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Maples - A Deeper Look at Technique


Maples - A Deeper Look at Technique
By Zack Clayton

When you think of maples as bonsai what do you think of? A tree with the growth potential of a controlled weed, inexpensive volunteer stock for experimentation, the japanese maples with delicate foliage, huge leaves, an easy tree to work that back buds readily, or a tree that will stay small for practically ever as a mame?

Wait a minute. Say that last one again.

A lot of books and magazine articles advise that you should let the shoots elongate and then pinch back to two or three buds. Repeat with the new growth. This is generally what I do and it works nicely to get the basic structure in place. But, if I kept that up then every year I would be adding two to four leaf nodes at the end of every branch. How long will it take a mame to outgrow itself at that rate? I grow mostly larger trees but even on a two hand tree it adds up over time.

I don’t usually think about mame size trees at all, let alone mame maples, but there are ways to grow and maintain small maples with tremendous ramification. The key word here is maintain. And I started to think, if its possible to maintain the size and shape of a mame maple for 30 or 50 years, why not apply those techniques to the shohin and larger size trees that I grow? I have them in the size I want and the branch structure is basically defined. Now, what do I do to maintain them for the long term?

Most of these are not instant gratification techniques. For those use the styling and care suggestions in the other Tree of the Month articles that focus on maples. Those articles mention how to thicken trunks and rapidly develop branches and ramification. The methods detailed here will take time to achieve results. But then, they are techniques to hold the line on style and size for our lifetime.

First, be sure that you do everything to maintain the vigor and health of the tree that you can. You will be stressing it with these techniques but they should be okay if they are otherwise in good condition.

In the spring, let the tree grow for 6 to 8 weeks. Then, before the new growth starts to lignify, cut them back to the original bud location and leaf prune everything that is left. In about 2 weeks, you will see new buds forming at the branch ends. Pinch these off also, don’t let them develop. In about another 2 weeks, you will start to see small buds at most of the branch and twig junctions. Take off any of these that are growing vertically up or down, but leave the horizontal buds alone. They will be the basis for your style maintenance. Select the buds that support the form you desire and pinch off the other buds after they leaf out. At some point you will start removing some of the older branches and just use the younger wood/buds for the style and foliage pads. Always arrange to leave one bud on the tip of a branch. This severe pinching is how these trees are kept to a minimum of growth.

If you are preparing the tree for a show, try to time this so that you have new bud and leaf growth about a month old for the display. This whole cycle can be repeated again for central Ohio. Areas with a longer summer or very early spring may be able to push this to 3 times a summer. Just watch out for August and dry heat. These conditions would not be good for this treatment.

If you want to create more branch buds or encourage growth near the branch tips then you can defoliate the entire tree. If you want to let the ramification develop at the tip do nothing more. If you want to force ramification back on the branches, then pinch out the tip buds as they start to develop. To defoliate a tree cut the leaves off at the base of the leaf where it attaches to the stem (petiole). Leave the stem attached to the branch until it dries and falls off. This protects the potential bud and allows the tree to adsorb some nutrition out of the stub as it dies back.

What if you want an area of “weaker” growth to regain its vigor? There are a couple of ways to do this. Just pinch out the stronger leaders and leave the weaker sprouts alone. When you defoliate or do the less severe leaf pruning leave the smaller leaves on interior or weak branches alone. The other method is to continually take off the larger leaves on the tree. If you figure out the average leaf size then pick off the largest 5% of the leaves. You can do this anytime you see large leaves developing and it can be safely continued though out the life of the tree.

Either of these techniques serve to let light and air in to the interior of the tree. Light on the interior leaves means they are producing more sugars (food) from those leaves and this feeds the cambium layers supported by them. Remember that mineral salts and water flow up the sap wood to the leaves, they produce the sugars that the cambium and roots actually feed on.

If you want to increase the girth of a trunk or branch, use sacrifice branches. Leave these branches alone and do not defoliate, leaf prune, or pinch them. They are growth engines and will be removed when they have served their purpose at the end of the season. A sacrifice branch can be left on for more than a year or two, but my experience tells me that for the Red, Sugar, Black, and Norway maples that I work with most of the time, a new branch will give me more growth at the next season plus the pruning scar will be smaller. Since they are maples, there will be plenty of available sprouts on a vigorous tree.

To thicken a whole trunk chose a sprout near the apex, or a sprout that will be part of the future trunk line. To increase taper choose a sprout near (below) the point you want the taper to start decreasing. For a thicker branch, treat it as if you were working on the entire trunk with that branch as the apex. The important thing with this procedure is to select sacrifice branches and sprouts that you can delete without trashing the design. This will usually mean something coming off the back of the trunk or the bottom of a branch. As you get to about 10% of the final height of a tree’s size, but you still want it thicker, try to choose several branches as the sacrifice(s). This will keep you from having one heavy scar or branch stub far up the tree where it would be out of proportion. Two or three smaller scars up there will be much easier to hide.

Wire or pinch for your growth habit as soon as the branch or trunk will hold the shape. Its much easier to shape a 1/8" whip than a 1/4-1/2" stick. The whip isn’t as apt to break and you have more time for the bark to heal if the wire scars it. Actually try to get your wire off before the branch scars. I can’t show data to prove it, but branches that are scarred always seem to take longer to develop. When ever the bark is scarred the tree is stressed in that area and development seems to slow down as a result.

References:
The Secret of Maple Creation. Keiko Harris and Jean Smith. Bonsai Magazine. May/June 1995. pp 8 - 11. (Translated from Bonsai Sekei. Issue 7.)

The History of the Reshaping of a Trident Maple. Yoneia Zuyo. Bonsai Today 32. 1994-4. pp 58 - 62.