Wiring is a key part of bonsai design, but once the wire is on a tree many beginner or even intermediate practitioners are unsure how long it should stay there.
Leave it on too long and there is a risk of scarring, but take it off too soon and it may not have had time for the bonsai to hold the desired position.
In this blog, we'll look at how long you leave wire on a bonsai tree (it's probably longer than you think), as well as the criteria you can use to help you decide whether or not to remove the wire from your tree.
Wiring decisions based on bark
There is no simple answer to how long you can leave wire on a bonsai tree. It can range from a few weeks to several years depending on the tree.
When deciding how to handle bonsai wire, the characteristics of bark are very important.
Many deciduous trees have smooth, thin bark. This bark characteristic lends itself well to elegant trees, such as Japanese maples, but can make life harder when you are wiring.
The reason thin-barked trees are harder to wire is they can scar very easily. If you leave wire on the tree too long and the branch thickens enough for the wire to 'bite' in, you may have a mark on that branch that will take decades to disappear.
For that reason, you need to unwire thin-barked trees much sooner than rough-barked trees. You will usually need to re-apply wire at the same time to continue the development of your design while caring for your bonsai.
A smooth barked Field Maple (Acer campestre). This tree was wired 6 months prior to this photograph. There is no indication the wire should be removed yet, but new growth is appearing so the tree will start to thicken much faster from now.
Rough barked trees have a clear advantage when it comes to wiring. When a wire bites into a rough-barked tree and leaves a mark, it can usually be healed in 1-2 years. Scars will also become much less noticeable much more quickly because the tree will develop new bark that masks the wire scar.
This means we can leave wire on rough-barked trees longer than on smooth-barked trees, which gives branches more time to set in the desired location.
It's worth noting that we are making this decision based on the roughness of the bark, not deciduous vs conifer. Many deciduous trees (such as birch) have rough bark that can tolerate some mild wire biting. It's also worth remembering that the roughness of the bark is a spectrum, so make thoughtful decisions about the tree you have on your turntable at that moment in time.
When to remove wire from bonsai trees
There is no precise time that you should be leaving wire on your trees for. It depends entirely on the growth of the tree and the degree of the bend you have made.
A young and vigorous tree will grow tissue faster, meaning wire will set sooner and also bite into the branch sooner.
Bigger bends also tend to set sooner than subtle bends. This is because there is more damage to the branch during the bending process, and when the tree heals the damage it helps set the branch in its new location.
For thin-barked trees, you may need to remove wire after as little as 6 weeks.
If I have wired a young maple bonsai, for example, I will set a date in my calendar for 4 weeks from the initial wiring. I'll then check the wire weekly. When I first see it's starting to get tight I'll remove it and re-wire the tree. A branch will rarely have set adequately in its new position in 6-8 weeks.
If you have an older, more slow-growing tree it could take 6-9 months for a wire to tighten up to the extent it needs to be removed (as with the field maple pictured above). Just remember to set a reminder for a sensible amount of time in the future, then check your tree regularly.
Rough barked trees can and should be left with wire on longer. With most rough-barked species I am looking for the wire actually biting into the branch as the indication that it is time to un-wire the bonsai.
As mentioned above, these bite marks will not be noticable for long, they are a good marker that enough growth has occured to hold the new branch position.
This wire was applied in March 2021. The species is a Blue Star Squamata juniper.
August 2021, 5 months after wiring, I noticed wire was biting in. It is now April 2022 (8 months after wire removal) and those marks are not visable.
This old larch bonsai has had the same wire on for over a year.
As you can see from these two examples, there is no 'one size fits all' solution for how long wire should stay on a bonsai tree. The first tree is fairly young, very healthy and growing in a large pot to speed up development.
It is expected the younger tree would need wire removed sooner, so bear this in mind when wiring trees in your own collection.
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