Deciduous And Broadleaf Evergreen Bonsai – A General Maintenance Calendar Guide

This article is long and goes into quite a lot of detail around how to care for your deciduous and broadleaf trees through out the year

I will quickly go through the different types of deciduous trees you can get, then go through the 4 seasons and cover what type of work can be done at these different times of the year.

I have tried to break this down into as much detail as possible to try and cover as many different trees as possible, so while some of this information may not be relevant to you, hopefully there is enough that is.

What Are Deciduous And Broad Leaf Trees

These trees are easily identified by their leaves.  When we think of trees you can very generally put trees into two categories those that have needle like foliage and those that have leaves. The ones with leaves are deciduous and broad leaf trees.

Deciduous trees have a whole range of leaves. They can be all sorts of sizes, shapes and colours. However the important thing is that in the autumn the leaves will start to fall off and they will be totally gone in the winter, then grow back again in spring.

Broadleaf evergreens looks very similar, the main difference is that they will keep their leaves all year around. If you look at trees live an olive or an azalea, in the height of summer they look no different than any deciduous tree, but in winter they do not change.

Trees with needle like foliage are called conifers and they are dealt with differently and we are not looking at these here.        

Leaf Pattern Is Important

As I just said, the leaves can be in all sorts of sizes, shapes and colours. However, how they grow will fall into two different patterns. This will become important later when I discuss how to prune the trees so it is important you know what your trees leaf pattern is.

When you look at branches from different trees you will very easily be able to see two different growth patterns. It is important to be able to recognise these and know what you have.

Alternating Leaf

When you look at the leaves you will see they are staggered up the branch on alternate sides. One will come out to the left side and the one above it will then come out to the right side and it will follow this pattern all the way up the branch.

The majority of trees will have this alternating leaf pattern.

Opposite Leaf

These leaves grow in pairs. On a branch a leaf will come out to the left and the right at the same spot. The next pair of leaves will do the same and these pair of leaves will be how the tree grows.

Dealing With Deciduous Tress In Spring

In spring your trees will start waking up after and there is plenty of work to be done at this time of year.

Repotting

If you are repotting your tree, this is the time of year it should be done. (You can read more about- When To Repot A Bonsai)

You need to do this as the tree starts to waken up and the buds start to swell. You should repot just before they are about to open. Different trees will do this at different times as it depends on the weather, tree species, the trees age and health among other things. This means you just have to pay close attention to each tree you own and watch them all to see when they are ready for a repot.  

If you are lucky enough to own an older tree (anything 30/40yrs old and beyond) it can be better to wait a little bit longer until the buds are pretty much open before you repot. These types of trees can be a little weaker so by waiting a little longer will make sure they are going  to open their leaves immediately, if not already, which means they can instantly start sending energy down to the roots and start recovering immediately from the repot. Since they can be weaker, any help like this to stop them becoming further weakened is helpful and will hopefully prevent dieback.

Also remember to use good soil when you are reporting. Typically you will see soil mixes of 50% akadama 25% lava rock 25% pumice. Deciduous trees can take a little more moisture in the soil than conifers but you should adjust depending on your climate and what you have available

(You can read more about – A General Guide To Bonsai Soil)

Spring Growth Management 

In spring your trees are going to explode with growth and you need to make sure you manage this properly. I will quickly explain what is happening inside the trees with their hormones, so you can get a better understanding of what needs to be done.

The Hormone Exchange Process During Spring Growth

Understanding the exchange of hormones inside the tree is really important, but I will keep it simple.

In spring as the new shoots are extending and the terminal buds are filled with a hormone called Auxin. As the tree grows through spring, this hormone is sent back down into the tree and down into the roots through a process called “Polar Auxin Transport”.

This auxin being sent back down will then interact with another hormone called Cytokinin, which is being pumped up to the shoots from the roots.

This up and down movement of these two hormones is called “crosstalk” (this actually happens in all trees) and this process is very important for the trees growth and development and we should not disturb this.

Don’t Prune The Tree In Spring

So the whole point of getting a little scientific there is to explain that if we go in and prune our trees at this time of year …it can be bad.

