For most varieties of bonsai, there are many approaches to repotting. Soil mixes, timing, and the number and selection of roots to be cut can vary widely depending on who is doing the work.
When it comes to azaleas, this isn’t the case.
Satsuki bonsai care – at least the basics – is fairly conventionalized. The planting medium is kanuma. The top dressing is “mountain moss,” and the repotting time is early spring.
Here’s what the process looks like for trees that have been bare-rooted.
Satsuki azalea – ‘Koyo’
Azaleas exported from Japan are frequently cut back, bare-rooted, and wrapped in New Zealand sphagnum moss to keep the roots from drying out.
Roots wrapped in moss
During the bare-rooting process, many roots are often cut to ensure there are no soil particles left behind. The result can be a surprisingly small root ball.
It’s common for these rootballs to be a mix of structural roots and fine roots.
Rootball with big and little roots as seen from below
The basic approach to repotting is the same for azaleas as it is for other varieties. The primary difference is that the most common soil mix is 100% kanuma, a volcanic medium mined 3 meters below the surface in parts of Japan.
After repotting in kanuma
Kanuma is primarily composed of silicic acid (51%), alumina (16%), and iron oxide (9.9%). The kanuma used for growing azaleas is often hidden from sight, however, as it is frequently covered with mountain moss.
After covering the surface of the soil with mountain moss
Mountain moss helps preserve moisture in the pot – a valuable capability considering that azaleas can suffer significant damage when the roots dry out, even if for a short time.
And that’s the basic approach to repotting satsuki bonsai. If you live in a country that imports bare-root azaleas from Japan, it’s likely that your tree went through a similar process at some point.
Next up: what to do when there are deep pockets in the rootball.
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