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Wiring Bonsai for Better Shape Outcomes

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Wiring is a useful technique for speeding the development of bonsai. The basis of wiring bonsai is selecting a suitable gauge wire and wrapping it around the branches, using the metal’s tensile strength to manipulate a branch’s growth direction.

Good wiring takes lots of practice to do effectively. Work towards using as little wire as possible to achieve your goal. Selecting the right wire balances cost and function, with the copper wire being stronger (but more expensive) than anodized aluminum wire.

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Low Voltage Wiring
Low Voltage Wiring

The Right Material for Bonsai Wiring

Anodized aluminum and annealed copper wire are recommended for use on bonsai. Telephone, electrical, and galvanized cables should not be used.

Wiring Bonsai for Better Shape
Wiring Bonsai for Better Shape

Annealed Copper Wire

For copper wire to be used on bonsai, it must first undergo an annealing process to make it more malleable. A common electrical earthing wire is too hard and difficult to bend around branches.

Annealing involves heating the wire to a temperature above 700 degrees Fahrenheit (400 ⁰C), causing the structure to create and grow new grain free of strain. While you could do it yourself, the results generally produce an unsuitable product with flat spots or kinks.

Annealed copper wire can be costly but much stronger than aluminum.

Various Bonsai Wire
Various Bonsai Wire

Anodized Aluminum Wire

Aluminum wire is anodized in either black or brown to camouflage the shiny wire so that it does not appear too unsightly when applied to your trees.

The anodizing process does not fundamentally change the aluminum wire’s properties.

Aluminum wire is very soft and forgiving, allowing you to correct any mistakes you may have made when applying the wire.

Aluminum wire is preferred for trees with thin bark, such as olives, maples, and elms, as it will not damage the bark.

However, it does not have the tensile strength of copper wire, allowing some branches to return partially to their original position.

Raffia

You must watch out that the live tissue does not separate from the wood below while making greater bends in conifers. You’ll need to utilize something to wrap around the branch or trunk to accomplish this tightly.

The conventional approach uses raffia. After soaking the raffia in water, pick off a few strands and tie them at the end.

When you start wrapping, leave a small amount of raffia sticking out so you have something to tie the end off with.

The portion to be bent should be carefully wrapped, and the knot should be tight. As usual, wire. Use pliers to bend the wire, which then bends the branch, being sure to hold the outside of the bends.

Selecting The Right Wire Gauge

Let the thickness of the branch guide your choice. Rather, wire the branch from the trunk until the first fork, then make one or two turns after the fork and terminate the wire, continuing with an appropriate thickness for this next section of the branch.

Annealed Copper Wire Gauge Guide

Copper is much stronger than aluminum, and the wire strengthens with use, allowing you to use much thinner wire. As a rule, use a wire roughly half the thickness of the branch needing to be wired.

Anodized Aluminium Wire Gauge Guide

Aluminum wire is rather soft, offering limited hold. If a length of wire equal to the branch cannot remain straight when held vertically, you need a thicker wire.

Normally, the wire should be roughly the same as the branch’s thickness – or about two-thirds.

Trunk Wiring Guide

Using wire will generally be insufficient to bend a thick trunk. Here it would help if you protected the bark with raffia first, then apply thick wire.

Use a branch jack, a system of wire stays, and metal rebar to effect the bends you want.

Using Anchor Wires

Anchor wires help when wiring branches
Anchor wires help when wiring branches.

Wiring a branch involves wrapping wire around the branch, sufficient to allow you to bend and angle the branch.

However, the applied wire can move if not secured properly. As the wire moves, it can (and usually does) tear off the bark, particularly in the case of species with thin bark, such as olives.

The use of an anchor wire can help prevent this from happening.

Anchor to the Trunk

Secure the wire by inserting a reasonable length into the growing medium close to the base of the trunk, with no gaps, and then coil it at least twice around the trunk.

A wire is then attached to the wiring on the branches to pull them down.

You can wire two branches simultaneously, my preferred method, or just from the trunk to the branch.

Branch – Trunk – Branch

Before going onto the branch with the wire, ensure the branches are not exactly across from one another; otherwise, they will see-saw when you bend them.

You should also be able to wrap the wire at least twice around the trunk.

Trunk – Branch

Before continuing to the branch, make at least two coils around the trunk.

Getting Spacing Right When Wiring Bonsai

You will notice in many books on bonsai, in the section on wiring, that they have these neat 45-degree angles between the branch and the wire loop. In my opinion, this angle is not entirely functional.

I have found that 30 – 35 degrees are more widely used, and I have also found that putting even these ‘‘lose’’ angles in at all is completely unnecessary unless you plan on putting tight bends into the branch.

In reality, you only need very gentle curves, so the wire angle can be even less as it is all needed to hold the gentle shape you have created.

I want to emphasize that you consider the angle; use the right angle for the bends you want to do and keep the angle consistent.

