There are a few small trees which I over-potted in hopes of them growing more vigorously. But a small tree in a big colander often left the medium too wet, and as a result, the tree suffers. Today, I repotted two trees into a smaller colander. My hope is that the reduced amount of soil would allow the medium to dry more quickly, and as a result, promote the tree to put out more roots.
I first started with the Japanese Maple. I originally potted the tree very low in the colander, forcing the roots to go radially rather than downwards. This plan worked well, as the tree has a very radial and flat nebari. I simply trimmed some roots off the rim, painstakingly rearranged the roots so that there are no overlaps, and then potted it into a smaller colander.
The second tree is the Boxwood. Boxwood are very slow growing trees, especially so when grown inside a pot. For the past two years, the tree remains largely the same size. Some nice roots have developed. Similar to the Japanese Maple above, I arranged the roots nicely, before potting it into its new (much smaller) colander.