Japanese maple

[Tintop]

Is it safe to defoliate this time of year? I have a lot of branches i need to wire and some to remove obviously this will be easier to do without the leaves and i dont want to run the risk of the branches becoming woody and not wireable.

cheers for some advice

[TimS]

I defoliated several weeks back before the real heat hit. If you do it now then you will need to keep the tree out of the heat and wind if you are in an area getting hit by the summer heat now

[Tintop]

Thanks Tim
I have a shaded deck area i can put it and yes im in a spot getting some heat at the moment im about 1 1/2 to 2hrs east of Melbourne

cheers

[bonsaeen]

I thought you would never defoliate a decidious so late in summer? Why waste trees energy?

[shibui]

It is certainly not too late to defoliate maples, including Japanese maple. Some people do it several times a year if needed.
A little shade may be desirable after any defoliation. I have noticed when I take off some larger outer leaves, any remaining leaves get burnt because they were previously shaded by the outer leaves and so are not properly sun tolerant.

[gnichols]

It is certainly not too late to defoliate maples, including Japanese maple. Some people do it several times a year if needed.
A little shade may be desirable after any defoliation. I have noticed when I take off some larger outer leaves, any remaining leaves get burnt because they were previously shaded by the outer leaves and so are not properly sun tolerant.

What are the benefits of defoliating several times a year and do the negatives outweigh the positives?

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[shibui]

There's no simple answer to defoliation and the technique has many variations.
First, defoliation should not be used on trees that are in the growing phase. If your trunk is still developing, forget defoliation because it diverts resources to regrow the leaves so trunk growth will be reduced. Only use it when you are developing branches or refining an established tree.

Defoliation does a number of things:
Takes a lot of energy away from the tree so that ensuing growth is less vigorous = shorter internodes and finer twigs.
Forces new buds to sprout = more ramification (where we had a single shoot without side shoots now we have a shoot with several side shoots) Repeated defoliation will develop ramification more rapidly than once a year pruning.

Selective defoliation can help equalise strength of different areas of the tree. Normally the apex is the most vigorous and shoots tend to grow quite thick up there where we really want the finest twigs. Lower branches are weakest and grow slowly where we would like them to be strongest and thickest. Defoliating the apex but leaving the lower branches with leaves weakens the strong top and allows the weaker lowest branches to get stronger. If you have one weaker branch defoliate the rest of the tree but leave the weak part alone. It should gain vigour.
Tips of branches are usually strong but inner shoots are shaded and are weak. Defoliate or cut outer leaves in half to allow weak inner shoots to get better light and gain strength.
I have seen it used to slow the growth of seedlings destined for shohin or mame sized bonsai. Small internodes in the seedlings will allow closer branching in small sized trees.
There are probably many more aspects that defoliation can help with.

Negatives:
Defoliation takes away resources (strength) from the tree. It could be detrimental to a weak tree. Only defoliate healthy, well fed trees. Repeated defoliation repeatedly weakens the tree. Ensure trees are healthy before any defoliation and perform subsequent defoliation only if the tree appears strong enough to cope.
Defoliation will slow development of younger trees.

On balance, when properly applied, for the right reasons, at the correct time (tree development and time of year) defoliation is a valuable tool in developing good bonsai. It is not a magic bullet. It is not 'to make the leaves smaller' (though that may be one desirable side effect when used properly)

[gnichols]

Thanks for the detailed explanation Neil.

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[Boics]

Defoliation can also result in a new crop of smaller leaves.
This might be helpful or desirable for show worthy trees.
NB: leaf size reduction does not work for all species.