If we prune back now we are going to cut the tips off, so we lose a lot of the auxin. This means no hormones are going down to the roots, so the root growth is affected and of course top growth is then affected (since we removed it).

This basically means pruning in spring is a bad idea. No matter what your are goals are we should allow everything to grow freely and really elongate in spring to make sure our trees stay healthy.

Japanese Maple Pinching

There are of course exceptions to this, Japanese maple bud pinching being the main one. This is when you remove the buds from a new shoot. You let one set of leaves come out and then pinch the rest of the bud.

I’ve just said that doing this will remove the auxin and hinder the growth, which is true. This is why you only do this method at certain times. You would only do this once every few years on a very healthy tree that you are trying to develop ramification on. You would also not do it at the same time as repotting.  You would not do this every year and you would not do this on a young tree you are trying to thicken. For these, you need to just let them grow like any other tree.

Spring Fertilisation

Fertilisation is of course important for trees in spring, but how much to give and when this should be dictated by the stage of development that the tree is in. If you have just repotted your tree, give it a few weeks to recover before starting to fertilise.

Young Trees

You should give these trees a high nitrogen fertiliser. This will give them a lot of growth and allow them to thicken. You can happily use strong chemical fertilisers on these trees.

Just follow the packet instructions. You can easily over fertilise and give too much nitrogen to the roots, which will damage them, espcially if you have repotted the tree so just follow the packet.

Semi Developed Trees

These are the trees where the thickness is almost there and you might be starting to look towards developing ramification.

You should hold off fertilising these trees in early spring. The lack of fertiliser will give you smaller leaves and tighter internodes, which is exactly what you want when you are starting to build ramification.

However, make sure you still let all the shoots elongate during spring.

Once the leaves harden off in late spring/ early summer you can then fertilise. At this point the size of the internodes and leaves are not going to change so adding fertiliser will not affect this.

You can also change from a hardcore nitrogen heavy fertiliser into something a little lower.  You can also move away from chemical products and start going more organic fertilisers, which usually contain micronutrients that are going to help you tree at this stage.

Developed Trees/ In Refinement

You should treat these trees the same as a semi developed tree.

Do not fertilise at first. Wait until late spring when everything has hardened off and then start fertilising from then.

However, for these trees you should use low nitrogen fertiliser (something like bio gold). You should aim to keep the nitrogen below 10.

This lower level of nitrogen will make sure the tree gets everything it needs without allowing the growth to get too out of control.

Spring Fungicides and Pesticides

Spring is a good time to use fungicides and pesticides.  I would avoid using leaf sprays on the young leaves as this can easily damage them.

You should use systemic granular products. These get absorbed into the tree when you water and will kill anything that tries to eat your tree.

At this time of year the tree will be moving a lot of water so these fungicides and pesticides will really get into the whole tree quickly.

Dealing With Deciduous Tress In Summer

By summer your trees should be happily growing, but there is plenty of work that you can do at this time of year.

Summer Growth Management 

For pruning deciduous and broadleaf evergreens we need to split them into the different leaf patterns I talked about at the start, as how you manage each type of tree is slightly different.

Managing Alternating Leaf Trees

By late spring, into early summer the new leaves should have hardened off. This means that the colour is usually now darker than the bright spring growth and the texture should be waxier and firmer at this point.

Each branch should have around 6-8 leaves at this point (For a lot of people this is usually around May, but it will depend on your climate and your trees).

What we do next depends on the long term goal with the individual branch.

If you want the branch to thicken… let it grow. Don’t touch it. It’s as simple as that.

If you want to start develop ramification and movement. Then you need to prune it back. Pruning will promote a second flush of growth, but more importantly you will get more than one shoot, which means your one branch will turn into two. This is how you get ramification; you just repeat this for many years. 

You Should Prune Back To 2 Or 3 Leaves

When you look a branch, and then look at the new growth, you will find that the first leaf is nearly always a weird shape and if you look closely, it doesn’t have a bud at the base of the stem.

So basically you can ignore this leaf and then start counting from the next leaf. This leaf is your “number one”. You can then count to 2 or 3 from here.

