Since bonsai trees are grown from ordinary, not dwarf, species, their small size is primarily the result of pruning, both branches and roots. When it comes to bonsai, much learning and experience is required for proper soil preparation, watering and other skills needed for bonsai trees. But no other aspect is so critical as bonsai pruning for making the bonsai more than just a small tree. Itâ€™s the key to making it a fine work of art through proper bonsai shaping.
Before even pulling the shears from the drawer to start your bonsai pruning, itâ€™s best to start with a conception of the final goal desired. Hand-sketching or gardening software can be a big help here. Create a vision, on paper or monitor, of what you want the final bonsai tree to look like. Then you can begin to develop the proper techniques.
â€˜Finger pruningâ€™ is at the top of the list of bonsai pruning skills needed. For Junipers and Cedars and other conifers, this involves pinching new growth off the bonsai trees wherever shaping and eliminating is carried out. Simple in theory, just support the tree or branch with one hand and take the new growth between your thumb and forefinger in the other. Remove with a sharp twist, but avoid pulling on the branch or tree.
It will take some practice to be comfortable with this technique of bonsai pruning. Rather than damage your valued bonsai trees, gain some familiarity first by performing it on a small bush. Once you can remove the growth cleanly without tugging on the plant, youâ€™re ready to use it on your bonsai.
For deciduous bonsai trees, such as Maples, the Chinese Elm or others, scissor tip bonsai pruning is best. Trim the new shoots back to your imagined point based on the sketch. Leaf pruning or defoliation is also common for some deciduous trees and bushes, such as a ficus. Carried out in mid-summer, you simply remove half of the leaves with a pair of fine scissors. Leave the stems intact.
Bonsai pruning is carried out primarily as a component of bonsai shaping in order to achieve the desired look. Root pruning, which should be carried out in concert with a branch pruning regimen, affects the basic health of the tree.
Pruning branches and leaves will affect root growth. Fewer leaves and branches means less for the root system to supply with water and nutrients. Heavy branch pruning of bonsai trees will slow the growth of the root system.
Nevertheless, roots should be examined at least every two years, since bonsai pruning also involves the roots. Depending on the age and species of bonsai tree, and the size of the pot, roots can be become root bound. Though roots will naturally curve somewhat inside the soil, when they encounter a hard obstacle such as the side of the pot, they curve inward. Eventually they have nowhere else to go as more roots occupy the available space.
Before that happens, they should be trimmed with very sharp scissors. Trim back existing roots to about two-thirds their current length, eliminating a few younger and a few older roots. Be sure to leave ample number and length. Re-pot into a larger pot for larger and older bonsai trees.
Proper bonsai pruning times are dependent on the various species of indoor bonsai trees, but you can take the full-sized species as a guideline. Some are pruned at the start of growing season to stunt growth, others at the end in order to leave less prior to the dormant period.