If you want your Bonsai to be healthy and keep thriving, make sure you re-pot it regularly. As your Bonsai keep on growing within a pot, it consumes all the nutrients from the soil present in it. In this post, you will learn how to repot Bonsai seedlings and trees step by step, and Bonsai repotting aftercare.
Repotting Bonsai is crucial. Otherwise, being bound to the same pot will starve the Bonsai seedling and trees. As you provide it greater pot space and a fresh supply of nutrients and soil, Bonsai continues to grow and flourish.
Moreover, the roots start to grow the shape of the pot with time. Now, as the plant keeps on growing, the nutrient supply and space to adjust its roots starts to reduce. If it remains within the same pot, it will stop growing further and even die due to a lack of nutrients.
When to repot Bonsai seedlings and trees?
It is ideal to re-pot the Bonsai seedlings and trees during late winter season. This means that the time period from end February to March is optimal. This is because during winter Bonsai is in a dormant condition and will not be as shocked when replanted.
When the Bonsai seedlings and trees are growing actively, repotting can prove to be quite stressful. Therefore, pruning and transplanting should be done before the start of the growing season.
When we cut roots during repotting Bonsai, they start to repair themselves immediately. If you prune roots and repot your Bonsai during growth season, the plant will not find time to heal. It will remain open, and become prone to a serious pest and disease attack.
How often should you repot Bonsai?
There are two main factors that will help you decide on how often to repot Bonsai seedlings and trees. These include the following:
- Size of the pot
- Species of the Bonsai tree
Bonsai tree species that grow faster need repotting around every two years. Trees that are mature need repotting every 4-5 years, because they are established and grow more slowly.
Repotting Bonsai seedlings and trees is not a routine task. You only need to check your Bonsai at the start of the spring season.
Try to take the tree out of the pot and examine the roots. If they are circled around the rootball, then repot the tree right then. If this is not the case, and roots are still in the soil, then leave it like this, and check in the following spring.
What soil to use for repotting Bonsai?
You have to choose a suitable soil mixture for repotting the Bonsai. This way you will make sure that your tree can thrive in your location and environment.
Soil mixture to use when repotting Bonsai will depend on the species of your tree. For deciduous trees, it should contain 2:1:1 of Akadama, pumice, and lava rock. But for conifers and pine, you can use 1:1:1 of Akadama, pumice and lava rock.
The soil mixture must allow proper drainage of water. This is to ensure that the roots don’t rot, due to standing water and salt buildup over time.
If you think that watering Bonsai regularly would be hard for you, try to add more Akadama (clay particles). Akadama will allow more water absorption and prevent the Bonsai from dehydration. Make sure to sift before use. If the climate in which Bonsai is growing is humid, then add a bit more lava rock. It will improve drainage in the pot.
Can I use normal potting soil for Bonsai?
You cannot use normal potting soil for Bonsai, but you can surely use it in a potting mix. Normal potting soil doesn’t provide good drainage and aeration, and doesn’t provide essential nutrients and gas-exchange required for Bonsai to thrive.
Normal potting soil can be added in small quantities if you want to improve texture, and add water retention qualities to your potting mix. That would be more suitable for hot climates. However, don’t use the potting mix on its own for growing Bonsai.
Tools for Bonsai repotting
Before you start repotting your Bonsai, there are a few things that you will need to prepare. Those include:
- A suitable pot that is few inches bigger than the previous one.
- Bonsai soil – you can buy a ready mix or make it yourself. You can experiment a little.
- A few tools for pruning and transplanting the Bonsai seedlings and trees, such as scissors, a brush, wire cutter, tweezers and more like this.
- To cover the holes of new pots, keep mesh like this handy during the Bonsai re-potting.
- The insecticide (natural ones include neem oil or insecticidal soap, for example) in case you notice pests in the soil
Keep extra Bonsai soil mixture so that you can add when some of the soil washes away after watering. Try to use the same mixture that was previously added to the Bonsai pot.
Choose the right season to repot your Bonsai
Ideally, you should do the Bonsai tree repotting in the early spring. This is mainly because Bonsai trees are not yet in full growth, and just coming out of dormancy. Therefore, the shock effect of repotting will be reduced.
How to Repot Bonsai Seedlings and Trees – Step by Step
Here are few simple steps that you need to follow in the process of repotting your Bonsai.
