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Spruce
have a poor reputation as bonsai. Difficult to style, difficult
to encourage the branches to set into new positions through wiring and difficult to create good ramification with little if any prospect
of backbudding.
Unfortunately, the ubiquitous Picea albertiana 'conica' has not
helped matters; very often picked up by beginners looking for
nursery trees to style into bonsai, the Alberta spruce has been
known to cause great annoyance and frustration!
However, there are some excellent examples of Spruce bonsai in
Europe and Japan; the genus as a whole has some excellent qualities
and very often, it is just a question of learning how to work
with Spruce and its foibles so that the best can be made of this
tree.
This article is primarily based on my experience of Picea albertiana and Picea pungens though these techniques can also be applied with degrees of success on all vigorous Picea/Spruce bonsai.
Spruce vigour
The techniques
described in this article assume that your Spruce is vigorous
and that care is taken when applying these techniques to weak
lower and inner branching.
The easiest way to judge the vigour of a Spruce and its individual
branches is to look at the number of new buds that have formed,
very often at the tips of the foliage, in late Summer.
Branches
with no buds are very weak and are likely to fail/dieback in
the following Spring. These are best left alone.
Branches with one bud are weak and will tolerate minor wiring
and needle plucking.
Branches with two or more buds are strong to very vigorous and
all of the techniques described can be applied.
Timing
Spruce are
sensitive to timing. In particular, styling and wiring must
not be carried out while the tree is in active growth as branches
are very likely to fail and dieback.
In the UK, extensive styling is best carried out from late Summer
(August) through to the first frosts around November.
Wiring
Spruce have
incredibly supple branches. With the use of thick enough wire
and guy wires, branches of over 1" can easily be bent without
danger of snapping or cracking. Thinner mature branches can
be bent and contorted in a variety of directions to bring the
foliage closer to the trunk.
This suppleness is also problematic; wired mature branches can
take years to set into their new position, often requiring repeated
rewiring. However, I found that on a number of occasions, branches
that have had twists and turns put into them have set into position
within a year.
When branches of any tree species are wired into a new position,
the cambium is broken (however minutely) and the repair of the
damaged parts of the cambium layer, by the tree, sets the branch
into its new position. With Spruce, it would seem that more
manipulation is needed to damage the cambium in order that the
tree will be prompted to repair the damage and set the branch.
However, care must be taken as major manipulation of a Spruce
branch in the late Spring and Summer will cause it to dieback
very quickly. This is why Spruce should be styled from August
onwards. After this time I have found that Spruce are very tolerate
of all wiring and styling.
Styling
Featuring
short needles and very often an overall dense foliage mass the
Alberta Spruce seems eminently suitable for bonsai but once
the bar branches have been removed, the enthusiast often finds
that he is left with a small number of thin, ill-spaced branches
that only have foliage growing on the tips.
When considering which branches to keep and those to remove,
always value and retain those that have foliage closest to the
trunk. Though backbudding can be promoted on Spruce, this will
always be limited. Do not rely on any backbudding on the trunk
or old branches unless the tree has been very heavily pruned
back.
5" tall Picea glauca 'Albertiana'
Unless a
Spruce has been specifically trained in the ground for bonsai
and the branches are appropriate (short with foliage near the
trunk), the most suitable design will be one that uses the first
2 or 3 branches with the uppermost (remaining) branch used for
the new trunkline and imitates a wild tree or yamadori.
If one studies pictures of good quality Spruce bonsai on the
internet or in books, as with Juniper, many of the designs use
only a very small number of primary branches (that is branches
that grow directly from the trunk) but have had many secondary
and tertiary branches developed to greatly increase ramification
and foliage density.
Unless you have suitable raw material with the appropriate sized
trunk and short branching, informal or formal upright Spruce
bonsai are very difficult to style realistically or to any real
quality.
Pruning Spruce
Left to
their own natural growing pattern, Spruce will produce one flush
of growth each year. New shoots extend from buds set in the
previous year; these buds are nearly always at the tips of the
branches. Backbudding without some kind of pruning regime is
very rare.
Without some forward planning and planning, all the needles
of the tree will be on the tips of the branches leaving otherwise
bare branches.