This Ficus microcarpa was potted into a 24″ round ceramic pot in 2015. By 2018, it needed repotting again but I procrastinated and did not do it in 2019 either. I finally repotted it a few days ago, but into a wooden box. I jokingly said it was because I needed to reduce the overall weight. That is true but there are more important horticultural reasons repotting it into a wooden box, like rejuvenating the roots, regaining the tree’s health, and working on the overgrown aerial roots and nebari.
Why Use a Wooden Box?
To restore a bonsai’s health, it is a good idea to repot the tree into a slightly larger container, preferably in a terra cotta pot, a wooden box or a Styrofoam box. A slightly larger container provides more soil volume and extra rooms for the roots to rejuvenate, increased surface areas between soil aggregates also allow the roots to breath better and grow more fibrous roots. A cedar picket fence wooden box is an obvious choice since I cannot find a larger terra cotta pot or a big Styrofoam box. Although the latter can protect the roots from over heating during our intense summer heat, it is too glaring and stands out too much among the other trees, unless I could paint it.
As for weight, the 24″ ceramic pot weighed 32 lb., a comparable wooden box weighed about 5 lb. I made a rough calculation, this round pot with tapered wall has a volume of about 1,100 cubic inches (about 18 L.), a square box holds almost twice the amount of soil. Your tree will thank you for the extra room while in recovery.
Reworking Overgrown or Thickened roots
Aerial roots are great for improving the tree’s nebari, but they can become too big, crisscrossed or grew in unintended direction if one is not diligent in controlling and incorporating them to the intended design.
These two photos show how the skinny grafted aerial roots grew in 4 years without repotting in between:
These grafted roots needed repositioning and incorporating into the nebari:
Exposing More of the Nebari
Every time I repotted, I raised and exposed the nebari by about 1/2”. This time I raised it by about an inch. Exposing it gave the tree a larger nebari in each repot.
Another advantage of using a wooden box is I could easily put in a few screws on the box to attach guy wires to bring down branches.