If your bonsai tree is becoming too big for the current pot, it is time to repot your tree! Repotting will help prevent your plant from becoming root bound. When the roots of the bonsai tree fill the pot entirely and the lengthy roots of bonsai are circling the inside of the pot it is a good indication that your bonsai will need to be repotted. Repotting should occur early spring. As the temperature slowly rise in early spring, the bonsai will become active and wake up from their dormancy period. By repotting in the early spring, your bonsai will better adapt to the new pot. The following are some simple tidbits you should consider when repotting your bonsai tree:
(1) When removing your bonsai tree from the pot, carefully lift the tree out and slowly tilt the tree to one side and loosen up the base of the trunk. If the trunk is too hard to pull out gently tap the pot with your hands and loosen the rootball through the drainage hole. Once you have separated the pot from the bonsai thoroughly examine the root ball of the tree. If the roots are crowding around the base of the pot and/or the water takes too long to drain out through the drainage hole, you need to repot your bonsai.
(2) To detangle the roots, shake off about one half of the original soil and use your bonsai rake to comb out the tangled roots. Do not tug on the roots of the tree as it may damage some of the main roots. After you untangle the roots of your bonsai, lightly spray the roots with water. Prune a small portion of the outer brown roots and the thinner roots. When pruning the roots try not to cut too many of the “feeder roots” off. The spacing of the bonsai should be about 1-2cm between the pots edge and the plant.
(3) Covering the drainage holes with some wire mesh is a good idea to prevent the excessive loss of soil. To prevent the mess from moving, use any wire to anchor the mesh down. Add a slightly light layer of gravel
to aid the drainage and a layer of soil.