The reason why you might go to 3 leaves, rather than 2, depends on direction your leaf is pointing. Basically you want to cut to a leaf that is pointing out and away from the main tree.

You also want to avoid leaves that are pointing straight up. Of course you can wire things and change its direction, but if you can cut to a leaf that is facing a good direction this will be easier.

This is often called clip and grow and you will find that whatever direction the leaf is facing, your new shoot will grow in this direction too. 

You can also remove that first weird leaf as it isn’t really dong much. This will allow more light into the inner structure so can help promote back budding in this area.

Once you do this cut back you can start to fertiliser as described above in the spring section (there is slight overlap between late spring and early summer, it will all depend when your new shoots actually harden off).

Defoliation

Defoliation is also possible at this time of year. This is the process of removing all, (or a large majority) of the leaves.

However, it is important to know that not all trees can be defoliated, or partially defoliated.

Trees To Avoid Defoliation

I would avoid defoliating trees like beech, hornbeam, crab apples and cherry (you should check you individual species to see if it is possible). When you defoliate these trees, the energy goes crazy in the tree and is no longer spread out equally. Some branches shoot out and have huge leaves, others will be tiny and some might even be normal sized. You will also find that some branches might not even reshoot out again, which obviously puts them at severe risk of dying.

Trees To Defoliate

If you have a tree that can handle defoliation such as elms, zelkova, apricot and quince then this process can be carried out at the same time pruning that I have discussed above. (Again, you should check if your specific species can be defoliated).

Defoliation will lead to smaller second flush of growth, as well as development of finer branching/ ramification. This is a very good technique for starting to build really strong ramification.

Once you cut the tips back as described above you can also remove most of the leaves. You should focus mainly on the stronger outer leaves.

You can leave the most inner small leaves to allow them to develop.  After a few weeks new shoots will develop everywhere you removed leaves.

Once you defoliate you should not add fertiliser. This technique makes the tree act like it is early spring again and its going to push out new buds. If you want this new growth to have small leaves and small internodes then give them no fertiliser.

Again, you should wait until the new shoots have elongated then hardened off, and then you can begin to fertilise again.

Managing Opposite Leaf Tree

Opposite leave trees are very similar, but there are some subtle differences. The most common tree you will come across that has this leaf structure is maples.

Again you need to wait until late spring or early summer when the new leaves have hardened off. This will again be in and around May and you will find there are 6 to 8 pairs of leaves. 

When you look at the branch you will see again that the bottom pair of leaves are often weirdly shaped and don’t always have buds at the base of the leaves. If this is the case, you can again ignore these leaves, and even actually remove them.

Move up the branch until the next internode, where you will find a pair of leaves. This pair is your first set of leaves and you can count the pairs all the way to tip. You want to cut back, leaving to 2 or 3 pairs of leaves on each branch.

You will find that where ever you cut, the leaf pair directly below this, well send out a new shoots on each side, so you will always get two shoots. (Some trees get excited and can send a few, but there should always be at least 2)

You can again cut the shoots back to a pair of leaves that are facing a good direction so that when the new shots emerge they grow in this direction.

Once the new shoots come in, you can fertilise the tree once these have hardened off.

Defoliation

The defoliation of these trees again comes down to ones you can, and ones you cannot, so you need to check your individual species to see if it can handle it.

Trees To Avoid Defoliation

The main tree in this category is Japanese maples; there will be others that have alternate leaves but you need to check if they can be defoliated of not.

You can prune these in late spring when the first flush of growth has hardened off, but I would not defoliate Japanese maples. They can often become very weak and branches may die if you do this.

Trees To Defoliate

Trees such as trident maples can be defoliated with no trouble. They should be treated like alternating leaf trees. You can cut them back when the spring growth has hardened off and then defoliate them at the same time.

You can pretty much defoliate a trident yearly, sometimes even a few times a season. They are really hardcore and are very aggressive growers. 

You just need to remember that you should not fertilise until the new flush of growth has hardened off. (So if you defoliate more than once, wait until the last time you do it, let the new leaves harden off and then fertilise).

