In past years demonstrations frequently were somewhat more dramatic than they are now. The demonstrator approached an innocent bush, typically in a five gallon can container, and working quickly, pruned large branches, reduced the root ball so it would fit into a bonsai pot, wired the remaining branches and made jins and sharis as needed. When the job was completed the demonstrator said that the tree should then be placed in the sun and fertilized, and the lucky winner of the raffled tree would then be the proud possessor of a fine bonsai tree. All this in front of our amazed and delighted eyes. Bush to bonsai in less that two hours. It was truly high drama, but most of the audience did not see the grand finale a couple of months later when more often than not the tree died a lingering death that would do justice to the scene where the fat lady dies at the end of a grand opera.

What went wrong? Each of the operations in the demonstration performed on the tree stressed the tree. Most importantly the severe root pruning required to squish the root ball into a bonsai pot deprived the tree of many of the feeder roots which are the very fine roots that supply the tree with water and nutrients. The loss of some of the feeder roots can occur even when the tree is gently repotted. A normal part of the repotting process is to trim the outer roots, and this is where the feeder roots are located. The feeder roots will be replaced fairly quickly, but while they are being replaced, the tree is not able to easily recover from the added stress of heavy pruning and wiring. More recent demonstrations now involve pruning and wiring but repotting is deferred to a later date when the tree has recovered.

If the tree is placed in the hot sun after repotting, the leaves lose more water than can be replaced by the remaining feeder roots, so the tree becomes dehydrated. Fertilizer induces growth that cannot be supported by the remaining feeder roots so the new growth withers.

These factors tell us why trees are normally repotted in late winter months when the weather is cool, growth has slowed, and the trees are not usually fertilized. These conditions allow the tree time to rebuild a healthy feeder root system before the onrush of spring growth.

Heavy wiring and pruning the tree are stressful to the tree but in addition, performing these operations on a tree a short time after repotting can wriggle the tree in the pot if it is not securely fastened into the pot. This can physically destroy the very delicate newly emerging feeder roots. There operations should be deferred for a few weeks after repotting to allow the tree time to rebuilt the root system.

So how in the world do we repot, wire and prune our trees without killing them? First is to recognize that each operation on our trees is stressful and the tree needs time to recover from each operation before the next one is performed. When properly managed, healthy trees survive repotting, pruning and wiring just fine. If your tree is not healthy to begin with, postpone whatever you have in mind until it is healthy. The only exception to this is the unlikely case where emergency repotting in needed as, for example, the potting medium no longer drains well and root rot is in the near horizon.

Repotting always involves at least some of the feeder roots so treat your tree kindly after repotting. Place the tree in the shade for a couple of weeks. After you water the tree, part of the water remaining in the pot simply evaporates and part is taken up by the tree. Since some of the feeder roots have been lost the tree will take up less water indicating that you should check carefully to see that the soil is not excessively wet. Defer the use of fertilizer for a month after repotting. Remember that your tree really wants to grow for you and just needs a bit of wise help and encouragement.