Frequently Asked Questions About – Repotting Bonsai

Repotting is a pretty important part of bonsai, but I think it is often misunderstood, simply based on how many questions I get asked around this topic.

I have covered the When and How in separate articles, which will be linked throughout this page, but I still get asked a lot of good questions around the topic of repotting, so I have complied them all here.

It is kind of long, but it should help you out. If you are still unsure about something just ask and I can add it to the list.  

How Often Should I Repot My Bonsai?

I get asked this question a lot, and the reality is that you need to repot the tree whenever the tree needs it. You do not need to schedule this from a calendar, but instead look at the tree and see all the signs that it may be ready to be repotted. 

Really in the majority of cases this will be when the pot is root bound and there is no more space for the tree to grow and be healthy, so you have to go in and deal with that.

I cover how to spot this, as well as the other signs that your tree needs to be repotted and is ready for it in this article – When Do You Need To Repot A Bonsai?

If you read that, you should know exactly when the right time to repot is.

What Precautions Should I Take When Repotting A Bonsai?

There are many precautions you should take, but really the two main things you need to worry about are the health of the tree and the time of the year. If these two things are correct, then you should be fine.

You need your tree to be healthy and strong enough to handle the work you are about to do. Some repots can get pretty drastic so you need a healthy tree to be able to cope with it.

The time of year is also hugely important and you can use this to give your trees health an advantage. You need to be repotting just as the tree is waking up and its buds are swelling in spring.

If you time this right the tree will have moved all its stored energy out of the roots and then when you cut them back, it doesn’t really affect the tree negatively, although you do want the tree to be healthy in the first place, so it actually has this energy to start with.

What Type Of Soil Should I Use When Repotting A Bonsai?

Ideally you want to use good bonsai soil when you repot. This is going to help give your tree everything it needs and keep it healthy, while also developing the best roots possible.

What exactly “good bonsai soil” means will depend on your and what you have available to you.

However, I cover this in depth in – A General Guide To Bonsai Soil – so you should read this to make sure you fully understand bonsai soil and learn what you actually need.

How Do I Remove A Bonsai From Its Old Pot Without Damaging The Roots?

Getting your bonsai out of the pot is either going to be extremely easy… or difficult. This really all comes down to the shape of your pot and if it has a lip or not.

If you have seen any of my videos on YouTube you will see that this is the case, some root balls slip right out and other are a real battle.

If your root ball is stuck, you will have to cause a little damage to get it out, but this is nothing to worry about. Half the problem will be that there are too many roots and the majority of them are not helping your tree. You are going to have to remove these, so if they get a little damaged when getting the tree out of the pot it is totally fine.

However, when I say “damage” it’s is not going to be anything really noticeable. You will see I often scrap away a lot of the soil and even sometimes run a knife around the lip of the pot to help free the pot. When I do get the roots out, there may be a little scratch or mark here or there, but overall the damage is not too bad …the real damage comes when I get the scissors out and start chopping everything back.

Basically pulling your tree out of the pot isn’t really going to cause much damage. Your roots are going to be well held together and tightly packed and not really move much. You are really only going to cause damage to the roots if there is not enough of them. They may tear when you move the tree …but if your tree is in this state, then it doesn’t need repotted, so you shouldn’t be disturbing the root ball anyway. 

Can I Repot My Bonsai Into A Larger Pot?

You have three options when it comes choosing the size of pot should repot your tree into. You can either go larger, small …or use the same pot.

Which one of these is best will of course depend on your tree and what you are trying to achieve with it.

I cover this in a lot more detail here – Should You Use A Smaller Or Larger Pot When Repotting A Bonsai?

How Do I Choose The Right Sized Pot For My Repotted Bonsai?

The size of the pot you choose will depend on what you are trying to achieve with the tree, as well as the size that the tree is now.

You need to always consider the trees health and balance these with your goals, I have covered this all in more detail here – What Is The Right Size Pot For Your Bonsai?

