The Japanese cedar is a beautiful tree visually and is impressive with its upright form and imposing size. Its Japanese name is Sugi, meaning “straight trunk,” which is evident when you view it from a distance. While the trunk allowed Cryptomeria japonica to be used as the perfect timber tree in Japan, the cultural appreciation for the aesthetic value placed the tree in prominent areas where its attractive foliage and peeling bark can be admired. This stunning tree with its unique foliage creates a fantastic specimen tree to punctuate a garden’s design if the room is available. It creates all-season interest even as an evergreen with its exciting foliage, cones, exfoliating bark, and tendency to form multiple arrow-straight trunks. The Japanese cedar is a relatively easy plant to care for once established in suitable soil with plenty of room to grow. As usual, when planting such a large and long-lived tree, it is important to consider where you plan to plant your tree and even more important to consider that eventually, it will be massive. Planning before planting and taking a stab at predicting future events—such as if you plan is a great idea. Knowing the eventual size and growing conditions take some of the guesswork out of this. Without having to guess, your job of caring for your Japanese cedar becomes a lot easier.
Light
Japanese cedars enjoy the sunlight; however, they do tolerate some shade or filtered sun. The tree will thrive and perform its best in full sun, ideally 6 hours of direct sunlight per day.
Soil
While it prefers rich, acidic, consistently moist but well-drained soil, C. japonica will grow in most average, well-drained soil. Drainage is critical, as soggy soil will lead to root rot or other diseases. The Japanese cedar is somewhat finicky when pH is concerned. It grows well in acidic to neutral soil. It might be a good idea to test the soil pH in the planting area to determine its pH and see if the soil is suitable for a Japanese cedar. If the pH is too high, hope is not lost. A soil’s pH can be lowered by applying soil sulfur, chelated iron, or organic compost.
Water
After it is established, the Japanese cedar will be somewhat drought tolerant. However, when young, these trees will require regular watering to supplement the rain in order for the tree to thrive. When planted in average soil and a location that gets a good amount of summer rain, you should not have to water your new tree daily unless faced with drought conditions.
Temperature and Humidity
Japanese cedar is well suited for USDA Zones 5-8 and is quite hardy in winter and mild heat. One thing that needs to be looked for is the possible winter browning in Cryptomeria japonica. The browning is due to a phenomenon called photoinhibition, which occurs when the tree is under high light and low-temperature conditions. It is not tolerant of pollution and will not thrive in an environment with air of good quality.
Fertilizer
The evergreen will benefit from some fertilization. When feeding the Japanese cedar, use a slow-release fertilizer for trees and shrubs in late winter or very early spring.
Cultivars of Japanese Cedar
The Japanese cedar var. japonica tree is a tree that can reach massive sizes and incredible ages. The tallest Japanese cedars have reached up to 230 feet, while the oldest, a tree named Jomon Sugi, is believed to be between 2,170 to 7,000 years old. If these heights and age are intimidating, there are dwarf Japanese cedar cultivars that do not get much taller than a foot or two.
‘Kilmacurragh’: A dwarf cultivar with a mounding form that has bright green foliage on young growth.‘Black Dragon’: A smaller tree with a wide pyramidal form that has dense, dark green nearly black foliage.‘Elegans’: This is a very popular cultivar that can be used as a shrub or small tree. It has notable brownish red foliage in winter that adds to its seasonal interest. ‘Golden Promise’: This dwarf cultivar has a coarse texture with bright yellow foliage covering its small globular shape. ‘Spiralis’: Is an intermediate form with twisted wiry foliage on densely packed branches. While it starts young in a globular shape, it will eventually establish a leader and take on its mature upright habit.
