Repotting our trees is a key bonsai practice, and one that you must gain mastery of. Here is a summary of basic steps you’ll take each time you repot your trees:
- Make sure you have all necessary tools and supplies, including prepared soil, before you start
- Have a suitable space to work in – outdoors a bench is ideal, indoors a small bench or table and a large tub to work in will help keep the mess contained
- Prepare the new pot if you’re changing pots; if not, you’ll need to thoroughly clean the existing pot, replace drainage screen and the tiedown(s)
- Unpot the tree and inspect the root mass
- Comb out the roots which will have coiled their way around the outer edges of the mass
- Trim away the overlong roots and enough of the root mass to give room for fresh roots to grow
- Make needed corrections to the roots, namely the exposed nebari roots that are part of your design
- Add fresh soil to the pot to provide a thin bottom layer – slightly heaped in the middle
- Place the tree in the pot
- Tie the tree down once you’re satisfied with the placement
- Fill in all around the tree and any spaces in the root mass; use a chopstick or other tool to work the soil in
- Water thoroughly; allow to drain; water thoroughly a second time; newly potted or repotted trees with fresh soil will need to be watered more frequently than others, as it take a while for the fresh soil to become properly wetted
- Fertilize (this is optional at this time, but I tend to forget as I move on to other trees, so I go ahead and do it at the time of repotting)
- Place moss on the surface if so desired.
This is today’s subject, the Chinese elm that has its own Progression page.It was last repotted in 2018, and though it could probably go another year without it, there are a couple of issues with the nebari that I want to correct before they get out of hand.
This is one of the roots that I’m unhappy with. Though it’s grown well and is about healed from the previous pruning I did, it’s just too straight and untapering a surface root to remain. I can solve this problem as part of the repotting process.
I combed out the root mass, trimmed away some of the excess roots, and washed off the excess soil that I’ll be replacing. It’s easier to see root problems once you get to this stage. In this case, it’s a root that’s coiling back toward the trunk base. These should either be removed entirely, or if you need a root that’s grown this way then gently uncoil and trim it so it grows in the desired direction.
Here’s the tree after the final root trim. I’ve removed about a third of the total root mass, which is the right amount for this repotting. The amount of root mass you remove will vary based on how long it’s been since the last repotting, and how much root the tree has grown in the interim. With experience you’ll be able to immediately gauge this as soon as you pull the tree from the pot.
Here I’ve placed the tree back in its pot. I previously washed the pot thoroughly, made sure the drain screens were in good shape, and replaced the tiedown wire.
Placing your tree in its bonsai pot requires you to consider several parameters to ensure the composition is its best. They are (in no particular order):
- Determine the correct placement of the trunk base – in this case, since my tree emerges straight from the soil and terminates left of center at the apex, the base needs to sit slightly toward the right side of the (oval) pot
- The tree also needs to sit slightly to the rear of the pot
- The tree sits on a slightly heaped mound of soil, which brings the base just above the rim of the pot
- I had previously selected this pot because it is, in profile, roughly as deep as the trunk base is wide
- The pot measures about one-half the height of the tree in length, making for a good proportion
- The initial portion of the trunk emerges straight from the soil; the planting angle needs to be such that the initial portion of the trunk is perpendicular to the pot rim.
The final presentation for today. I did a little trimming of the branches (there’s probably a little more to be done), then watered and placed some moss on the surface. I also added some time-release fertilizer so I don’t get busy with other trees and forget. Because I’ve done root work on this tree today, it’s probably going to start opening buds within the next week. I have a lot of small Chinese elms in gallon pots, and most of them area already leafing out. Spring is getting closer by the day!
Let me know what you think of this repotting job.