Should I Prune The Roots When Repotting A Bonsai?

When it comes to pruning the roots, this is optional, but I would imagine that in 99% of instances it will make sense to prune them.

You goal is to get a compact dense root ball and usually when you leave roots alone they do the opposite of this. You will find that most time you go to repot your tree the roots are going to be super long, and maybe even thick, which is not what you want.

What roots you prune, and how much you prune them will really depend on what you have on front of you, as well as considering the trees health and ability to handle pruning along with your goals.

Should I Use A Specific Type Of Pruning Technique When Repotting A Bonsai?

The pruning of the roots look pretty easy and you may even think it’s quite mindless when you see some people doing it …you just hack everything back and that’s it …which isn’t the case.

You do need to pay attention to what you are doing and is pretty similar to how you prune the top of the tree. There are certain things you need to be looking out for, it is just that once you do it a few times you can do this pretty quickly.

I have covered this all in my – How To Repot A Bonsai Tree article, which tell you what roots you need to be cutting and why.

Should I Remove Any Dead Or Damaged Roots When Repotting A Bonsai?

Dead and damaged roots serve no purpose in your bonsai pot. They are just taking up space that could be occupied by healthy roots, so you should remove them.

On very rare occasions dead roots may be some sort of feature you want to keep and display, but these are going to be above the soil …so you can see them, so they don’t take up any valuable space in your pot.

How Deep Should I Plant My Bonsai When Repotting?

When it comes to the depth you should plant your tree, this really comes down to your personal preference.

You need the tree to be deep enough in the pot that the soil actually covers the roots, but you also want it to be high enough so that you can see some of the roots and how they spread away from the trunk and into the soil.

This is all about balance and is something you will have to play around with to see what you like. You also need to consider that the higher you plant your tree, the more space there will be below it for roots to grow, and of course the opposite of this is true too, the deeper you plant it, the less space the tree has below it to grow roots.

If you plant things too deep, you will not see any roots and just have a trunk poking out of the soil, but you will also cause some of the roots to end up growing upwards, and above the main root spread, simply as there is nowhere else to go and this area of soil is free.

Sometimes deeper can be okay, but you just need to find that balance between what looks good and what will keep the tree happy.

How Do I Prevent Root Damage When Repotting A Bonsai?

Some root damage is always going to occur when you are repotting a tree, but this isn’t something you should really worry about. In most cases you will be pruning the roots, which is a controlled formed of damage.

Most of the accidental damage is going to be caused when you are getting the root ball out of the pot and then raking the soil out. The roots are going to be tangled and your rake will tear some of them.

However, even this damage is okay, as it is going to help you get rid of all the roots going in crazy directions and if they are going in a radial direction they are not going to get damaged by your rake, as that is the direction you should be raking.

I usually find that anything that does get damaged is stuff I don’t want or need, and everything I actually want to keep is fine. Then of course I may still prune some of these roots back, but this is how we develop out roots.

Damage isn’t something to worry about, so long as you are in control and what you want and need doesn’t get damaged.

How Much Space Should I Leave For Root Growth When Repotting?

You will need to leave some space in your pot for the tree to grow into. How much space you give the tree will depend on your goals. If you are trying to develop the tree or just let it grow wild, then the more space the better. If you are trying to refine things then you may want to make things a little tighter.

However, you can’t just prune the tree to fit into a small pot, if you have to prune the tree to the level it can handle, then if this fits in your pot, great …if not you will need to find a larger one that it can fit in to.

Always remember that the trees health comes first.

How Long Does It Take For A Bonsai To Recover After Repotting?

How long it takes for the tree to recover will really depend on the species you are using, how much work you did and generally how healthy it is.

As you should be repotting just before the leaves open, it shouldn’t take too long. Within a couple of days your leaves should have opened and then the real healing can begin.

I would say that after about a month, maybe 6 week at the max, the tree should be pretty much recovered or at least showing some signs that it is getting there.

