Knowledge of Bonsai

From my earliest days in bonsai I was taught, and the books confirmed the myth, that the reason for defoliation was to reduce the size of foliage. The truth of the matter is that defoliation is not primarily designed to reduce foliage size but to increase ramification. The increased ramification is the reason for the reduced size of foliage.

All that is necessary to understand this principle is to attach more than one hose to a spigot and turn on the water to one hose, then two, then three and as many as you have assigned. Considering that the amount of water coming out of the spigot remains constant you will notice as you increase the number of hoses to the one water source the volume and force will diminish that comes from any one hose as compared to the volume and force that will come from only one.

The same effect manifests itself in the process of defoliation with the creation of many more outlets for the tree to service than it had before it was defoliated. Therefore the increased ramification will produce smaller growth.

As a warning it must be pointed out that defoliation does not work well on all trees and in some case may prove to be fatal.

The primary reason for defoliating a tree is to increase and speed up the ramification progress. The smaller leaves and (to some) more beautiful or intense autumn colors are side effects.

Secondly, defoliating a tree in certain areas alone can be used to balance a tree as well. Defoliating the area that has the most vigorous growth causes the less stronger areas to increase in vigour.

Also, I think it's best to not completely defoliate a tree as you put the growth to a total stop for a while. Maybe it's better to selectively defoliate the tree so that growth can continue.

Watch your watering just before and after defoliation, as the decrease of foliage causes the tree to need less water. Defoliation should further more only be done on strong trees as it takes a lot of strength for the tree to feed the new growth.

This is what I know of defoliation.
Correct me if I'm wrong.

Grts,

Chris

These are some excellent tips on defoliation. It can be fatal or very damaging to fruiting trees, especially. Balancing a tree is one of the best reasons to practice defoliation. And strong trees recover far better than weak ones.

To make it more specific, which species do you practice defoliation on, and what results do you get? Acer buergerianum is the most well known subject, and can be completely defoliated several times a season, depending on one's climate and the health of the tree. Acer palmatum, on the other hand, are less vigorous and usually are only defoliated by removing the largest leaves.

I have been warned against defoliating Carpinus coreana. They can tend to be slow rebudding, as I found out last year. However, I believe it was because I had not fed the tree strongly enough. I defoliated completely this year and was rewarded with an excellent budding.

Does anyone else have any helpful tips or principles they follow?

To my best knowledge a Carpinus can be defoliated best by removing leaves selectively around the tree instead of defoliating it completely. Only remove the largest leaves and the ones at the tips of the branches. You will be rewarded with better ramification closer to the trunk side of the branch.

Further, I have had fine results with defoliating Acers palmatum.

It is commonly accepted that fruiting trees cannot be defoliated as it will kill them, although that a very good bonsai friend of mine has several fruiting trees, among wich oranges, citrus and apple trees, and he has had succesfull results with defoliating them.

I have different experiences with some of the species which are mentioned above.
Defoliation of fruiting trees works for me. I have several fruiting trees like: citrus-,apricot- and apple-trees. The apricot and apples are deciduous trees and these trees I defoliate to refine them. Particularly the apple-trees respond very well. When I defoliate these trees I never let them bear any fruits. And I never defoliate when a tree is not in excellent condition.

The citrus-trees I defoliate for another reason. These trees are evergreen and the leaves of the species I have are vey large. I keep this trees outside in the summer and inside my house for the winter. They start to grow in January but keep also their old leaves.
When the temperature starts to raise above 20 degrees Celsius I take them outside.
After a few weeks outside I defoliate these trees. They reward me with lots of small, shiny leaves. The size of these leaves are about 20% of their original size. These leaves I keep for another year. So I use the side effect of getting smaller leaves after defoliation. The weather is a defining aspect in the new growth. A warm sunny period results in smaller leaves. Because the weather is variable in Holland the effect is not the same each year.
Never do this when your tree is not in a excellent condition!

Chris Johnston wrote:Does anyone else have any helpful tips or principles they follow?

While defoliation does help in the ramification process as explained by Van but reducing leaves' size is definitely one of the reasons for defoliation which is widely practiced in the tropics. I do agree with Van's views but when I attempt to reduce leaf size, I go for complete defoliation particulary with Ficus rumphii, Ficus long island, Ficus bengalensis, Barringtonia and even Bougainvillea........the nice ramification I get in the process is a bonus!

Ficus religiosa on the other hand does not respond well to more than once defoliation, and at times results in die-back of stems.

I have had great success with defoliating Ficus retusa. However, I left a large leaf or so on each branch in order to encourage continued energy movement to the branch tips. Better safe than sorry.

Great leaf reduction and budding results though.

-David

Sometimes ficus retusa will show dieback
after total defoliation,especially if you
place it immediately back into the sun.

Regards,
Dorothy Schmitz

Very good to know.

-David

Hello friends.
For me defoliation is a wonderful weapon...

Olive trees
All oaks including suber or evergreen ones
All carpinus
Fagus sylvestris (our european fagus). No experience with the japanese one.
Ficus carrica.
Ficus
Carmona
Buxus
Apple trees
All maples

Well. Now we have to know that there is always a good time to do that.

Ficus for instance (in France) between june and end of august)
I take off all the leaves and cut the tip of the branches. When large leaves appear after a defoliation I immediatly cut them...
We can defoliate Two times in a year in France

Olive tree : only when the weather is warm. Like ficus. Two times in a year also.
Here we can let two leaves at the extremity of the twiggs, but it's not necessary.

Oaks , fagus, carpinus in june.... Later is possible too.

After a defoliation I let my trees in full sun, without problem. the leaves are smaller so.

Buxus, only if strong, and on south varieties (In France we have lots of buxus and specially two varieties uin south and north.). In june. Later sometimes it's very long to see new leaves....

I forgot : it's also a good time to wire

An exemple with a ficus carica. Defoliated for the Ginkgo 2003





And now in 2007 at the Versailles exhibition (may 2007)

Very interesting post! I especially appreciate the tips of Mr. Sacal. I would also underline importance of mekiri on quercus, when the new growth color is turning from green to reddish to grey, before lignification, around middle june. That lignification phase is a good time for a lot of deciduous trees. When I was working in italy ( I worked for a yamadori nursery for around eight years before moving abroad) I was used to wire new growth before that phase, without cutting until change of color, then take wire off while operating mekiri, waiting till end of july for the second growth, and wire again. You accellerate cultivation a lot, and in this way power fertilizing doesn´t increase leaves´ size!! If the tree is strong, expected good reaction always follows.

It´s also a good chance to remember summertime, here in dark berlin autumn.. sigh!!


regards,

andrea melloni

Thank you Andrea (I met you at Arco in 2000 I think, and bought a quercus alba you worked. World is pretty little..)

Mekiri is a very very important technique !

I remember Arco pretty well, it was a pleasure to meet You! I was there in 2007 too, this time just as demo, with a big mugo pine cascade. Maybe we´ll meet again there next year! World is really little sometimes!

I do agree with You about mekiri importance, and the T (time) factor is of highest relevance!


regards,


Andrea