Trident Maple Forest Care Guide

We recommend you also read our Trident Maple Care Guide!

General Information:

Forest plantings require species that are somewhat upright growing, as well as those that can tolerate a shallow root system. Trident Maple, or Acer buergerianum, is a perfect choice. This deciduous native of Japan, China, and Korea may grow to 20-30 feet in its natural habitat and may be identified by its three-lobed leaves (as opposed to Acer palmatum which has five-lobed foliage).

Tridents makes a beautiful 5, 7, or 9 tree forest both for its stunning fall color and ease of care.

Tree's Attributes:

While the Trident Maple does have a fairly thick trunk, it is also straight and consistent which makes it a great choice for a forest. The leaves are small for a maple – up to three inches wide – which will allow the grouping to look proportionate. The root system typically develops surface gnarls, which can add visual interest to a 7 tree planting. The red, orange, and yellow colors of the leaves in fall lend a striking point of interest to this group.


Trident Maples are hardy trees, and particularly with a group planting should be kept outside. This bonsai needs to experience dormancy, whether alone or in a 7 tree forest planting. The roots are moisture-rich and need to be insulated in winter. This is especially important in a forest bonsai because of the shallowness of the root system required, they will be more vulnerable to freezing temperatures.

The forest should be exposed to full sun, and the container will need to be turned every so often so that all of the trees get enough sunlight.


Water the Trident Maple forest as you would your normal Trident Maple bonsai – the soil should be kept moist but not over-saturated. In the hottest parts of summer, the planting may need more frequent watering than normal, and in winter, the soil should be kept a bit dryer than usual due to the risk of freeze damage to the roots. Be sure to check the soil around each individual tree in the 7 tree group, not just in one spot as the moisture level could be uneven across the larger area of the pot.


Feed your Trident Maple 7 tree forest every week during the growing season and every other week throughout summer and early fall. Once summer is over, change from a balanced formula to a low nitrogen, high phosphorus fertilizer. Take extra care to be sure that the roots of all the bonsai in your grouping receive adequate fertilizer.


Pruning a forest planting requires thoughtful planning and observation of how each tree's placement and branch structure affects the other trees.

Shoots that grow downward and branches that are crossing each other should be removed. The crowns should be pruned so that the branches at the tops of the trees are the shortest, and they become progressively longer as they move down the trunk.

Congested areas of foliage can be trimmed. The trees in your Trident Maple 7 tree forest can be wired if needed to redirect an awkward branch, just be sure to do it gently as the branches are brittle.


Bonsai forest plantings may be propagated just like any other tree in their particular species. In the case of Trident Maples, they may be propagated by seeds, layering, or softwood cuttings.


Normally a Trident Maple would need repotting every one to three years, depending upon its age. The time intervals for repotting a forest planting are the same; the only exception is that you want to be sure that the group has been in the container for at least two years before repotting for the first time, because the roots need time to intertwine. You don't want the composition to come undone when removing the trees for transplanting.

Once you've removed the trees from your Trident Maple forest, remove the old soil from the root ball's edges, cutting into the root system in wedges as you do so. Be very careful to ensure that each tree retains enough of its own root system to support itself. The soil in the center of the grouping becomes compacted over time and must be coaxed loose very gently with a stick or a stream of water, then replaced with new soil.

Insects/Pests & Diseases:

Fortunately, this species is pest and disease resistant, so there isn't much worry of disease passing from tree to tree. Aphids or caterpillars may sometimes attack, but can be removed easily – caterpillars manually, aphids with either a stream of water or a spray solution of one teaspoon dish liquid and a quart of water. Rinse with plain water after this soapy bath. Root rot may affect maples, so take extra care to monitor the moisture level of the soil around the entire planting to ensure that no localized area becomes boggy.

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