Your aftercare is also going to affect how quickly it can recover, so if you haven’t already, you need to read –  Repotting Aftercare Advice For Your Bonsai

Should I Keep My Repotted Bonsai In Shade Or Sun?

In theory you should put your tree in the shade, but I think this really depends on your environment.

If we look repotting season, it is very early spring and the temperatures and general level of sun are not exactly very high …but this is why I said it depends on your environment. For me, this is the case. I can repot a tree and just leave it in its normal spot. The sun isn’t really that strong and if anything, it’s probably the perfect level for the tree.

If I am going to protect my tree from anything, it is going to be the wind, but you really need to look at your own climate and if you feel the sun is a little too strong, then protect your tree by placing it in some shade until it recovers.

Can I Repot A Bonsai That Has Recently Been Watered?

You can repot a bonsai that has recently been watered, but to be honest it’s not ideal. It just makes things unnecessarily messy.

If you want to do things right, wait until the tree is ready to be watered …and instead of watering it, repot it.

This will mean your soil is slightly dry, it shouldn’t be bone dry, it will still be damp, but it will be a lot drier than right after watering it. This will just allow the soil to fall away much easier. When soil is wet it is sticky and dirty and just annoying.

It just makes everything a little harder when its wet, especially when you go to rake everything out. You will notice a difference, so where possible don’t water immediately before repotting. 

Can I Repot A Bonsai That Has Recently Been Fertilised?

This is a trick question …because why are you fertilising?

If your tree is growing and you are adding fertiliser …well your tree is growing, so don’t repot it. You have missed the window of opportunity.

However, if you are fertilising your trees over winter and it is now early spring and everything is waking up …my question to you is …why are you fertilising in winter?

If you tree is not actively growing then the fertiliser is a waste of time, it doesn’t do anything. The tree is dormant is not using any of it. Although, if you have been fertilising your tree all winter long and it is now waking up, you can still repot it …just don’t waste your fertiliser next winter. Keep it for the growing season.

Should I Use Fertiliser After Repotting A Bonsai?

You should not use any fertiliser on your tree for a good 6 weeks after repotting it. All the roots you have cut need time to heal and adding fertiliser will not help with this and can in fact damage the roots, so don’t do it.

If you do want to add anything to your trees to help them recover, add Rhizotonic, which is a special formula made from algae that is designed to help promote root healing and growth …which is exactly what you want after repotting.

Rhizotonic is really the magic repotting juice, not fertiliser.

(You can read more about – Using Rhizotonic On Your Bonsai)

Should I Use A Rooting Hormone When Repotting A Bonsai?

Root hormone is used to help cuttings take root and you don’t need it when you are repotting a tree.

When you add it to your stem cutting, you are basically telling the wounded area “roots need to be here! grow roots! right here”. Normally this area would just heal over with bark, since it’s just a branch, but the hormone basically over rides this and tells it to grow roots instead. 

The hormone doesn’t help the growth of roots directly… it just tells the tree what it needs to be doing in that area and then the tree grows accordingly.

When you are cutting your roots on your bonsai, the roots are already full of this hormone …you don’t need to tell the roots to grow roots. It is going to do that anyway, so adding extra hormone is basically a waste of time.

How Do I Prevent Pests And Diseases When Repotting A Bonsai?

Diseases and pests are sometimes unavoidable, but they are also more frequent at certain times of the year, and luckily this isn’t really during repotting season.

I have thankfully never had a problem at this time of year, but I do know some disease spores can be in the air. All you can really do is keep your tree healthy and repot it at the right time. If you time this correctly then the tree will start healing itself very quickly and the risk of having a problem will be much lower.

If your tree is already suffering from something when you go to repot …I would deal with the problem first. You tree is going to be weak and ignoring this and repotting is only going to make things weaker. This does mean you will miss the window of opportunity and not get to repot the tree, but you need to deal with that pest or disease first!     

