Japanese tansu is a cultivar of the Cryptomeria japonica. Some trees in this family will grow to 60 feet tall with a 30-foot spread; however, the tansu is a dwarf cultivar that normally grows 6 to 10 feet with an irregular pyramid shape and spread. This fast-growing plant has thick green foliage. It requires little maintenance and is hardy in USDA planting zones 6 through 9. Tansu is an evergreen but the foliage turns a bronze color in colder weather.
Place the tansu where it will get morning sun and not be crowded by other plants. Proper ventilation keeps the foliage drier so the plant does not develop leaf blight or leaf spot, which causes the foliage to brown from the inside.
Water tansu in the early morning so the foliage has time to dry, or bottom water so the foliage does not get wet. Keep the soil evenly moist throughout the growing season. This may mean watering once a week in some areas or every day in others.
Apply a time-release evergreen fertilizer each spring. Sprinkle the fertilizer under the tree so it does not settle around the trunk and water it well to leech it into the soil. Follow the manufacturer's directions on the amount to use.
Hand pick weeds until you notice growth on the tree, then spread a 3-inch layer of shredded pine bark mulch under the tree. The mulch will keep weeds from growing, keep soil moist, and decompose and add beneficial nitrogen to the soil.
Reapply mulch in early winter in colder areas to keep the roots warm. Add mulch in spring in warmer areas as some will have decomposed.