After wiring a bonsai into the pot and filling the pot with soil, I’ll usually give the whole a few gentle taps to make sure I did a good job with the chopsticks. A few gentle taps can quickly reveal faulty chopstick work as the soil will quickly settle in neglected areas. I usually tap at least two sides of the pot while securing the base of the tree with my other hand.
Tap a little bit too hard and the soil can pop out of place leaving the tree loosely secured and requiring starting the process all over again.
For the last step, I tamp the soil into place with my hand. Many wonderful and miniature trowels are made for the purpose, but hands can work well too.
Tamping the soil
Is this last bit necessary? Good question. I’ve noticed that when I water after repotting, the soil tends not to move around as much after tamping the soil like this, and for this reason alone I continue to do it.
Some of the final steps when repotting bonsai are among the most important – especially when it comes to wiring trees into the pot. I typically wire trees into the pot after setting the tree, but when repotting partially or completely bare-rooted trees, I first work some soil into the exposed roots. If no soil is around to hold these roots in place, tightening wires can scrunch roots together, collapsing the rootball and making it difficult to secure the tree firmly in the pot. As I bare-rooted about a third of the roots of the tsukumo cypress below, I filled in the areas between the open roots and around the rootball before starting with the wire.
After adding enough soil to facilitate wiring the tree into the pot
There are several approaches to wiring bonsai into pots, each with their good points depending upon the application. For this tree, I used my default approach for posts with four holes. Taking hold of the front left wire, I brought it to the point where the front right wire emerged from the soil.
Bringing the wire across the front of the rootball
Where the wires meet I twist them together by hand. If I want to make sure the wire is particularly snug at this point, I use pliers.
Grabbing the wire with pliers
If there is a single take-away from this post, let it be this: pull, then twist. If you have ever repotted bonsai with Boon Manakitivipart, you’ve doubtless heard this phrase. The idea is that when tightening wires, first pull the wires tight, then slightly release the tension while twisting. Simply twisting soft wire like aluminum is an easy way to break it. The alternative: pull, then twist.
1. Pull wires away from rootball
2. Lower pliers while twisting
The pull, then twist, approach may be repeated until the wire is snug. After securing the first three wires, you may notice you have nowhere to attach the final wire.
Where does this one go?
Sometimes I plan ahead by preparing a short section of wire with a loop that I can fit around the first wire.
Short wire with loop
As I didn’t prepare this bit ahead of time, I can do it after the fact with a short, hooked section of wire.
I hook this wire under the base of the first wire and then twist it back onto itself.
Hooking the base of the first wire
After securing the wire with a twist
Adding this tail let’s me connect the first wire with the final wire. For this final connection, I always use pliers to ensure the tree is well-secured to the pot.
The last connection
Tightening this last connection ensures the wire is tight across the entire rootball. Once the wire is snug, I remove any excess strands and fill the rest of the pot with soil.
After adding the soil
Two more quick steps – more on that Friday – and then it’s time to water.
When repotting bonsai, I try to keep roots exposed to air for as little time as possible. When I know what pot a tree will be planted in ahead of time, I’ll add wire and screen to the pot before I begin the rootwork. I knew I’d plant my sawara cypress into a terra cotta pot ahead of time so I began the process by adding screen and wire (2mm aluminum) to the pot.
When I was finished with the rootwork, I started adding soil to the pot. I began with a drainage layer of pure pumice.
Pumice drainage layer
I then added some bonsai soil, creating a small mound on which I placed the rootball.
Bonsai soil in the bottom of the pot
Next comes the tricky process of setting the tree. Mound up too much soil and the surface roots will be exposed to the air. Mound up too little and the base of the trunk gets buried. Once the soil level is correct, I nestle the tree into place with a gentle twisting action. After the twisting, the tree should come to rest at the idea height, centered equidistant from all edges of the pot, and set at the proper planting angle.
This often requires more than one pass. If, after nestling the tree into the soil, the base of the trunk is too low, I remove the tree, add more soil, and repeat the process until I get the level right. I never mind taking my time with this stage as it’s far easier to correct mistakes here than it is once the tree is planted.
Boon gently twisting a dwarf sawara cypress into the pot
Checking the planted angle
Making further adjustments
Once again checking the level
When planted at the appropriate level, I can fill the pot with enough soil to just cover the surface roots without filling the pot to the rim.
Tree set at the proper level
After adding bonsai soil
What about wiring the tree into the pot? Details next week.
When repotting coniferous bonsai growing in nursery soil – typically soil with a lot of organic material – I try to remove all of the soil from a portion of the rootball. How much old soil I remove or bare-root depends on how many roots I find and the overall health of the tree. In the case of the Tsukumo cypress I’m working on, I decided to bare-root about one third of the old soil after reducing the rootball.
Sawara cypress – all of the soil has been removed from almost one third of the rootball
After working on the sides of the rootball, I turned the tree on its side and worked on the bottom.
The bottom of the rootball
I began by combing out the roots with a small rake.
After combing out the roots
I then trimmed the exposed roots, being careful not to place the scissors next to the rootball when I cut. By leaving maybe 1/8″ – 1/4″ of the roots exposed, the roots can nestle themselves into the new soil. As bonsai soil drains much better than nursery soil, new roots will have less trouble sending out new growth.
After trimming the roots
At this point the tree is ready for repotting.
Ready for repotting
I followed a similar procedure for the dwarf sawara cypress below. Here is the tree right before it was planted in a new pot.
Dwarf sawara cypress ready for repotting – details Friday