Can I Repot A Bonsai In The Winter?

You can repot a bonsai in the winter… sort of.

The exact time you repot is not important; you need to look at the tree not the calendar.

When the buds start to swell and are just about to open, this is the best time to repot. For some trees this is going to be late winter, very early spring.

However, you need to be careful with these trees that like to wake up early. You need to check the weather for potential frost.  There is no point repotting it, only for it to die a few days later when the frost comes.

This can make things tricky as the tree is ready for the repot, but if the weather is still too cold you have to wait. If you can shelter the tree, then this is perfect. You can repot the tree and then protect it in your green house or wherever until the frost is gone.

Can I Repot A Bonsai That Is In Full Sun?

If you are repotting at the correct time, which will be early spring, the sun is not to strong. I know where I live it is not to strong and I would imagine for those in hot climates, it would still be quite weak at this time of year.

Repot your tree when it is ready to be repotted and the buds are just about to open …and then if you feel your sun is particularly strong, you can place the tree in some shade for the first few weeks until it starts to recover.

Can I Repot A Bonsai During The Summer?

You shouldn’t be repotting trees in the summer. You need to do this when they are waking up after winter and the buds are about to open.

However …some tropical trees can be repotted in summer. Things like jades and even ficus can handle being repotted in the summer. You just need to protect them from extreme sun light and heat for the first week or so after repotting them as they will not be able to handle it as well as they usually can.  

Can I Repot A Bonsai That Is In Bloom and Flowering?

If your bonsai is in flower, or it is the flowering season … it’s probably too late to be repotting the tree.

You should only be repotting in spring, just as the leaves are about to open. On some trees, the leaves and flowers may open at a similar time, or maybe even the flowers open first …however, it doesn’t matter, if they are open, it’s too late and you have missed the window of opportunity.

If you watch any of my videos you will see I repot just as the buds are swelling and are days away from opening up. This is the best time to repot. If you do it here, the tree will not even notice it has happened.

Can I Repot A Bonsai That Is In The Middle Of Leaf Drop Or Dormancy?

If your tree is in the middle of dropping its leaves and going dormant …this isn’t a good time to be repotting.

The tree is going to be shutting down, so if you start hacking parts off the roots, it isn’t going to be healing its self. You are then going to have a lot of wounds just sitting there all winter long, which is really not ideal.

You need to wait until spring until the buds about to open, any time outside of this is will usually end in trouble.

Can I Repot A Bonsai After It Has Been Styled?

You can repot a tree after it has been styled, but I would suggest you ask yourself how much work you have actually done. It is common to do work in late winter, especially pruning and styling, which would be just before it is time to repot the tree. 

If you have really done a lot of work and really pruned a lot and bent a lot of branches …this is going to have stressed the tree, so ideally you want it to recover from this before you start doing more work and stressing it further, so repotting may not be the best idea.

If you have only done a light bit of work, then it can probably handle both sessions so close together.

It will really depend on the tree you are working with and how healthy it is. If you have any doubts then you should space the work out.

This is really common with trees like junipers where one season you will work the top of the tree and the next season the roots. Spacing the work out like this is slow, but it allows the tree plenty of time to recover and regain strength in between your work.

Can I Repot A Bonsai That Has Recently Been Moved To A New Location?

This is an interesting question. This really depends where the tree has been moved from and of course what time of year it is.

You firstly need to make sure it is the right time of year and that the tree is showing signs that it is ready to be repotted.

Then I would argue that if the tree has come from a fairly similar environment to yours, then it should be fine. If your friend from 10 miles away brings a tree from his garden to your garden, that is not really going to be a problem, your environments will be pretty much the same.

However, If the tree is coming from inside, to outside, this is more an extreme environmental change and I would suggest you let the tree properly acclimatise before repotting it or doing any other work. 

