Nature Takes Over a Metro Station – Meadow Calls Pollinators to the Roof in Helsinki

A pollinator roof will bring a meadow, wildflowers, and bumblebee nests to the metro station. A bus stop made from recycled glulam from construction sites will pilot how recycled material functions as a rain shelter for those waiting for the bus. A green wall outside the metro station will create a vertical green surface. This experiment will pilot the use of a sprayable growing medium and a seed mix suitable for Finnish conditions, as well as identify which plant species thrive there.

All three pilots focus on ecological sustainability and biodiversity. If the solutions prove successful, they could become more common in cities.

“We want to continue building urban transport in a way that considers and supports nature, its biodiversity, and pleasant urban spaces, so we are happy to be involved in developing new types of green solutions,” comments Leo Hakkarainen, Lifecycle Specialist at City Transport.

City Transport is involved in the experiments, which are coordinated by the PilotGreen project, funded by the European Union and led by Forum Virium Helsinki, the City of Helsinki’s innovation company, focusing on urban greenery.

Pollinator Roof for the Metro Station

This summer, the roof of the Herttoniemi metro station entrance will feature a meadow, wildflowers, and bumblebee nests. The 30-square-meter meadow area will provide food and a resting place for pollinating insects in the neighborhood. Pollinators will visit and buzz around on the roof but pose no danger to those using the entrance.

“Bumblebees are peaceful creatures that fly about their business from the roof to the flowers and back, and they have no reason to sting passersby,” assures Aapo Reuter from HumbleBee Housing Project.

The Herttoniemi experiment is being carried out by Blokgarden and HumbleBee Housing Project. A similar meadow solution was successfully trialed last summer on the canopy of Sokos in Tampere.

Pollen collected by bumblebees will provide information about the biodiversity of the surrounding nature through eDNA analysis. This information can then be used to select plants specifically suited for the pollinators in the area.

Bus Stop Made from Demolition Site Glulam

Currently, there is no rain shelter for those waiting for the bus on the Hertta side of the metro station, but one will be provided now. The stop will be made from glulam from demolition sites, which will also allow testing how the recycled material performs in structures.

The roof of the stop will also have plantings for the summer. The slanted shape of the roof directs rainwater into the structure, acting as a passive irrigation system. Spolia Design is responsible for this experiment.

Green Wall on the Metro Station Facade

The third experiment will be on the outer wall of the metro station entrance. A growing medium mixture containing seeds will be sprayed onto a pre-constructed, multi-layered structure in early summer. The goal is for the wall to be covered in plants over the summer.

This experiment will identify suitable species for green walls, develop a growing medium mixture, and investigate the possibilities of using recycled materials in the green wall element and growing medium mixture. Rakennusbetoni- ja Elementti Oy and Sitowise Oy are behind this experiment.

The Herttoniemi experiments are being implemented as part of the PilotGreen project, which focuses on innovative green solutions, is co-funded by the European Union, and coordinated by the innovation company Forum Virium Helsinki, in cooperation with Kaupunkiliikenne Oy. In total, PilotGreen will bring seven different experiments to Helsinki in the summer of 2025.

Photo: Vesa Laitinen