Step 1. Prepare the tools for repotting
As mentioned above, you will need some tools to successfully repot your Bonsai. Make sure to prepare root scissors/shears, rake, wire cutter, tweezers and other tools. If you don’t have all the tools, you can get a full set of tools like this.
If you are repotting a seedling Bonsai, you won’t need much to take it out of the pot. Roots will also be thin, so be careful not to damage them. Most horticulturists use peat pods for seeds, so you will just need to break it open and take your seedling out of it.
Step 2. Cut the wire
Before you repot your Bonsai tree, you will need to cut the old wire that was holding your Bonsai to the pot. Use a wire cutter for this purpose. After that, remove your Bonsai carefully using your finger to work through the soil and a rake/hook. Usually, bigger and older trees are fixed wire wires that are pushed through drainage holes from the bottom to top. This helps hold a tree in place.
If you are repotting a seedling Bonsai, there’s not going to be a wire holding it down. You will just need to take it out of the pot and place it into a bigger pot.
Step 3. Take out the Bonsai from the pot and examine the roots
First of all, you will need to take out your Bonsai from the pot. If it’s a seedling in a degradable pot, you can just break it. If it’s a young tree, you can often easily take it out of the pot. But if it’s an older tree, you might need to use a root saw or another similar tool. Use the tool to separate your Bonsai from the pot. Separate the root ball from the pot walls, but do not cut into the actual rootball.
Then, examine Bonsai tree roots. Make sure the soil is dry before you start checking and repotting. Are roots circled around the rootball and the pot? Are they coming out of the pot?
If yes, then it shows that they lack enough space to spread out, and Bonsai needs repotting. Roots grow the shape of the pot, and nutrients get used up in the soil, so repotting is crucial.
Check the roots and make sure there are no small bugs. Root aphids, for example, are small white bugs that suck sap from roots. If you notice root aphids or other pests, use some insecticide like this to get rid of them.
Step 4. Remove Old Soil
Once you start repotting your Bonsai, you need to remove old soil from the roots. You can use your fingers to begin with. This way you can remove all the dried soil, but it’s also likely to fall away (make sure soil is dry).
Use a root rake or claw like this to make this step easier for you. Additionally, it will help in de-tangling Bonsai roots if they are grown thickly together. Start de-tangling roots by using the rake using careful motions from inside to the outside of the rootball. Move outwards only, and use a chopstick for fragile roots.
Keep some of the old soil, as it contains beneficial microorganisms. You can add some of it to your fresh soil.
Step 5. Prune the roots
Pruning some of the old roots will help your Bonsai grow better. It will also provide more space for your Bonsai to grow and will encourage it to grow new finer roots, and thus – new branches and twigs. It will also prevent the tree from being root-bound, when it can no longer access water and air. When removing old soil, you will notice fresh roots growing from old, thick roots. Cut old thick roots with disinfected scissors or shears. Moreover, make sure that you cut any rotten or dead, brown roots.
Be careful with how many roots you cut off, because it can be deadly for a Bonsai. Do not prune more than 20-30% of the roots. Cutting too many roots can kill an otherwise healthy Bonsai in just a few days. It will prevent it from absorbing water and nutrients properly.
Use a forked tool, such as a rake, to remove old soil gently. For seedlings with finer roots, use a chopstick. Avoid damaging roots, as this will damage the whole tree. Cut old roots and trim many fibrous roots that are gathered together and are too long.
There’s no need to cut off too many roots, as you can do it with the next repotting. It’s much more important to prune old thick roots to help with fresh growth, but don’t go overboard. Also, cut off any discolored or dying leaves, remove debris. You can use a bonsai brush for this purpose.
Step 6. Prepare a new pot and wire it
Prepare a new pot that you will repot your Bonsai into. You should do this before taking your Bonsai out of its old pot. Once you have a new pot, you will need to wire it (use aluminum wire). Make sure it has drainage holes on the bottom. Take small pieces of plastic mesh (can cut to size) and cover your pot’s drainage holes with them. To fix it on a pot, take a wire, and bend it into a U or a π shape (you can use pliers). Then, pass the wire from inside the pot outwards, through the drainage hole.
You will then need to pass two long wires from the bottom of the pot through the drainage holes (towards the inside of the pot). These wires will hold the Bonsai in the pot. You will bend them once the Bonsai is in the pot and push them down on the soil. That is very important because wiring before will help your Bonsai roots adjust and balance properly and won’t put strain on the whole tree.
