live somewhere cold and wet like me, tropical trees actually do better inside.

Conclusion

It’s normal for all trees to lose leaves at some point in their lives. Hopefully now you are able to identify if you tree should be losing its leaves in winter or not.

If your tree is doing this at another time of the year I would start to look at the environment you are giving it, or how you are caring for it.

Any tree dropping its leaves at a random time of the year is a clear warning sign that something is wrong and you will need to address it quickly or you tree could die.