Hard Cut Backs

If you want to make any large cuts to the tree, you can do this in early summer.

In spring there is too much water moving through the tree and it will cause too much bleeding of sap if you make large cuts at this time.

Once the first flush of leaves has hardened off by late spring, the main movement of water through the tree is done. The tree will now just be in the growth cycle; it will still be pulling and pushing water up and down, but nowhere near as aggressively as in spring.

This means that now you can do any hard work on the tree and it will not be troubled by it.  I would just try and avoid making any cuts bigger than 2 inches in diameter. These can be massive for a small tree and it can be almost impossible for them to ever fully heal.  

As many of you are aware, I prune a lot of my trees back at the end of winter, almost early spring, just before they wake up. 

This is fine for small pruning, but not ideal for large cuts as the tree is not growing; (even if it’s only a few weeks, maybe even days) everything around the wound can dry out and can actually make the wound bigger.

Personally I have small/young trees and my “big” cuts are maybe 1cm across, I know my overall trunk thickness is still in development, so I know these wounds will heal. I am happy to prune my trees in the winter and so do many other people.

However, it is common to see Japanese nurseries prune their trees and make these hard cuts in the early summer. Again, once any spring growth has hardened off, you can start making cuts.  

If you do make any big wounds, you need to let the tree grow out a bit to help these heal.

Summer Fungicides and Pesticides

In late spring or early summer once everything has hardened off you can start to use spray fungicide and pesticide. It will not damage the leaves at this time. Just follow the instructions for whatever product you are using.

Dealing With Deciduous Tress In Autumn

In autumn everything will be slowing down and most of the work will be finished for the year. It doesnt matter what type of leaf pattern you have now, all the trees can be treated the same way in autumn.

Fertilisation

There is myth that you should not use nitrogen heavy fertiliser in the autumn as it is going to produce new leaves that will end up dying back when it gets cold, or the tree will try and reshoot when its shutting down and mess up its dormancy.

The reality is that is not true. Nitrogen cannot make a tree bud out. Trees bud out when you prune them.

In late summer early autumn the tree has already got the buds ready for next year. If you start pruning at this time of year, the pruning is going to stimulate the back buds to start shooting. Which you really do not want at this time of year as it will die when it gets colder.

You should not be pruning at this time of year, but you should be using a nitrogen fertiliser. This is going to get the soil and tree rich in nutrients which will be used in spring. You are fertilising in autumn, to give the tree energy in spring.

If you remember we are not always fertilising trees in spring, so by doing so in autumn, it gives them enough to stay healthy during this time.

Pruning

As above you should not be pruning at this time of year as you will cause the buds to shoot out. However, once the tree is fully dormant and has lost its leaves, you can light prune, but avoid large cuts during autumn.

The tree will not be growing now until spring so you really should not do a lot of work at this time.

Dealing With Deciduous Tress In Winter

In winter your trees will be dormant, so there is not much to be done. The trees will just be resting until the spring.  

Winter Fungicides and Pesticides

From late autumn into early winter you can use lime sulphur as winter protection. You can dilute it with water and spray it on your trees. This will kill any pests or fungus that might be living on your tree. Hopefully the frost at this time of year should get most things, but this is an extra layer of insurance.

I personally don’t do this. I live in a very mild area and there are not many pests around so I am not too worried, but if you live in other parts of the world this may be a good spray to use to give you some peace of mind over winter

Hard Cut Backs

As I’ve mentioned in the summer section of hard cut backs, I do a lot of cutting back right at the end of winter. Again, I live in a mild climate, mixed with having a lot of young trees, so I am happy to prune at this time of year as I know spring is very close.

You may want to prune in the summer, depending on what you are trying to achieve and where you live. If you are unsure, I would try and find out when people in your area like to do hard pruning and follow their lead.   

Conclusion

There is a lot of information in this post, but hopefully now you can manage your deciduous and broad leaf ever greens through the year and know what you should be doing.

Feel free to bookmark this page and come back to it often, like a calendar you can check what you should be doing with your bonsai each season. 

(You can also read more about How To Plan and Track Your bonsai)