Bonsai Defoliation

Part 21 of a series by Eugene Howell

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Plant close upEvery once in a while I’ll see a bonsai on display that’s really outstanding. I’ll stop and take a good long look at it trying to figure out what makes it so attractive. In addition to the perfect branch placement, the outstanding ramification and beautifully formed leaf pads, there’s a little something extra that seems to make it a perfect bonsai. After studying it for a little while, and knowing something about the particular species, I’ll realize that it’s the leaves. The leaves are in perfect proportion to the size of the tree and this is what makes it look really good.

Bonsai tree’s are supposed to resemble full grown trees but on a very small scale. Frequently, however, people will bonsai a species of tree or shrub that has naturally large leaves. The end result is a bonsai that does not resemble a full grown tree because the large leaves are way out of proportion compared to the twigs and branches.

The Japanese, having created the art and worked with bonsai for hundreds of years, have long ago learned how to use nature to correct the disproportional sizes between leaves and tree. To do so, they employ the technique of leaf reduction through bonsai defoliation.

To understand how this works, let’s review some information we’ve covered in previous articles.

The cambium layer in all plants consists of meristem cells. These cells are the only ones in the plant that can form into anything needed by the plant. What this means is that meristem cells can turn into roots, leaves, branches, bark, or flowers. The meristem cells at the tip of each branch are dominant and produce a chemical to prevent buds further down the branch from growing.

When the dominant cells are removed by pinching or pruning the branch tip, these dormant buds will awaken and develop into either new leaves or new branches.

Think about deciduous trees. They lose their leaves in winter and grow new ones in spring. Where do the new spring leaves come from? When spring arrives, all the dormant buds at the base of where the old leaf stems had been, come out of dormancy and grow into new leaves. The tree, having had the previous summer to store up food, has plenty of food available for these new spring leaves to grow to their full, natural size.

What happens if the tree loses all its leaves again while it’s still spring time? Dormant buds kick into action yet again but this time the tree doesn’t have the food storage enough to grow these leaves to full size. Thus by defoliating your springtime bonsai, you’ll be able to effectively reduce the size of the newer leaves.

(Continued in part 22)

Photo credit: flickr Creative Commons, Plant Close Up by Josh Dang

Part 20 of this series : Part 22 of this series

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