This one was a touch my fault. I bought a small Japanese Boxwood from a big box store two months ago. I did see a touch of roots at the bottom of the pot but life happened and I didn’t get a chance to repot it for a while. I chopped off the top and figured I’d repot later. With only a touch of roots at the bottom it didn’t seem like an emergency and I made the mistake of not sliding it out of its pot to really see what was going on.
This weekend I sat down with it and found it the most root-bound plant I’ve seen in a long time. This thing was a mess.
Roots had grown across the bottom, tying it into its plastic store pot. When I did get it out of the pot, inside I found a pot shaped root mass. Calling what I had a root ball is a misnomer. There was nothing ball like about this, it was a perfectly compressed cylinder.
With a sharp pair of scissors I cut a slice off the bottom of the roots. (You want your cutting instrument sharp so you cleanly cut, not mash them off. A saw might work just as well. To each their own.) With a solid root mass like this, cutting the bit off the end reminds me of cutting the end off of a loaf of bread. It was tough to dig into, and tough to do precisely.
Then I started working the roots out. We break up the root ball because those internal roots can’t get any fresh soil or nutrients, when they’re bound up. It also helps the plant in question start the journey to become a bonsai tree. To be trained for a wide shallow pot, we need to start changing the shape of the roots just as we change the shape of the branches. It also helps you pick out the woody roots and feeder roots, and start working the roots into a horizontal rather than vertical direction.
There was very little soil left for this poor tree. Any remaining soil was found in pea sized hard balls mostly deep inside the root ball. Maybe 2/3 of the volume of the pot was roots. After combing it out there were only two or three larger roots, and a couple of those had to be cut back. The longest roots were trimmed.
Between sawing off the bottom and all the roots lost in combing out the root ball, I must have gotten rid of perhaps 2/3 of the root mass. I spread out the remaining roots, aiming for flat and round, and repotted in a pot more wide and shallow than narrow and deep (I’d normally go for a bulb pan but I got some cheap small plastic hanging planter pots at the dollar store that do the same job). I repotted with potting soil.
Potting soil certainly isn’t the ideal medium, and having something better draining with a tree I’ve just given such a beating to would definitely be helpful. But the discussion of when a tree begins being “in training” or “pre-bonsai” and how important it is to pot pre-bonsai in bonsai soil, and what over factors are in play involves some personal choices and preference I’ll happily discuss somewhere else.
Because it took me so long to write the story up I have another post. The tree is doing fine and showing new growth after two weeks. I’ll stick a tag in it and restyle it next year.
WHEN TO USE WHAT TOOL FOR ROOT PRUNING A PRE-BONSAI
This boxwood is a good example of distinguishing when you’d want to use your hands, a root hook, root rake, and a chopstick in repotting. Understand though that this isn’t always the case. Perhaps even most of the time you can break up the root ball of nursery plants by hand. Also if you were working on large or small bonsai these would not be true. Overall, use whatever tool seems necessary and appropriate for the tree you are working on at the time.
By hand all I managed to do was dust off most of the dirt on the outside of the root ball. Even taking two hands and grabbing each side of the cylinder and pulling didn’t get me anywhere.
The root hook is ideal to split up the mass of a root bound pre-bonsai this way. You can sneak deeper in and pull the mass into sections. There’s the advantage of the hook being made of steel while a chopstick made of wood may break before the job is done, but the advantage is really in the hook itself. It has to be a hook instead of the rake to keep it strong and the force focused on one point. If you had an entire soccer ball sized mass of tangled hair to break down and neaten up would you start by digging a comb into it?
The root rake is better for the next step: combing roots out. Once you’ve broken the mass into sections, teasing out all the fine feeder roots that are enmeshed up under the root ball would take considerably longer to do by hand. Just like a comb for your hair, there simply isn’t much of a substitute for what it does. It’s the right tool for the job. Think of your new handful of tangled hair. Are you going to comb that flat out with a chopstick or metal hook?
A chopstick is perfect for after you’ve untangled and pruned your roots and are now repotting your pre-bonsai. The chopstick can help you situate new soil mix particles in around the roots. I don’t have an analogy for this one; it’s just the right one for the job.