Nikko maple is a small tree with lovely yellow and orange fall foliage. Its stunning red branches add interest to the winter landscape. This tree is an excellent choice for any landscape looking for a pop of color.
I. Appearance and Characteristics
Acer maximowiczianum (Nikko maple; syn. A. nikoense Maxim.), is a species of maple widely distributed in China (Anhui, Hubei, Hunan, Jiangxi, Sichuan, Zhejiang) and Japan (Honshū, Kyūshū, Shikoku).
It is a slender deciduous tree that reaches a height of 15–20 m (49–66 ft) but is usually smaller. It is a trifoliate maple, related to such other species as threeflower maple (Acer triflorum) and paperbark maple (Acer griseum) but has dark gray to blackish bark dissimilar to the exfoliating bark of either.
The leaves have a 3–5 centimeters (1.2–2.0 in) petiole and three leaflets; the leaflets are oblong, 5–15 centimeters (2.0–5.9 in) long and 3–6 centimeters (1.2–2.4 in) broad, with dense, soft pubescence and smooth margins. The hard, horizontally spreading samaras are 3.5–6 centimeters (1.4–2.4 in) long and 1.2 centimeters (0.47 in) broad, and have the same parthenocarpic tendencies as those of A. griseum.
Nikko maple was first introduced to cultivation in 1881, when seeds were imported by the Veitch Nurseries in England, after they were discovered by Charles Maries in the forests of Hokkaidō. It is rarely seen in cultivation outside of arboreta. The largest specimens in England are up to 17 meters (56 ft) tall and 70 centimeters (28 in) trunk diameter. In the United States, a mature specimen may be seen at Arnold Arboretum in Boston, Massachusetts.
II. How to Grow and Care
Sunlight
Nikko maple thrives in conditions of partial sun, where it receives ample light without the intensity of full midday rays. This ensures a balance of brightness and protection during the hottest part of the day. However, nikko maple is also quite adaptable to full shade, displaying resilience when sunlight is diffused or indirect, such as under a canopy of taller trees. In suboptimal light, nikko maple may exhibit slower growth rates and less vibrant foliage. While grown outdoors, nikko maple is best positioned in a garden spot that mimics its native woodland habitat — dappled light is ideal. Leaf pigmentation could vary according to light levels, serving as a natural indicator of the plant’s light exposure and health.
Temperature
The nikko maple has good cold resistance and is able to tolerate low temperatures. The nikko maple is native to the margins of forests in China, Japan, and North Korea, so these trees generally prefer a humid environment. Most nikko maple plants have shallow root systems, so they should be watered frequently during the summer. For some varieties, a sprayed mist should be provided during the summer to increase the humidity of the air around them.
Watering
Thriving in its native forested regions, nikko maple is accustomed to consistent moisture levels and demonstrates a moderate tolerance for drought. Ideally, this species prefers a balance of well-drained soil and ambient humidity, aligning with its natural habitat’s conditions. Watering should occur once every two weeks to maintain optimal hydration without over-saturating the roots. As an outdoor deciduous plant, nikko maple’s water needs fluctuate with the seasons, requiring less frequent watering during its dormancy period in colder months.
Soil
The nikko maple does not have many specific requirements for soil. It is a forest native, so it prefers well-drained soil that is rich in humus and slightly acidic. Its main root will extend deep into the soil, but its tiny fibrous roots will be concentrated near the soil surface, so accumulated water in the soil tends to cause root rot.
Fertilizing
Potted seedlings should be given slow-release fertilizer only. For seedlings grown in gardens, fertilizer should be applied three times a year: once in the early spring, once in early summer for the growth period, and once in the fall.
Planting Instructions
The best time for planting or transplanting a nikko maple is following defoliation in the fall. At this time, the leaves will have fallen off so there is little transpiration and water loss can be avoided. In addition, the root system will still be growing at this time, preparing for regrowth the following spring. Transplanting should be avoided on the coldest days because cold wind can kill some of the shoots and branches. During the winter, in areas that cannot be sheltered from the wind, it is recommended to cover the branches.
Pruning
Pruning is mainly used to enhance internal ventilation, improve shoot formation, promote growth, and for shaping. The common approach to pruning is to remove any old or weak branches, remove any branches that disrupt the shape of the tree, and remove any branches that cross other branches. Pruning is used to control the plant according to the required height and shape. Generally, this follows the “Y-type” pruning method.
It is possible to prune a nikko maple throughout the year, but the coldest winter months should be avoided to prevent damage to the plant. Major pruning to shape a maple can be performed following defoliation in the fall, or prior to leaf growth in the spring. It is recommended to prune in the fall because withered and full buds can be easily distinguished.
According to the shaping plan, you can prune any withered buds and keep the full ones, thus making your tree healthier. For pruning in the summer, diseased, weak, or dead branches can be removed, mainly to enhance the tree’s ventilation.
If grown as a potted plant, the roots can easily occupy the entire flowerpot due to the limited space. This can make a nikko maple prone to aging if an old flowerpot is not changed. It is recommended that old roots are pruned during the dormancy period, that is, cut off any old, coarse, diseased, and weak roots.
Propagation
A deciduous tree known for its attractive foliage, nikko maple benefits from propagation techniques tailored to its specific growth habits. Cutting, an effective method for this species, involves taking healthy semi-hardwood segments during active growth. Ensuring a sterile environment and using rooting hormones can enhance success rates. Once cuttings are prepared, they should be placed in a well-draining medium and kept consistently moist. Root development is critical before transplanting to a more permanent location for maturation.
Transplanting
For nikko maple, the prime time for replanting is between late spring to early summer, when conditions foster optimal root establishment. Choose a location with well-draining soil that gets partial shade. Ensure the soil is moist and enrich it with organic matter to give nikko maple a strong start. A friendly tip: don’t forget to keep the root ball intact during the move for a smooth transition!