The act of repotting is often misunderstood. Some people think it is unnatural or unkind, however, in reality, repotting and pruning is not only safe, but it is vital to the health of your bonsai. It may seen counter-intuitive, but your bonsai will grow faster afterwards.
The roots of your bonsai are what sustains it, their purpose is to connect with the soil and carry the water into the plant. They do this using the several fine root hairs that grow daily.
Why Repot Your Bonsai?
As time passes, a tree growing in the wild will spread its roots out to find adequate moisture and continue its growth. Confined to a small pot, bonsai are unable to do this and so the roots begin to circle around the root system ultimately causing suffocation.
How Often Should You Repot Your Bonsai?
There is no set rule as to how often you should repot your bonsai and you should not repot on a schedule. Factors such as species and pot size will affect how often you want to repot your bonsai, there are some bonsai trees which will require repotting every year or at least every two years. This is the case for most young bonsai. Some more mature trees might only need repotting every 3 to 5 years. You should however check your bonsai yearly to see if it requires repotting. You can do this by lifting it gently out of the pot and checking the roots. If the roots are growing round the root system, then it is time to repot.
There are some signs which could suggest your bonsai may need repotting, these include slow growth during the previous season, reduced leaf size, yellowing of leaves, the root bulb slowly rising in the pot and the shedding of the leaves in the very early autumn. Also, if the soil is dry and compact it could be time to repot.
When Should You Repot your Bonsai?
Again this depends on the species of the tree. Generally, you should repot your bonsai in early spring whilst it is still somewhat dormant, at this point the roots are having to sustain less foliage and will hopefully recover quickly so that they will be fully healed and able to sustain a healthy growth phase over the summer. Tropical bonsai can be repotted at any time of the year although early spring is the preference, if your bonsai is showing signs that it might require repotting at any point in the year then you should go ahead and check it. Repot if needed.
What Will I Need to Repot My Bonsai?
You will need a suitable pot, mesh to cover the drainage holes, wire, a carefully chosen soil substrate, a root hook, root rake, chopstick or bamboo stick and a container of water for when you’re done.
It is helpful to reduce watering for a couple of days before you repot. Working with wet soil is difficult and of course messy too. Dry soil will make the process a little easier!
If you are repotting outdoors, stay in the shade as roots exposed to the sun will dry out in a short amount of time.
8 Steps to Safely Repot Your Bonsai
You can use the below instructions to report most any bonsai plant. If you need more information on soil selection check out our Ultimate Soil Guide.
Step 1: Remove Your Bonsai
Remove your bonsai tree gently from the pot. Turn the pot upside down and tap the bottom. You don’t want to tug too hard on the tree incase you damage it. To make this easy, I loosen the soil around the edges a little first.
Step 2: Prepare Your Pot
Prepare the pot by placing the mesh over the drainage holes. Put the wires in place so they are ready to anchor your bonsai tree. It is not always necessary to repot into a larger container, so consider the age and size of you bonsai tree and also the size you aspire it to be in the future.
You may want to think ahead and have a new pot ready. Some bonsai artists choose to create their own pottery as part of the art form. If you’d like to learn more about pottery, check out SpinningPots.com.
Step 3: Clean the roots
Using a chopstick or a root hook, clean the soil from around the roots, take care not to damage the roots. Do not remove all the soil, a little drop of the old soil is good for the bonsai.
Step 4: Prune the roots
Prune the roots where necessary. If they have grown excessively long it is important to prune them, you should not remove more than 40% of the roots. Try to avoid new roots or those with fine white hairs. If it’s the first time you are repotting it is better to err on the side of caution and prune less, you can always do more the next time. Junipers and pines will be more tolerable of pruning than other species.
Step 5: Lay the substrate
Place a small layer of your chosen soil substrate in the bottom of the pot and sit your bonsai in it. Make sure to use your wire to steady the bonsai. Do this by running it around some of the larger roots. Most enthusiasts choose to place their bonsai slightly off center for aesthetic purpose.
Step 6: Add the soil
Fill the pot slowly with soil, use a chopstick or your fingers to gently push the soil around the roots. This should be done with care; you do not want to damage the roots. Using a circular motion to push the soil down is an effective method for this process. Try not to leave any holes.
Step 7: Secure the wire
Twist the wire around to ensure the bonsai is stable and not going to shift in the soil. If your bonsai is not stable it will not heal and recover as quickly.
Step 8: Water the bonsai
Watering is very important for your tree’s recovery. So do not forget this step. Make sure that you give it enough water so that you can see it coming through the drainage holes at the bottom of the pot. Many enthusiasts use the immersion method at this point. You can check out our Bonsai Watering Guide for more information on this step.
It is not advisable to feed your bonsai tree fertilizer for the first four weeks, following repotting.