Kathy Shaner – Repotting Your Bonsai

On January 23, 2018, we conducted our first meeting and demonstration of the new year, featuring club sensei Kathy Shaner. Kathy arranged for an exciting and fun hands-on repotting workshop, where four club members were given the opportunity to repot their own bonsai under her guidance and instruction. Kathy approached the demonstration like her advanced workshops, moving from one club member to the next, giving her expert instruction to each and ensuring the proper steps were taken.

Repotting bonsai at regular intervals is critical to the health of your bonsai. Each step taken ensures the repotting is done correctly. In general, you determine if the bonsai requires repotting. By examining the roots, you can assess whether the roots are circling themselves which will eventually grow thick enough to displace the soil and water causing the tree to starve and die. The usual season for repotting in Northern California is December through March. This is the time for less activity and growth and the bonsai is impacted by less shock. Some bonsai, for example the tropical ficus, like early spring. Remove the old soil. Deciduous can be bare rooted. However, never bare root a conifer all at once. Comb the surface roots using a chopstick, root hook or rack to radiate from the trunk. Gently disentangle the roots if they have grown thick and in to each other. Remove some of the bonsai’s roots. Remove long roots and downward growing roots. Use a sharp root scissors and cut away any damaged or dead roots. After cutting away the proper portion of roots, position the bonsai in its pot. There should be a layer of soil mix in the bottom of the pot. A common bonsai soil mix contains Akadama from Japan, lava rock and pumice. Ensure the pot holes have been covered with plastic screens and have tie down wires BEFORE placing any soil mix in the pot. Work the soil mix gently around the bonsai roots and make sure the trunk and roots are secured with tie down wires. Add additional soil mix and work it in to be sure to eliminate any air pockets. Water the repotted bonsai. This will clean out any fines and settle the soil mix and hydrate the bonsai as well.


Repotting your bonsai will keep it from being root bound and starving to death. It won’t keep bonsai small, but fresh soil mix will help feed it new nutrients and allow it to grow and be healthy.

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