Vertical plantings make green spaces greener

Perennials are increasingly being used in vertical plantings. We’re seeing more and more of these living walls full of perennials appearing in our streetscapes. Keeping a number of their requirements in mind, many kinds of perennials are suitable for this purpose. Densely developed parts of the city are particularly good locations, since these plantings can contribute to a healthy living environment there. From providing natural air-conditioning to reducing noise.

 

The benefits of vertical plantings using perennials go a lot further than just their aesthetic effect that attracts the attention of passers-by and lifts their spirits:

1. The release of water vapour from their leaves has a cooling effect.
2. Since these living walls warm up more slowly during the day, they release less heat at night.
3. Their leaves improve air quality by absorbing CO2 and pollutants in the air such as soot, particulate matter and nitrogen oxides.
4. Walls covered in plants absorb 2.5 to 3 decibels of sound, so they reduce street noise.
5. And they also enhance biodiversity.

A beautiful finished look straightaway
The structure of a vertical planting using perennials consists of facade panels for holding growing medium and also an irrigation system for watering and fertilising. New systems making use of new materials and techniques are frequently becoming available. The wall is densely planted so that little if any of the supporting structure is visible. This provides a beautiful finished look as soon as the installation is complete.

Sun and shade
Many kinds of perennials can be used to cover living walls. The choice depends on their growth habit and the number of hours of sun they will receive. Good choices for a sunny wall would include Bugleweed (Ajuga reptans), Cranesbill (Geranium), Lamb’s Ear (Stachys byzantina) and Fountain Grass (Pennisetum ‘Hameln’). Deer Fern (Blechnum spicant), Elephant-eared Saxifrage (Bergenia), Lungwort (Pulmonaria) and Coral Bells (Heuchera) are just a few of the perennials useful for a shady wall.

The facts Installing living walls requires professional expertise. Since they have to be checked weekly, green walls supported by facade panels are not exactly low-maintenance. Nevertheless, their advantages for public green spaces more than outweigh their costs.

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Horticulture as catalyst for green cities

What does the green city of the future look like? It’s an upcoming theme in cities worldwide, says Dutch landscape architect Niek Roozen: “The Green City is a concept which is coming up everywhere, whether we’re discussing the green structure of new districts in Shenyang, the upcoming Horti Expo in Beijing or the Floriade 2022 which will be hosted in Almere. It’s clear that countries are investing more energy in making their cities greener.”

As a landscape architect, Niek is involved with horticultural projects all over the world. But China particularly appeals to him. Besides his office in Weesp (NL), his firm can also be found in Shenyang (CH). “In the Netherlands, we often think Chinese cities are only filled with large concrete flats and buildings. However, when you take a closer look you’ll see beautiful cities which invested heavilly in their green structure.” Niek is currently working on the project ‘Colourful Beijing’ of the local Beijing government. This project aims to make the city more livable and colourful at all times of the year through horticultural projects. Examples are adding evergreen conifers or shrubs with berries and early blooming plants.”

Niek’s Green City concept resonates. He’s been involved with over a dozen Floriades, Horti Expo’s and World Expo’s, from Vietnam and Qatar to the Netherlands and China. The Ministry of Agriculture in the Netherlands invited him to design the Dutch entry for the Beijing Horti Expo, which will open in April. “Green Cities will also be an important theme here. In the Dutch garden we aim to show the diversity of the Dutch horticultural sector. On the one hand we’re showing the diversity of plants and making cities more livable and colourful. On the other hand we are showcasing themes such as sponge cities and sustainable food security.

As such, Niek is creating an inspiring Green City-setting at this years’ Horti Expo. The Dutch garden will symbolize a city, with steel constructions as the skyline, combined with gardens and trees. Miniature pavilions will offer room for organisations working on greening cities and sustainable food to showcase themselves. The Ministry of Agriculture, Wageningen University and the Floriade 2022 will all be hosting a pavilion as well. Also, there will be activities to translate the concept of green cities to children. Two Holland-pavilions will be manned by students of the Aeres University of Applied Sciences, who will also carry out research in the area of Beijing.

Of course, also the Dutch partiality to biodiversity will be showcased in the different gardens. Flowers which appeal to butterflies or bees, but also plants you often find in your own kitchen at home. The borders surrounding will be like a colourful bouquet according to Niek: “We’ve planted over 10.000 tulips here, which will be in full bloom during the opening in April. To ensure the garden remains colourful we will plant additional flowers twice, adding for instance alliums or dahlias.”