The Coral Bark Maple, also known as Acer palmatum ‘Sango-kaku’, is a cultivar of the Japanese maple featuring a striking coral-red bark. This deciduous tree is native to Japan, Korea, and parts of Russia and Mongolia. It is particularly loved by many for its four-season interest in the landscape, with the bark color being especially prominent in the winter months after the leaves have dropped.
The Coral Bark Maple cultivar was introduced to the horticultural world in the early 20th century, around 1920. The name ‘Sango-kaku’ translates to “coral tower” or “coral pillar,” a fitting description for the tree’s upright growth habit and the coral color of its bark.
The Coral Bark Maple is known for its four-season interest in the landscape, with the vibrant bark color being especially prominent in the winter months. It reaches a mature height of 15 to 20 feet and a spread of 15 to 20 feet. The tree is generally a low-maintenance requiring little pruning and being tolerant of a range of soil types including sand and heavy clay.
Characteristics of Coral Bark Maple
- Size and Growth Rate: It reaches a mature height of 15 to 20 feet and a spread of 15 to 20 feet. It is a slow- to moderate-growing tree, typically adding about 12-24 inches of height per year.
- Growth Habit: This tree has an upright and vase-shaped growth habit, with a height and spread of 5 to 15 feet at maturity.
- Bark: The bark has a coral-red color, especially prominent in winter after the leaves have dropped. The color intensifies in cold weather and is deeper the more sun the tree receives.
- Leaves: The leaves emerge in spring in a bright, lime green or chartreuse color. They then mature to a deeper green in summer before transitioning to a golden yellow and orange in the fall.
- Flowers: Produces small, inconspicuous flowers in spring, but they are not the main attraction of the tree.
- USDA Zones: This tree is hardy to zones 5-8 according to the USDA Hardiness Zone Map.
- Root System: The root system is relatively shallow and non-invasive. This maple can be planted near structures and paved areas.
- Lifespan: With proper care can live for 50 to 150 years.
- Light Tolerance: Prefer full sun to partial shade. The sun brings out the red color in the bark, much like it does in red leafed Japanese maples.
- Temperature and Humidity: It is tolerant of a wide range of temperatures and humidity levels. It does well in areas with moderate to high humidity.
- Toxicity: It is not known to be toxic to humans, pets, or wildlife.
- Water: Prefers moist, well-draining soil. It requires regular watering, especially during the first two weeks after planting. After the second week, watering can be reduced to once or twice a week.
- Soil: This tree can tolerate a range of soil types, including sand and heavy clay, as long as the soil is well-draining.
- Propagation: Can be propagated by seed, grafting, or cuttings. Seed propagation is challenging and takes a long time. Grafting and cuttings require some skill but are more successful methods.
Problem associated with growing Coral Bark Maple
- Leaf Scorch: This occurs when the leaves become brown or wilted due to excessive sunlight, heat, or wind. It can be mitigated by planting the tree in a location that provides some shade during the hottest part of the day.
- Powdery Mildew: This fungal infection appears as a white, powdery coating on the leaves and stems of the tree. It thrives in humid, shady conditions and can weaken the tree over time if left untreated. Regular inspection and treatment with a fungicide can help manage this issue.
- Aphids and Scales: These are common pests that can suck sap from the leaves, causing discoloration, stunted growth, and honeydew buildup (which attracts other insects). Insecticidal soap or neem oil spray can be effective solutions.
- Iron Chlorosis: This condition, also known as yellowing leaves, can occur in alkaline soil. The leaves turn yellow while the veins remain green. Iron supplements or chelated iron products can address this.
- Physical Damage: Lightning strikes, severe winds, animal damage, and even climbing children can damage the trunk and branches of the tree.
- Winter Burn: In harsh winters, especially with strong winds and cold temperatures, exposed branches might experience winter burn, causing leaf damage. Protecting the tree with burlap can help in some cases.
- Coral Bark Canker: This disease causes the bark to turn a distinctive coral color, indicating that the fungus has attacked the vascular system of the tree, obstructing the flow of water and nutrients.
- Root System Issues: The Coral Bark Maple has a relatively shallow and non-invasive root system, which can be planted near structures and paved areas. However, improper planting depth or soil conditions can lead to root-related problems.