Pruning Your Bonsai to Train the Size and Shape
August 27th, 2006
The whole purpose of the art of bonsai is to create a mature natural appearing tree in miniature. While there are several techniques used to help your tree remain small, pruning is the primary method to accomplish this. Proper pruning will enable your tree to thrive while keeping its miniature size as well as helping to create a pleasing shape.
The frequency and amount of pruning that a tree needs depends on the age, size and type of tree that you are growing. With a deciduous seedling you should not prune it at all the first year and will only prune it a single time during it’s second year. With conifers you should not prune them at all until the third year. When a deciduous is 3 - 5 years old you will probably want to start thickening the trunk. To do this quickly you will want to cut it back when the new growth is at least 2/3rds of the planned height. You should not do this more than twice a year though. Depending on the size and shape of the crown you are trying to achieve you should leave from 1 to 5 leaves when you do this.
If you are willing to wait longer for the trunk of your bonsai to thicken cut back the new growth only when 5 - 8 leaves have appeared. This will slow the thickening of the trunk but will give you delicate branches with few or no visible cutting scars. If your new shoots have produced 1 to 3 leaves then in the late summer the tips of the shoots should be removed. This is called “pinching” and is done either with fingertips or tweezers. This will give the shoots time to harden so that they can produce buds new buds for the winter. At this point if the nitrate levels in the soil are not too high the tree will strop growing and start preparing for winter dormancy.
As your tree grows and matures you will probably need to remove a large branch at some time. To remove a large branch from a deciduous tree you should do it during the peak leaf growing season. This is any time from mid spring to early summer, during this time the pruning scar will heal the quickest. To remove a large branch you will need to use concave or “Wen” cutters. These cutters will create a concave wound that heals better; remember to always use a wound sealant to help your tree recover better.
With a pine or spruce you can safely remove a large branch during the winter as well as during the main growing season.
Proper pruning is critical for the proper development of your tree. It allows you to control the size and appearance to create exactly the visual image that you want. Like many things proper pruning takes time and practice. Be patient and if in doubt about removing something then leave it. You can always cut it off later.

