What part does Pruning play in Bonsai?
Pruning is necessary to maintain (or refine growth to obtain)
the right shape of a bonsai and encourage new growth. Some
plants naturally respond well to pruning, regardless of how
intense, whilst other plants can find it hard to recover,
especially when pruned at the wrong time of the year.
When should I Prune? To prune correctly you must find out the
type of plant your bonsai is and research when the best times
are to prune old and new season growth. Generally, new growth is
pruned during the growing season to maintain the shape of the
bonsai, whilst pruning of hard wood (old season growth) is done
in mid-autumn.
Forms of Pruning
Finger Pruning One of the main forms of pruning for bonsai,
especially evergreen coniferous bonsai such as junipers and
cedars is 'finger pruning'. This involves pinching back new
growth, which does not come within the general shape of the
bonsai or is at the top of the bonsai helping to encourage bushy
foliage and a more tree-like looking bonsai. To do this, take
the growth between your thumb and forefinger whilst holding the
branch with your other hand and remove with a twisting movement.
This is better than trimming the growth with scissors; this
leaves an unnatural look and leaves the foliage an unsightly
brown. However for deciduous trees, scissor tip pruning is best.
When trimming outward or 'overenthusiastic' growth, trim shoots
back to just after the next series of leaves, but don't cut the
foliage as such.
Branch Pruning Pruning of branches is performed in spring. Much,
but not all of the new growth is removed. Branches are selected
early on as the only branches to be allowed to prosper, while
the excess branches are mercilessly pruned off.
Leaf Pruning Leaf pruning (also known as defoliation) in bonsai
is used for several deciduous and tropical plants to reduce leaf
size, remove unsightly leaves and speed-up growth by causing two
seasons' growth in one. This is done in mid-summer, by cutting
60-90% of the leaves off the tree, only leaving a few to ensure
that the tree keeps its energy. Remove leaves with fine
scissors, cutting them from directly behind the leaf. In the
next few weeks make sure that you keep the plant in a hospitable
position and climate and supply it adequate water. Remember
however, that this form of pruning is only applicable to certain
types of plants.
Root Pruning Bonsai trees are intentionally allowed to become
root-bound in their containers, and the roots too, are pruned.
But root-bound plants won't thrive forever in that condition
and, indeed, bonsai trees must be re-potted every two or three
years to furnish the roots with fresh soil.
Last but not the least, the main factor in maintaining bonsai is
the removal of all but the most important parts of the plant.
Bonsai is all about the reduction of everything just to the
essential elements and ultimate refinement.