In this instructional video, the presenter demonstrates a technique for repotting coniferous bonsai—specifically Alberta spruce—without fully removing the tree from its container. He explains why keeping the exterior root ball intact preserves existing fine roots, and he uses a wooden implement to carefully excavate the interior, removing compacted, wet, air‑less organic soil. The removed soil is replaced with a granular inorganic mix of lava, pumice, and akadama, often topped with larger‑grained pumice to improve aeration and moisture regulation. The video outlines the ideal timing (late summer to early autumn), the gradual nature of soil transition over several repottings, and the expected benefits: stronger shoot extension, healthier root growth, and reduced risk of die‑back when future styling is attempted. The method is presented as applicable to other conifers such as juniper, pine, and cedar. The presenter also notes practical considerations like avoiding metal hooks, managing nebari roots, and placing the repotted trees in a cool, partially shaded garden area. The video concludes with a call to like and subscribe.
Chapters
It isn't always necessary to remove a bonsai from its container when repotting, and this video shows circumstances where it's actually advantageous. Both of these examples are again with spruce. I seem to have quite a few of them as raw material at the moment, but the technique can be equally applied to juniper, pine, cedar, and other coniferous species. This Alberta spruce was collected from a garden a few years ago And when I purchased it, it was sitting in heavy clay ground soil. A year ago, I planted it into a slightly larger container and backfilled with an inorganic mix of lava, pumice, and akadama to give the tree something healthier to root into. At the time, I couldn't remove the ground soil as that would have been enough to have killed this fairly weak tree at the stage it was at. It's better to slowly change the soil of coniferous species over 2 to 3 repottings anyway. As my previous videos have discussed, the end of summer and early autumn is when I do the repotting of most of my coniferous species, and it is very safe despite the day temperatures still being relatively high. The exterior of the root ball is left alone so that new roots are left undisturbed. Instead, I carefully clear out the interior of the root ball with a wooden implement to avoid the damage that metal root hooks cause. The soil is so poor in this area that there are very few fine roots, if any, just the thicker roots that connect to fine roots at the base of the pot. The soil in the interior is wet, airless, and even cold to touch. a poor environment that will not encourage a healthy root ball and therefore a healthy bonsai. The ground soil is carefully removed. My objective is not to remove every last bit of the ground soil, but to remove enough that I can then introduce a warmer granular soil mix that will bring aeration to the center of the root ball. This technique always brings good results during the following year. Top growth is stronger and has better extensions, a sure sign that the new growth— root growth is equally strong and has vitality. I backfill with some larger-grained pumice to really open up the soil, followed by a standard lava, pumice, and akadama mix. You can see the pile of ground soil that I've removed from the root ball, and I'm really glad to see that it's gone. The tree will wait another year before styling. I could design something with the foliage I have already, but while the foliage on the tree is not vigorous, there is a chance of dieback setting in after styling. It's not worth putting the tree back in its development by trying to push it forwards too quickly. This second spruce, another Alberta spruce, was purchased last September in poor health with plenty of new buds at the tips of the shoots but also a lot of dieback. I did the exterior of the root ball of this one as well before planting it into a slightly larger container. The results were much better extension and health this year, but I still wanted to ensure that the center of the root ball was checked over a new soil introduced. It's a big tree, certainly bigger than most of the spruce material I see here in the UK, and I'm excited about styling this one in the future. The soil here is better than the previous example but still consists of a lot of peat and sand mixed together. A mix of lava, pumice, and akadama and an inorganic soil mix will bring much better health and vigor over the coming years. Fortunately, the tree has a lot more healthy fine roots in the interior, so I am much more careful when working around them, and a much smaller volume of old organic soil is removed. This work also allows me to address some of the roots creating the nebari. These are pinned out of the way with a view to making further rearrangements in future years. The excavated area of the root ball is filled with pure pumice on this occasion. Any good quality inorganic soil mix would work, but pumice will be drier in what is a large container that could take a long while to dry out between waterings. I then add a shallow layer of akadama to allow for better indication of when the tree needs watering in the future. Next year I hope to give the tree its first styling if there is enough elongation of the new shoots. Given the distribution of the primary branches, a traditional branch structure with branches carefully emerging from the left, right, and back of the trunk won't be possible, but I can see a naturalistic huge mountain-style old spruce in there. Both trees are returned to an area of the garden that is partially shaded Cooler and humid, the perfect environment for all spruce bonsai. If you enjoyed this video, please like and subscribe.
