Japanese cedar - Cryptomeria
The tree keeps a billowy pyramidal form on one central trunk until close
to maturity when the crown opens up into an irregular, narrow oval. It
will reach a height of about 50 feet and spread about 20 feet. Old
specimens can develop trunks to three feet in diameter. The reddish brown
bark is ornamental, peeling off in long strips, and is the most pronounced
characteristic on old trees. The foliage will become bronzed during the
winter but greens up again in spring. Branches usually persist on the tree
with old specimens branched to the ground.
Cryptomeria is much loved in Japan as an ornamental
and as a bonsai. Although it is called the Japanese cedar, it is not a
true cedar (Cedrus). It has compact blue-green foliage and peeling red
bark. It has small needles 3/4 inch or smaller. Cryptomeria japonica is
the only species of this genus, but there are many cultivars
Temperature: Hardy in
zones 6-8. If the Cryptomeria is kept outside during winter, it is likely
that the foliage will turn reddish-brown in reaction to the cold. This is
natural, and even though the plant looks somewhat like it is dying, it
should recover in the spring if it is not exposed to temperatures below
its tolerance. Always shield from strong winds.
Watering: Moderate, but
never allow the soil to dry out. Cryptomeria can be quite thirsty in
summer and needs constant checking. Likes misting, and tends to lose
needles if there is not enough humidity.
every 14-30 days.
Pruning and wiring: The
compact habit of the Cryptomeria necessitates vigilant pruning of new
growth, entangled branches and overlapping shoots. This will provide space
for light and air to reach the desired foliage, and reduces the liklihood
of fungus and insect problems. Pinch back new growth, as clipping with
scissors results in browning tips. The plant tends to thicken at
intersections between trunk and branches, so unwanted upper branches
should be removed promptly to avoid loss of trunk taper. Unwanted branches
are often turned into jins. The Cryptomeria is most often styled as a
formal upright, or as part of a forest planting. It is also often used in
sakei. Cryptomeria should be pruned and wired from mid-spring through the
end of summer. Do not work on Cryptomeria during winter. The Cryptomeria
is delicate after pruning and wiring, and should be pampered by shielding
it from sun and wind and misting several times a day for a few weeks after
it has been worked upon.
Propagation: By simple
layering, or softwood cuttings in summer. Cryptomeria can be grafted, but
this is generally done only by professionals. Cryptomeria seeds do not
Repotting: Every 3-5
years in spring, after growth has begun. Root pruning should be very
gradual, and occur a year after selective reduction of the
Pests and diseases:
Pests: Mites and scale can infest the foliage.
Diseases: Leaf blight
and leaf spot are two problems. Leaf blight often causes much of the
interior foliage to brown, creating an unsightly specimen. Fungicide
sprays help prevent the disease, as does placing the tree so it receives
early morning sun to dry the foliage. Keep the foliage as dry as
Some species suitable for bonsai:
- Cryptomeria japonica 'Bandai-sugi': conical
cryptomeria - a dwarf cv which grows to about 6 feet tall.
- Cryptomeria japonica :Jundai-sugi': globular
- Cryptomeria japonica 'Lobbi Nana': dwarf
- Cryptomeria japonica 'Pygmaea': dwarf
- Cryptomeria japonica 'Tansu': Japanese cedar, Tansu
- Cryptomeria japonica 'Tokyo'
- Cryptomeria japonica 'Viminalis'
- Cryptomeria japonica 'Yatsubusa': Japanese red
cedar - a dwarf form with a naturally narrow conical form and compact
- Cryptomeria japonica 'Zuisho'
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