Planting as an art form: ecologically-tuned, aesthetically aware. Planting as an essential: creating healthy cities and liveable places
Project Title: London Wetland Centre Rain Garden Date of Completion: September 2010 Design: Nigel Dunnett with The Landscape Agency
Project File: The Royal Bank of Canada Rain Garden at the London Wetland Centre
For plans, planting lists, and technical details, click here The London Wetland Centre Rain Garden was opened in September 2010, as part of the celebrations for the 10th anniversary of this important nature site in West London, owned by the Wildfowl and Wetlands Trust. The London Wetland Centre was created on the site of former reservoirs and water treatment works, and is visited by tens of thousands of school children every year, together with thousands of families and individuals who come to learn about wetland wildlife and to enjoy the beautiful landscape and extensive visitor facilities. The Rain Gardens forms part of a series of 'Sustainable Gardens' on site, designed by invited designers. The brief for the garden was very clear: to provide an interactive and very attractive garden that would demonstrate the importance of water conservation, and which would inspire people to try out water-saving and rain garden techniques themselves at home. Unlike other existing garden areas at the Wetland Centre, the intention was that the garden was fully accessible to visitors so that people could investigate and see how things worked: as a result the construction, materials and planting had to be very robust. to themselves: ‘that’s fantastic - I can do that at home!’ The garden space has dimensions of 20 metres x 20 metres , and has an existing small stream running through the middle: the land rises gently on each side of the stream by around 3 feet to create a very slight valley landform. The layout of the garden is loosely based on a series of concentric circles, suggesting radiating ripples created by rainfall on a pool. A widely curving boardwalk brings people through the garden and is accessible to all. In addition there are many small exploratory paths. Stepping stones enable brave people to cross the stream: it was very important to give as much interaction with water as possible, to counter the pervasive view that open water in the landscape is a danger. A level, sweeping board walk path (made from recycled timber-effect plastic) takes visitors all around that garden and over the stream, providing access for all A more direct path leads visitors to the garden building, via 'stepping stones' across the stream, which periodically become covered with a thin layer of water when the stream level rises
At the heart of the garden is a series of circular raised beds which lead off from a small garden building that acts as a shelter and information point. The beds, which step down a gentle slope, soak up water which is passed along a series of wooden rills. Each mini-garden absorbs some of the water into the soil, but much of it is drawn up and transpired by the planting, sending it straight back into the atmosphere. Any excess runoff overflows and moves onto the next bed. The planting in each bed is slightly different, responding to the decreasing moisture gradient that is produced. One of the beds is water rather than soil filled and planted with true aquatics (which have a water-cleansing function), whilst the rest employ moisture tolerant species, carefully chosen to survive the wide ranging conditions they will experience, which can include extended periods of drought.
Ultimately little if any water is left to pass into the stream. Consequently a treadle pump has been installed to lift water up from the stream, allowing it to fall back down the lower rills. Working the pump engages visitors in a physical activity and demonstrates what would otherwise be rather a subtle effect – as in normal conditions no rainwater should appear at the lower end. The intention with the pump is to show visitors exactly how rain gardens work: a case of making the water cycle visible. The garden in spring 2011, showing the circular rain garden areas
The garden in August 2011 The focus of the garden is the building that collects rainwater and supplies it to the garden. The ‘Rain Shelter’ is a converted shipping container with a diverse green roof. The container had a previous life, moving cargo around the world, and is a prime example of recycling and re-use of materials: a concept underpinning the use of materials throughout the whole garden: while building the garden it became a matter of principle to source reclaimed materials wherever possible; this not only helped stretch the budget, but also produced a highly individual garden and one from which people leave inspired by ideas which they can easily employ at home. This can perhaps best be seen in the constructions of the walls around the rain garden areas, but also in the dramatic and imposing ‘creature towers’ that rise up from the wildflower meadows that fill the garden. These are multi-story habitat and feeding sculptures that have the potential to attract a wide range of life. The planting throughout the garden is naturalistic and meadow-like in character. The garden building, designed by John Little and Green Roof Shelters, features a biodiverse green roof and habitat panels in the wall Garden Planting Brief details of the garden planting are given below.
A captioned photoset showing details of the planting can be found here The full plant list, planting typology and plant numbers can be found here
The garden planting consists of a number of mixes of perennials that are related to different zones and conditions within the garden. Instead of having a hedge or fence along the edges of the garden, a sunken bioswale prevents people entering unless on the main paths (functioning in the same way as a 'haha in landscape gardens) and also collects water from the surrounding hard surfaces. The 'bioswale hahas' are planted with Himalayan Cowslips, Marsh Marigold, Flag Iris, Day Lilies, Purple Loosetrife and Wood Geranium.
'HaHa Bioswale' Planting Wetland marginal plants alongside the stream include Ligularia stenophylla 'The Rocket', Marsh Marigold, Purple Loosetrife
Ornamental perennial plantings include naturalistic mixtures with Calamagrostis x acutiflora 'Karl Foerster', Aster x frikartill 'Moench', Kniphofia 'Tawney King', and Gaura lindheimeri. Mixed naturalistic perennial plantings
The circular rain garden areas include Rudbeckia fulgida 'deamii', Astilbes, Rodgersia and Primula pulverulenta. Rudbeckia fulgida 'deamii' in one of the circular rain gardens Creature Towers are sculptural biodiversity structures
The Rain Garden has been an outstanding success: people are drawn: the combination of wildlife-friendly features, colourful planting, the curving arc of the linked rain gardens, and the striking nature of the green-roofed building produce an impression that is quite different from the normal garden experience. ‘From day one, the garden has been full of children and adults enjoying the interaction with water and nature, and they all come away knowing what rain gardens are all about. That’s exactly what we wanted’, says Simon Rose, the Developments Manager for the Wildfowl and Wetlands Trust.