Any sudden or drastic change in environment is really going to stress the tree and repotting will only make things worse, so give it time to settle in and then when it is comfortable, you can repot it when the next opportunity arises (when it is waking up after winter)

How Do I Create A Suitable Drainage System When Repotting A Bonsai?

The only drainage system you need for you bonsai is a pot with adequate drainage holes and good soil. So long as you have this, everything will be fine.

The soil will let excess water pass through and it will only hold on to the moisture it needs, then the drainage hole will make sure anything extra can escape out the bottom of the pot.

It really is that simple, you don’t need to make things any more complicated than this.

Should I Water My Bonsai Differently After Repotting?

The short answer is yes, you probably will water it differently, but your technique will pretty much be the same.

How the tree interacts with the new soil is going to be very different from before you repotted. You are probably going from a compact soil, full of roots, to a very loose soil that is not full of roots.

It can be a little difficult to work out if your tree has enough water or not at first, but if you pay attention and focus you will be fine.  

If you know how to water correctly this will not really be an issue for you, you can see what the tree is telling you and adjust your watering accordingly. You will need to be dynamic with your watering for the first few weeks until the tree recovers, then you should start to find a rhythm with things again.

You can read about this in more detail – How To Water A Bonsai After Repotting

How Long Should I Wait To Water My Bonsai After Repotting?

You should be watering your bonsai immediately after you have repotted.

Once you have the soil in the pot and have worked it into all the gaps and you are satisfied there is no more space in the pot …water the tree.

Water it until the water starts coming out the bottom. It will be dirty looking as it will be full of dust particles. Keep watering until the water runs clear.

You can even come back 30 minutes later and do the same again, to make sure that everything is actually wet and settled in.

Then from here, you water as normal, look at the tree every day and see what it needs and give it water if you think it needs it.

Can I Repot A Bonsai That Has Recently Been Through A Period Of Extreme Weather?

This is a bit of a yes and no answer. The only extreme weather your tree should be exposed to before repotting is winter.

If you tree has just gone through a tough winter …but it is now waking up and the buds and swelling and the weather is showing no more risk of frost, then this is perfect. Your tree has survived and it is ready to grow and it is the perfect time to repot.

If your tree is going through any other sort of extreme weather …then it is the wrong time of year and you should not be repotting anyway so it doesn’t matter. Let your tree recover from whatever it experienced and it should be fine to repot the following spring if you think it is strong enough to handle it.  

Can I Repot A Sick Bonsai?

Repotting a sick bonsai is pretty dangerous. You really need to ask why the tree is sick and then ask if repotting is going to help this or make it worse.

If you tree is sick because the roots are too compact and it can’t get water, or the soil is just awful and making things bad …then repotting makes sense. However, how much work you do is probably not going to be as drastic as you want.

You need to be careful if you do end up repotting the tree, as really anything you are doing is going to weaken the tree, which is not ideal if the tree is already sick.

This is why you really need to ask if it is necessary, changing the soil from dreadful soil to good soil is going to weaken the tree, but only temporarily, eventually it will benefit from it more, so the risk is worth it as to do nothing is certainly going to only make things worse.

Can I Repot A Bonsai That Has Recently Had A Pest Infestation?

So long as your tree is healthy and you think it is strong enough, then repotting should be fine.

You should only be repotting after the winter, when the tree starts to waken up. Most pests will die over winter, so they shouldn’t really be an issue at the time of repotting. However, I would ask yourself how healthy the tree was when it went dormant.

If you think it was okay and had plenty of energy, then it should be fine to repot. If you think it was pretty weak and just barely survived, I would maybe not repot it and let it use all its energy this spring to recover.  

Can I Repot A Bonsai That Has Recently Had Its Branches Pruned?

Yes, you can reopt a tree that has its branches recently pruned …but this only applies to winter pruning.

If you look at any of my videos I do this a lot. My trees are dormant and right at the end of winter I prune them back. This is usually mid/late February for me.

