Vegetation
Management

Shinjuku Gyoen has been open to the public for over a century. As the garden’s trees grow older and larger, issues are emerging that affect use of the area in and around the garden. These include increased leaf litter, reduced sunlight and visual obstruction by dense foliage, and the risk of decay leading to falling branches or trees. Consequently, we are working to cultivate healthy trees at Shinjuku Gyoen to ensure park safety, eliminate outbreaks of disease or pests, and improve the garden landscapes.

Ensuring safety by removing leaning trees and clearing overhanging branches
Eliminating outbreaks of disease or pests by removing or replacing aging trees and plants
Preventing accidents by cutting down trees infected by wood-decay fungi or diagnosed as hazardous
Improving landscapes and usability by maintaining sightlines through landscaping and pruning
Carrying Out Garden Management Work

1．Ensuring safety by removing leaning trees and overhanging branches

Entry restrictions or path closures are put in place as soon as a tree or plant is identified as hazardous. This is followed by a sequence of safety steps to ensure safety.

Illustration of hazardous trees and countermeasures. Examples include leaning trees with uplifted roots and hanging broken branches. These pose risks of falling or dropping branches if left unaddressed. Areas with fallen or broken trees will be closed to the public.

2．Eliminating outbreaks of disease or pests by removing or replacing aging trees and plants

Trees infested with disease or pests are cut down or burned. Tree damage from oak wilt caused by oak ambrosia beetles was found in 2019, and damage caused by red-necked longhorn beetles was found in 2025. Therefore, we are working to properly dispose of damaged trees alongside cutting down weakened trees as a precaution.

Illustration of pest and disease-infected trees and countermeasures. Examples include trees infested with bark beetles or powdery mildew. These pests and pathogens hinder healthy growth, leading to withering or breaking. If untreated, the damage may spread to surrounding trees.

3．Preventing accidents by cutting down trees diagnosed as hazardous

Even trees that appear healthy can become weakened in a short time from colonization by wood-decay fungi. Weakened trunks and branches can break when subjected to strong winds, heavy rain, typhoons, or similar events, potentially causing significant damage. We strive to prevent accidents at Shinjuku Gyoen by cutting down trees either affected by wood-decay fungi or determined to be hazardous.

Illustration of wood-decay fungi (mushrooms) on trees and countermeasures. Examples include trees with Ganoderma lucidum (reishi) or similar fungi. Decay makes the trunk hollow and fragile, increasing the risk of falling. Leaving them unaddressed raises the danger of accidents during natural disasters.

4．Improving landscapes and usability by maintaining sightlines and carrying out landscaping and pruning

We are working to restore sightlines through measures such as removing overgrown trees and switching tree species within the garden.
For details on sightlines, please see here.

Introduction to landscape improvement work. Shows thinning and pruning of trees that obstruct views. Regular maintenance ensures depth, openness, and clear vistas throughout the garden.

At Shinjuku Gyoen, overcrowded groups of trees are thinned, pruned, and weeded. Such work ultimately improves the garden environment.

Introduction to path maintenance for better visibility. Shows thinning and weeding of overgrown, dark forested paths. Periodic vegetation management is performed to keep the pathways bright and safe with clear visibility.

5．Carrying Out Garden Management Work

Large-scale work is scheduled on days when the garden is closed. However, areas deemed hazardous due to the effects of strong winds, heavy rain, typhoons, or similar events, or areas where heavy machinery or similar equipment is in use may be blocked from public access even during opening hours.

While staff patrol these areas as a precaution against incidents, safety cones will be placed in the vicinity of overhanging branches as a simple warning measure, even if the branches are unlikely to fall. We ask that you do not linger in these areas, and when passing through, make sure not to walk directly underneath any branches marked with cones.

We apologize for any inconvenience this may cause and thank you for your understanding and cooperation.

VegetationManagement