Step 7. Repot your Bonsai
As the root trimming and leaf pruning are done, put the Bonsai tree into a pot. You may add a new soil mixture before doing this. Try to pack the new soil with the roots of the Bonsai tree to avoid air spaces between them. Make sure that all roots are covered with soil. Level the soil and don’t compact the soil.
Step 8: Water your Bonsai
Watering is the last, but yet crucial step in the Bonsai tree repotting process. It will help in settling the new soil with the plant roots. Other than this, it will also protect the newly transplanted Bonsai tree from extreme winds.
Be careful not to overwater your Bonsai, because you have just removed lots of roots. Water lightly, because you will need to place your Bonsai in a partial shade after repotting.
Freshly repotted Bonsai tend to go into stress or even a shock mode. For this reason, you will need to keep your Bonsai in comfortable conditions at around 20 C (68 F) for around a few weeks. Don’t move your Bonsai around either, as most react negatively to this. Don’t fertilize for a month either.
Tips on Repotting Bonsai Seedlings and Trees
Below are a few tips that you can follow during the repotting process Bonsai seedlings and trees:
- Always do the Bonsai re-potting away from the sunlight. Exposure to the sun will dry out the roots.
- Active roots are small and white, so trim all the long and thick ones instead.
- After pruning is done, put some soil mixture and mulch on the top of the gravel layer.
- Spread the roots in the pot when you are putting the Bonsai tree back into the pot.
- Remember to put the plant in the right direction and the center.
- Press the soil mixture to remove the spaces between the soil and root.
- To moisten the soil optimally, leave the pot in a pan of water for half an hour.
How to repot Bonsai seedlings?
Bonsai seedlings are much more fragile and need a careful approach to repotting. If you are growing Bonsai from seeds, it’s a good idea to pot at least 10 seeds, but even as many as 50-100. That’s because many are likely to die before getting big and strong. Please remember, that different species of trees require different stratification processes, soil and other conditions to grow, so avoid mixing them in one pot.
To make sure your seedling thrives and becomes strong, you need to prune its roots around 10-12 months after germination. Root pruning will allow you to create a compact root system that is important for Bonsai growing. When repotting your Bonsai, always check for roots, and prune a taproot (dominant, thick root) that has formed. You should be aiming at leaving finer fibrous roots and encourage their growth. Make sure to cut the taproot with a clean and sharp tool.
Repot your small Bonsai seedlings into small pots. Use specifically designed Bonsai soil that will provide aeration and good drainage (lava, pumice, Akadama etc). Once you see your Bonsai seedling grow, you can expose it to more sunlight (shelter from direct light for some time in the beginning).
Bonsai repotting aftercare
Keep the following things in mind for the aftercare of Bonsai seedlings and trees, so that they may thrive and flourish. The list includes three main points that you need to focus on, to maintain the Bonsai tree after repotting.
If you believe your Bonsai is dying after repotting, please see this post for further help.
Soil condition
Aftercare of the Bonsai plant requires you to maintain the pH of the soil in which it is growing. While it’s not a very crucial thing to think about, checking and controlling it can greatly help with Bonsai care.
pH levels can be important because various minerals are available to the plant at different levels. That’s because their solubility levels are determined by pH levels of the soil.
For this, you can use a simple soil pH meter like this. It should be between 6.5 to 7 pH. It is slightly acidic to a neutral pH range at which all soil nutrients are easily available for plant uptake.
Lighting
Just after repotting, limit sunlight exposure for your Bonsai for 3-4 weeks. That’s because newly repotted Bonsai are sensitive, and very bright light will shock them. Please note, that your Bonsai might lose leaves after repotting, and it’s often normal.
Most of the Bonsai plants require around 6 hours of daily sunlight to thrive properly. However, this can be different depending on the species of the tree.
Watering
Put your finger an inch into the soil and check if it feels dry or not. If it is dry, then know that the Bonsai plant needs watering. You can also check the 3 in 1 pH meter mentioned above which will tell you if soil needs watering.
Add a little bit of water to moisten the fresh soil. However, never allow the soil mixture to get flooded with water because that will rot the roots. Be careful in the beginning. You can also mist your Bonsai for the few weeks after repotting.
The watering schedule should be set considering the season of the year. In the summer season, you need to water it daily. However, in the winter season, you can do it twice a week only. It is a very important aftercare step that you have to follow to maintain the plant.
Thank you for reading this post on repotting Bonsai seedlings and trees! To learn more about Bonsai care, please see this page.