The trident maple, also known as acer buergeran, is a deciduous tree suitable for USDA zones 5 through 8. This slow growing tree requires a sunny location and well-draining soil, although it will tolerate dryness and poor soil. The trident maple grows to 25 to 35 feet with a width of 20 to 30 feet. It is upright in nature and has a spreading crown. The trident maple is native to China and is a popular tree for bonsai.
The leaves of the trident maple are three lobed with a width of 1.5 to 3.5 inches. New leaves are often bronze or purple and turn to green. In the fall, it turns majestic shades of red, yellow, and orange, and the fall colors last longer than most other maple trees before dropping. As the tree ages, the bark peels off, revealing shades of gray, orange, or brown in the trunk. The flowers of this tree are small, bright yellow, and showy in the spring. They have small red fruits, but these do not attract wildlife.
Left to its own devices, the trident maple will develop multiple small trunks. Judicious pruning of the new growth will help the tree form a single trunk with branches high enough off the ground to allow passage under the canopy. Pruning is required to help the tree develop a strong structure. The branches and trunks have thorns.
You should plant trident maples in full sun or partial shade in well-draining acidic soil. This tree is tolerant of salt, drought, air pollution, and wind. It does well in urban areas. Transplanting this tree is fairly simple as it has shallow root systems. It is a "clean" tree in that it does not drop messy leaves, fruit, or flowers. There are no known problems with pests or diseases.
The trident maple is a popular subject of bonsai, especially for beginners, because it responds quickly and easily to the bonsai training. It can be started from seed, cuttings, or air layering, all of which are easily accomplished. Keep your trident maple bonsai out of cold drafts and protect it from frost.
Because the trident maple grows quickly as bonsai, it is important to start training early by wiring and pruning in the early spring. Do not wire it too tightly as the rapid growth rate will result in wire wounds if you do.
If your trident maple bonsai is exposed to winter weather, it will lose its leaves. Don't despair. The trunk and branches alone make for an interesting display until new growth appears. You can prune off new low growth to achieve a single trunk, or leave the new growth for an interesting multi-trunked tree.
Make sure your trident maple bonsai gets plenty of sun and keep the soil moist. Repot every one to two years or as needed.