Avoiding Gaps

Gaps are areas without contact between the wire and the branch. When you bend the branch, and you bend at such a point, you need to ‘overbend’ the branch for it to remain in more or less the position you want.

However, gaps can cause branches to snap, so they are best avoided.

Getting Spacing Right When Wiring Bonsai

Which Season Is Good For Wiring a Bonsai?

Bending a branch causes minor cracks in the bark and cambium, which mend faster during the growth season.

After a few weeks, the new branch position usually becomes stable in deciduous trees. These procedures take a lot longer outside of the growing season.

Spring

Early spring is a good time to wire outdoor bonsai, pre-budding, and before leaf growth that will interfere with wiring operations. However, after budding and leaf growth, extra care is needed not to cause damage.

In April-May, the shoot growth is particularly strong, allowing rapid healing and shape adoption. It must be checked regularly, and it may already be necessary to unwire the bonsai in May.

With many deciduous tree species, however, the new position has already solidified, so the branch retains its position.

Summer

In summer, the existing leaves can interfere with the analysis of the branch structure and wire wrapping operations. The main growth is over, so the wire can stay longer on the tree without becoming embedded.

At the same time, the bonsai growth is sufficient to close the wounds and stabilize the new shape quickly.

Extra care is needed when wire wrapping in summer as the xylem flow from shoots to roots is high, and the bark is more inclined to separate from the wood.

Autumn

For deciduous bonsai in warmer regions, early autumn is a good time to train branches as the strongest growth has ended.

Wire wrapping can remain in situ until April the following year. The new buds are still very small, and the danger of breaking them during wiring is low.

Winter

Avoid winter wiring as any micro-damage caused will not heal. Since most trees are dormant, rather wait for spring.

Indoor bonsai from the subtropics can be wired throughout the year if the environment permits. Evergreen conifer species can be wired from spring to early autumn, requiring extended wiring to train the tree.

Bonsai Wiring Risks

Damage Caused By Wire

By wrapping the branch in wire and bending it, you effectively make little breaks in the branch and hold it in place while they mend. This also occurs when a cast is applied to a broken arm or leg by a doctor.

Coincidentally, this is also why you might occasionally lose a branch after wiring; you might do this because you were unsure and bent the branch too many times, causing too many breaks for the plant to repair.

This is also the reason why you shouldn’t wire in the winter.

If a branch cracks at any point, you should instantly seal it. Use a high-quality sealant for conifers, such as Japanese cut paste, to establish an airtight seal behind which healing can occur quickly, thanks to the hormones added to pastes.

You should be careful if you wire in the early spring before your deciduous trees start pushing new growth since wire bites will happen in weeks.

When you put a wire onto a branch, the branch thickens or swells in between the wire because it cannot tolerate greater sap flow when it is in contact with the wire. In extreme circumstances, it will ingest the wire.

Wire bites can hasten the thickening of a branch in some species, such as pines. In junipers, wire bite can be used to assist in creating a novel and fascinating sap flow before tissue is removed to produce Shari later on.

It would help if you generally prevented serious wire bites, though. A little bit of wire removal is normal and helpful, but if you do it too soon, the branch will likely move, and you will need to wire it again.

You want to avoid wire bites like the plague on thin-barked trees like Japanese maples, olive trees, azaleas, and others. It takes thin-barked trees several years to “shed” the wire bite scars.

Removing Wire

There is no need to remove the wire before the tree starts taking quite a bit out of it. It may just be a trait of this specific black pine or the limbs on this tree may be quite old, but I found them quite brittle.

Once the wire is removed and the branches are not disturbed, the severely flaky bark I wired off will eventually grow back.

Another justification for the effectiveness of utilizing guy wires is to avoid disturbing the bark on older branches and trunks.

There is no need to use any wire wrapping; insert a screw to anchor the guide wire on both sides and tighten.

I strongly advise using a branch jack on thick branches and trunks to make this bend slowly and under very tight control.

Removing Bonsai Wire
Removing Bonsai Wire

I understand that everyone likes to save a little money, but is it really worth saving an inch of aluminum wire at the expense of losing a branch?

Yet, despite the danger, I often see people unwinding wire and spending a day trying to straighten it to save it.

Carefully unwinding bitten-in wire with jin pliers or, I suppose, long-nosed pliers is advised. Relax till you have the first chance to cut it.

A wire that hasn’t bit into the wood can be cut off immediately. It would help if you used a wire cutter manufactured specifically for bonsai to accomplish this. In stark contrast to homemade pliers, it:

  • Bonsai wire cutters have a stubby nose which prevents you from damaging the branch when you cut the wire.
  • There is sufficient metal at the cutting edge to enable you to easily and safely cut even thick aluminum and copper wire without the tip breaking off.
  • The pivot point is very close to the cutting edge, so you can perform many successive cuts easily and without tiring (this is important when removing wire from a large tree!)

In Closing

Bonsai wiring allows the artist to train their tree in the form or shape wanted. Having a clear image of your goals is always advisable, avoiding rewiring and rebending as each change of mind can cause damage.

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