Cryptomeria

Japanese cedar

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, but can grow to majestic heights of over 60 feet. Cryptomeria japonica is the only species of this genus, but there are many cultivars available.

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Lighting:

Partial shade.

Temperature:

Never below 0F, but may be keet indoors in winter. Hardy in zones 7-8. 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.

Feeding:

Spring-autumn, every 14-30 days.

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 foliage.

Styling:

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 germinate reliably.

Pests etc.:

Red spider mites, scale insects. Underwatering, lack of proper humidily, cold weather, harsh sun/wind conditions and extreme pruning/wiring/repotting also threaten the well- being of the Cryptomeria.

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Some species suitable for bonsai:


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Related posts on Cryptomeria:

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Cryptomeria has a tendency to produce extremely compact growth; therefore, it
is critical that the growth be thinned enough to allow for amply light
penetration and air flow. If this does not happen, you will be creating idea
spaces for the development of fungus and insect infestation.  Be advised that
pinching external growth alone will not be sufficient.  You will need to
prune out entangled branches and overlapping shoots.

As for the color of your needles, it would be a good idea to spray your new
specimen with a systemic insecticide and fungicide.  I never introduce a
specimen into my collection without sanitizing the new specimen.

Cordially,

Michael Persiano

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Information Sources:

Information on Cryptomeria is taken from Jahn (ed.) "The Simon and Schuster Guide to Bonsai," Owen's "Bonsai Identifier," Resnick's "Bonsai," the Samsons' "Creative Art of Bonsai," and Tomlinson's "Complete Book of Bonsai," with a little help from a post by Michael Persiano and species information from Thomas (ed.) "The Hearst Garden Guide to Trees and Shrubs."


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