Article written by Gary English and published on this website with kind permission of The Gardener magazine.
© Gary English gary@cybersmith.co.za
© The Gardener Magazine - Editor: Tanya Visser tanya@thegardener.co.za
Pruning
Pruning is a basic and essential technique for any bonsai artist to master. Beginners often are reluctant to prune a tree, believing it to be cruel in some way. Actually the opposite is true. Pruning a tree stimulates its growth, and extends a tree's longevity. Trees in nature will be "pruned" in many ways, animals browse on them, branches break from weather and many will die off due to being starved of light by other branches and creepers. You mow your lawn!
The bonsai artist must imitate these natural events and combine them with our creative energies to produce a magnificent living sculpture.
On a more pragmatic level pruning the ends of a branch will redirect the sap lower down the branch. This will cause new shoots to sprout from the nodes in the branches. The main area of new growth will be the two nodes closest to the cut end. The position of the node will indicate the direction in which the new branch will grow. This is directional pruning. Along with wiring it is the main technique used in styling any bonsai.
On some species of tree the end of the cut branch tends to die back to the first node. If cut too close to this node the die back may damage the node. It is best to cut a centimeter or two away from the node. The dead end can be trimmed back later. Acacia are particularly prone to this problem.
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Another form of pruning involves the removal of all, or almost all of the leaves. This puts the tree into a spring cycle. A couple of weeks later the tree will put out a new set of leaves. This must only be done once a year toward mid-summer and only on healthy trees.
Defoliating can also be carried out on a tree that has been severely burnt by the sun or dried out by lack of water. Removal of the withered leaves will reduce the stress on the roots and allow the tree to recover.
Tools for pruning trees can range from delicate defoliating scissors to power-saws. A noted speaker at the recent International Convention in Pretoria claimed to have used a set of electric hedge clippers in a demonstration in the USA, much to the bemusement of his rather conservative audience. Branch cutters are probably the most commonly used tool and should be the first purpose-made bonsai tool one should buy.
Whatever tools you use they must be sharp, and always be cleaned after use. Parasites and disease can be easily transmitted from one plant to another via dirty tools.
The best time to do major pruning is just before the sap begins to rise, late winter or early spring for most plants, although I do small amounts of pruning throughout the year whenever a branch gets too long, or whenever that manic desire to JUST DO BONSAI hits me.
The last trick, and one that too many folk forget to do is to seal any large cuts with a sealant of some sort. There are many specialized products for this but I find wood glue, (Ponal, Alcolin and many other brands) the most convenient. Although it is milky white in the bottle, it dries clear, is not too difficult to remove at a later date, and best of all is cheap.