bonsaiTALK Community - View Single Post - Repotting an Established Bonsai (5 parts)

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Twist this wire together with the one at the next corner, and bend the tail of the next wire across the narrow part of the root ball (Figure 25). There is no need for the wires to be tightened too much, since we will finish tightening them all together with the final wire. We are, in effect, creating a wire basket to distribute force evenly around the nebari. The final tightening will cinch the entire basket at once. Repeat with the next wire.

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When you get back to the place you started, you will realize that you have no wire to twist with your final tail. Use a piece of wire of proper length and loop it around the first wire you tied down, twisting it to provide you with the tail you need. You will then twist the two tails together, and this will be the spot you will tighten until the wires hold the nebari snugly (Figure 26).

Add Soil

The tree is now tightly wired to the pot. This technique produces an evenly distributed band of support far enough from the nebari that the bark is not compromised and the tree is completely immobile. Since every tree is different, it is difficult to document every available technique for bridging gaps in the nebari, or working with a difficult root system. However, this is the basic technique that will provide your tree with the security it needs to thrive with normal care.

The time has come to incorporate new soil into the pot. Using a chopstick, carefully work the soil between and under the roots, removing all air pockets as you go around the entire tree. Plunging the chopstick into the soil vigorously and repeatedly is a recipe for pulling feeder roots above the soil.. A gentle circular twirling motion is gentler for the tender roots. Don’t be too vigorous when performing this technique. Try not to mix your regular soil and the drainage layer at this time. When no more soil will easily settle into the roots, remove any excess. Have your helper hold the trunk securely and thump the sides of the pot with the heel of your hand to settle any more soil that might be useful.

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This is where that whisk broom from your bonsai kit will be very useful. It is designed for one purpose: to finish fresh soil added to your pot (Figure 27). Holding it gently, drag it lightly away from the nebari toward the edges of the pot. Proceed all the way around your pot. Excess soil can be collected in your hand at this time and saved for later.

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Bonsai soil should not be mounded up at the tree, it should be flat and level across the pot. If you must mound your soil, your tree is in too shallow a pot. Mounded soil washes away with every watering, so be good to your tree and pot it correctly. The level of the soil should be just below the rim of the pot (Figure 28. ) This will ensure that water will remain in the pot to soak the root zone, and not run over the rim as your soil compacts over time.

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The final step with your new soil is to tamp it with a small trowel. The imported trowels have a pointed tip for getting into corners. This is a cement mason’s margin trowel (Figure 29) left over from a previous career. They are available at any building supply store. The blade tends to be large for some bonsai, but they are easily shaped on a bench grinder. For extremely large bonsai with very low branches, one with a much longer steel handle out to a wooden grip is very handy.

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New Zealand sphagnum moss is a white sphagnum with a very consistent texture. It has none of the negative properties of green sphagnum moss. It is a very simple process to scrub it on your largest soil screen, reducing it to small fibers. A very light sprinkling of sphagnum on top of your soil prior to watering (Figure 30) will help settle the soil and keep it in place, as well as retaining moisture a little better. Water so that all the excess fibers are washed off the pot. Be careful not to use too much!

Water Well

Watering is the last stage in repotting. Using the gentlest shower available, water until the runoff from under the pot is clear. Even freshly sifted bonsai soil retains a good deal of dust, and when you first start watering, this will be washed away. Do not immerse a freshly repotted tree to water it! Immersing the newly repotted tree will just lock the dust into the soil. Your tree is now repotted and ready to go to a protected spot on your bench.

Aftercare

The period after repotting is a tender one for your tree. Keep it protected from excess sunlight and heat (although for tropicals, heat is a key to recovery), and especially from drying winds. There is no need to “balance the top with what you have removed from the roots.” This old wives’ tale will weaken and even kill your tree. The roots you have removed need to be regenerated, and it takes the foliage to do that. Just keep your tree from drying out. After 2-4 weeks, you may begin feeding your tree again, and put it in a less protected spot. You will see new growth as soon as new roots become established.

Conclusion

These are some of the techniques and tools used in the process of repotting a bonsai tree. It is important to learn the principles involved, since every tree is different. Once the principles are established, creativity is the key to supporting and protecting your valuable trees. Good luck and happy repotting!

Contact Chris Johnston at:

bonsaikc@aol.com