I do this here as I know within the next few weeks the tree will wake up. All the energy will come back into the tree and the buds will start to swell. The energy is only going to into the areas I have left after pruning and it is almost like the tree hasn’t noticed it has sections missing.

Once the tree wakes up, you can safely repot it without any issues.

If you are pruning your tree at other times of the year, and then you want to repot …this will end badly. You will weaken the tree and probably kill it. 

Can I Repot A Bonsai That Has Recently Had Its Foliage Trimmed?

You should not be repotting a tree that has foliage. If you tree is growing like this, then it is too late in the year. You need to be pruning just as the new buds are starting to open.

I am sure some of you will ask about evergreens. These are slightly different. They will still go dormant in winter and when they wake up they will still produce new buds in spring, so you treat them the same and repot them at this time.

This can mean that you end up pruning some foliage off in winter …but you will still see the buds forming as they wake up a few weeks later. It’s pretty much the exact same, it’s just that they may already have some leaves. 

I would also do the same for tropical trees, they will slow down in winter and if you prune them here, they will still produce new buds too, so you would treat them the same and repot them here as they are starting to wake up again.

Can I Repot A Bonsai That Is Currently Experiencing Leaf Yellowing Or Browning?

If your tree has yellow or brown leaves, it is either autumn or something is wrong with your tree that you need to fix.

Either way this is not the right time to be repotting. You should only be repotting when you tree is waking up after winter and the buds are starting to swell and are about to open.

Even if your tree is an evergreen, the leaves will not be yellow or brown at this point and if they are, then you may have a different issue going on that you need to address. This may be due to the soil/roots and maybe a repot will fix this, but this is really something you need to investigate and then decide what the best action is.

Can I Repot A Bonsai That Has Recently Been Exposed To Chemical Sprays Or Pesticides?

Any sort of chemical spray or pesticide should not really harm the tree. They are designed to only harm the pests.

If you have just been using these for preventative measures, then it should be fine. If you have been spraying these because you tree has some sort of infestation, then you should ask if your tree is strong enough to cope with a repot, and if you feel it is not, then do not repot.

Can I Repot A Bonsai That Has Wire On Its Branches?

You can repot a tree that has wire on the branches, this shouldn’t be a problem.

If you are making extremely drastic bends and really changing everything about the tree, then this may shock the tree a little bit and it might be best to let it recover and avoid repotting. However, in most cases it will be fine.

I would recommend that you do the two activities separately though. Don’t wire and repot the tree on the same day, that might be too much for it. 

I would probably wire the tree in late winter, when the tree is still dormant. The closer it gets the tree waking up, the more you risk damaging the new buds. I also wouldn’t wire soon after a repot, as the tree will be unstable in the pot and new roots will be forming. These are all very delicate and if you start bending stuff you will shake things up and damage the new roots.

Can I Repot A Bonsai That Has Recently Had Its Wire Removed?

You can repot a tree that has had its wire removed recently. This will not be a problem.

When you remove the wire, the branches are now set in place, so removing the wire doesn’t affect anything, it just insures it cannot bite in and cause damage.  

You could remove the wire and repot in the same day … although I would still say don’t. Try and remove the wire in late winter before the buds are swelling. It can be easy to knock the buds off when you are removing the wire, so I wouldn’t risk it.

Can I Repot A Bonsai That Has Moss On Top?

You can repot a bonsai that has moss on top.

What you do with the moss is up to you. Usually I just throw it away as I live in an environment where moss just grows no matter what.

If you want to keep it and put it back into your pot at the end, you can. You just need to squish it down on to the new soil and within a few weeks it will have taken hold and be growing like it was before.

Conclusion

There is a lot of information above on repotting, so hopefully now you have all the knowledge you will ever need, but if for some reason you are still not sure about something, just ask.

People get scared about repotting, which is fair enough it can be quite risky if you do it wrong …but if you do it right, your tree will not even notice it has happened and just bounce right back stronger than before.