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Ginkgo, maidenhair tree - Ginkgo
biloba
General Information:
The Ginkgo is the last member of a family of trees common in prehistoric
times, and was, in fact, thought to be extinct in the wild until
rediscovered in the 17th century in eastern China. It is deciduous, once
thought to be a conifer, but now classed by itself. It is immediately
recognizable by its columnar shape and graceful fan-shaped leaves which
turn a lovely yellow in autumn. Ginkgo tolerates most soil, including
compacted, and alkaline, and grows slowly to 75 feet or more tall. The
tree is easily transplanted and has a vivid yellow fall color which is
second to none in brilliance, even in the south. However, leaves fall
quickly and the fall color show is short. Male specimens are recommended
as the seeds from females emit a rancid odor. However, this is much less
of a factor in bonsai than landscaping as bonsai Ginkgo rarely
fruit.
Family:
Ginkgoaceae
Lighting: Full sun to
part shade. Maximum light is necessary for good autumn color. Very young
trees may need some shelter in midsummer.
Temperature: The Ginkgo's roots have a high moisture content, and
are easily destroyed by frost when exposed to the elements in a shallow
bonsai container. Winter protection of the roots is thus a
necessity.
Watering: Needs a fair
amount of water during growth, but soil should be kept fairly dry ib
winter to avoid frost-damage to roots.
Feeding: Twice monthly,
spring-midsummer and in early September- October.
Pruning and wiring:
Young trees have an open branch structure, but older trees form dense
columns. It is best to style Ginkgo according to its natural shape. Ginkgo
has large leaves which do not easily reduce, so use it for medium to large
size bonsai. Pruning scars will not heal, so avoid cutting large branches.
Shoots grow in clusters of leaves - reduce the cluster to 2-3 leaves with
topmost leaf on the outside. New branches should be pruned back to 2-3
buds while young.Ginkgo is usually shaped by pruning, but may be lightly
wired spring-autumn. Great care must be taken to protect the bark as it is
delicate and scars will not heal. Leaf pruning does not produce
appreciable results. Leaves will reduce somewhat from exposure to high
light levels and controlled watering.
Propagation: Seed,
cuttings or grafting of male specimens. Seed can be sown in spring after
cold-treatment. May be air-layered in spring, or hardwood cuttings may be
taken in autumn.
Repotting: Young
specimens require annual repotting, older specimens every 2-3 years. Repot
in spring, preferably early spring, in basic soil mix.
Pests and diseases: The
Ginkgo is virtually pest-free and tolerates pollution well.
Some species suitable for bonsai:
- Ginkgo biloba 'Aurea' - yellow leaves.
- Ginkgo biloba 'Chichi Icho' - a very desirable cv.,
has smaller leaves and a textured trunk.
- Ginkgo biloba 'Fastigiata' - forms a very narrow
pyramid.
- Ginkgo biloba 'Laciniata' - deeply divided
leaves.
- Ginkgo biloba 'Pendula' - rounded, "weeping"
habit.
- Ginkgo biloba 'Variegata' - yellow and green
variegated leaves.
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