The Japanese Cheesewood, Pittosporum tobira, is a versatile and attractive evergreen shrub, admired for its dense foliage and sweetly scented flowers. Its adaptability makes it a popular and resilient choice for many landscapes.
Understanding Japanese Cheesewood
Japanese Cheesewood is an evergreen shrub native to East Asia, including Japan, China, Taiwan, and Korea. It has leathery, dark green leaves, typically oval and up to 4 inches long, with glossy upper surfaces that provide year-round visual interest. In spring, it produces clusters of small, creamy-white flowers with a sweet fragrance reminiscent of orange blossoms. These blooms often fade to a dull yellow.
This shrub exhibits a dense, rounded growth habit, reaching 8 to 12 feet tall with a similar spread, though some can become treelike. It grows relatively fast when young, slowing with maturity. Japanese Cheesewood is hardy in USDA Zones 8 through 11.
Cultivating Japanese Cheesewood
Light Requirements
Japanese Cheesewood adapts well to a variety of light conditions, thriving in full sun to partial shade. While it can tolerate heavy shade, growth may become leggy, and the foliage might appear darker and larger, potentially reducing the abundance of flowers. For optimal flowering and dense growth, providing at least 4-6 hours of direct sunlight daily is beneficial. In regions with intense summer heat, some afternoon shade can help protect the plant.
Soil and Drainage
This shrub is not particularly demanding regarding soil type, but it performs best in well-drained, fertile soil. It can tolerate a wide range of pH levels, from slightly acidic to neutral, though it adapts to both alkaline and sandy soils. Proper drainage is important to prevent root rot, which can occur in poorly drained or waterlogged conditions. Incorporating organic matter, such as compost, can improve soil structure and drainage, especially in heavy or clayey soils.
Watering Needs
During its establishment phase, Japanese Cheesewood requires regular watering to support root development. Once mature, the plant becomes highly drought-tolerant, capable of surviving with minimal supplemental irrigation. However, for the most attractive and healthy appearance, it benefits from consistent moisture, especially during dry periods or extreme heat. It is advisable to allow the soil to dry slightly between waterings to prevent overwatering, which can lead to root issues.
Temperature and Humidity
Japanese Cheesewood tolerates heat and humidity well, making it suitable for warmer climates. While robust, it is sensitive to prolonged freezing temperatures, which can cause leaf damage. Established plants withstand temperatures down to approximately 10°F (-12.2°C) in USDA Zone 8. Protecting plants from cold, drying winds helps prevent damage in marginal hardiness zones.
Pruning Techniques
Japanese Cheesewood responds well to pruning, which maintains shape, controls size, and promotes plant health. Pruning can be done at any time, but for optimal flowering, prune after flowers fade in late spring or early summer, as blooms appear on old growth. Techniques include thinning for air circulation, heading back to reduce size, and shearing for formal hedges. When pruning for size control, it is best not to remove more than a third of the foliage at once to avoid stressing the plant.
Fertilization
While Japanese Cheesewood is not a heavy feeder, applying a balanced, slow-release fertilizer in early spring can promote optimal growth. A granular fertilizer with an N-P-K ratio such as 10-10-10 or one slightly higher in nitrogen, like 10-6-4, can be effective. Following the manufacturer’s instructions for application rates is important to avoid over-fertilization, which can lead to leggy growth. Established plants in good soil may require less frequent fertilization.
Common Landscape Applications
Japanese Cheesewood is a versatile shrub used in various landscape designs. Its dense, evergreen foliage makes it an excellent choice for privacy screens and hedges, offering year-round visual barriers. The shrub’s mounding or broad-spreading habit also suits foundation plantings, providing a solid green backdrop.
Beyond mass plantings, Pittosporum tobira can serve as a striking specimen plant, especially when allowed to grow into a multi-stemmed small tree by removing lower branches. Its salt spray tolerance makes it popular for coastal gardens. Dwarf cultivars are well-suited for container growing on patios or in smaller spaces.
Troubleshooting and Common Issues
While Japanese Cheesewood is generally resilient, it can encounter certain issues. Root rot is a common problem, primarily caused by poorly drained or waterlogged soil. Symptoms include yellowing foliage, wilting, and a general decline in plant vigor. Ensuring proper drainage and avoiding overwatering are the most effective preventive measures.
The shrub can also be susceptible to pests like aphids, mealybugs, and scale insects. Aphids cause distorted growth and sticky honeydew, while scale insects appear as small bumps on stems and leaves, weakening the plant. Leaf spot diseases, such as those caused by Cercospora fungi, may manifest as small, angular yellowish-to-brownish spots on leaves, potentially leading to premature leaf drop. Maintaining good air circulation, avoiding overhead watering, and promptly removing infected plant debris can help manage these issues.