Wiring essentials

by Neville Coxon

The purpose of wiring a bonsai is to change the direction and shape of branches and trunks and to make them conform to the artist's design. Then by pruning the tree later on it may be shaped and proportioned. Wiring should be kept neat. First from an aesthetic point of view and secondly from a strength point. Messy wiring may do the job but is less efficient and less economical.



I think with the prices of wire today it does not make much difference whether it is copper or aluminium. Whichever you use, use economically and carefully unwind it when the branch has set. Before re-using copper wire you will have to anneal it, i.e. make it soft and pliable. To do this, it should be placed in a low-heat fire and left till it reaches a cherry red colour. Do not use too much heat and do not leave it in for too long or it will become brittle. The wire should then be left to cool slowly. It is best to straighten the wire before annealing as it will harden up when you bend it again.


Has the advantage that it does not harden like copper so it will not be necessary to anneal it before re-using it.

When starting to wire a heavy trunk the wire is anchored by pushing one end into the ground at the back of the base of the tree, if possible behind a strong surface root, and then wound around the trunk keeping the turns at an angle of 45 degrees, to the horizontal, as seen from any side of the tree. The trunk should be wired first and then the branches. The wiring should be firm but not too tight or it will bite in as the tree grows. If it is too loose it will not hold the trunk or branch in place. It is sometimes possible to twist the upper part of the tree while you are wiring so as to bring a branch into a better position but this must be done with care or you could separate the cambium from the wood, and ring barking will result. If the spirals are too close, say the angle is 20 degrees, the wire acts as a spring and will not hold the tree in place. If spread too wide, say a 60 degree angle, the strength of the wire will be lost. Wiring at 45 degrees makes use of all the strength in the wire. To determine the length of wire required, measure the length of the tree or branch and add another third of that length. It is better to have too much than too little.

There are other methods of bending or shaping a heavy trunk.

  1. You could use a "U" -bolt and strong iron rods and wood braces.
  2. You could use a special jack and rod with a wood brace.
  3. For straightening a trunk that has perhaps bent too far you could use a jack and rod and wedge.
  4. When all else fails you could use two blocks of wood and a plank and a "G"-clamp but whichever system you use, take care that you do not damage the cambium.

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Random Bonsai Tip

To thicken thin branches make a cut just below the branch or a bud on the branch. The sugars produced in the leaves of the tree move down to the roots through the phloem, this flow of sap is interrupted by the cut and the accumulation of sugars above the cut increases the vigour as it is used by the bud, forcing it into action. As soon as the wound heals the normal sap flow resumes.