Chapter 91 Cryptomeria japonica

91.1 Cryptomeria, Japanese cedar

A Cryptomeria forest planting, pruned into tight foliage pads. This forest has been in training since 1905. Link to original image.

91.2 Soil: General Deciduous / Rich Conifer Mix

Ratio: 3 parts bark, 1 part grit

Add-ins: dolomitic limestone (~5 lbs/yd), Tree-Tone (15 lbs/yd)

pH: ~6.5 (slightly below neutral)

Moisture: Average

91.3 Light

Routine: mostly to full sun.

Summer: needs to be out of direct sun during the summer and have good ventilation.

91.4 Cultivation Notes

91.4.1 Potting & Root Pruning

Repot every 2 years in mid-spring as new buds start to grow. Older specimens can be repotted according to root development.

91.4.1.1 Top & Branch Management

Triple-trunk Cryptomeria, allowed to grow in a more natural, weeping style. Link to original image.

Heavy pruning: hard pruning can be carried out in Spring. Make clean cuts; the bark and cambium layer separates easily from the wood.

Fine pruning: continual, regular pinching out is required throughout the growing season to spread energy throughout the tree and to keep the trees’ shape. Cryptomeria will backbud very readily from points all over the tree given regular pinching. Do not use scissors to cut foliage as this causes the cut edges to brown as with Junipers.

Leaf pruning: do not defoliate branches.

Wiring:: should be done from April to July. The branches should be bent carefully, because they will break away from the trunk easily. Bend branches over 1/2 inch in diameter slowly over the course of a few weeks; moving them faster can split the bark. Binding branches with raffia before applying wire can reduce the chances of splitting.

91.4.2 Feeding

Feed every 2 weeks from bud extension in April through fall. Feed high nitrogen in spring, a balanced feed starting in June, and low nitrogen to strengthen the root system from August onwards.

91.4.3 Pests & Problems

Red spider mite and scale can cause problems. Mist the foliage regularly to keep their numbers down. Do not use insecticidal soap or horticultural oils, because they can burn the foliage.

91.4.4 Winter Storage

Needs some protection from frosts. Mulch thoroughly. Leaves commonly brown during the winter but brighten back to green in the Spring.

91.5 Propagation Notes

Sow seed outside in Spring. Cuttings root very easily in late summer/early autumn from ripe wood. Available in nurseries, but not widely sold.

91.6 Artistic & Styling Notes

Does well in a less formal, more natural style, with single or multiple trunk styles.

91.7 Additional Information

91.7.1 Natural History

Cryptomeria is native to the forests of China, Korea and Japan. It is known for its naturally conical habit and its thick, red, fibrous bark.

Cryptomeria is a slender, pyramidal, evergreen conifer with tiered horizontal branching, which is slightly drooping at the tips.

91.7.2 In Cultivation

Cryptomeria is commonly known as the Japanese cedar, but is actually in the same family as yews (Taxodiaceae). It is the national tree of Japan where it is often planted at temples and shrines. There are several cultivars, including dwarfs like ‘Elegans Nana’ and ‘Globans Nana.’