RBC Blue Water Roof Garden

Royal Bank of Canada partners with Olympic Park designer Nigel Dunnett and The Landscape Agency to present the “RBC Blue Water Roof Garden” at the 2013 RHS Chelsea Flower Show (21 - 25 May 2013).

The garden is in keeping with the goals of RBC Blue Water Project - a wide-ranging, 10-year global commitment to help protect the world’s most precious natural resource: fresh water.

The design of the RBC Blue Water Roof Garden addresses two important issues – the need for effective urban water management, and for more green spaces in built-up areas. The garden is a creative solution that brings trees, meadows and wetlands into the heart of the densest of cities, while promoting water-sensitive design. It is the first example at RHS Chelsea of a full ‘living roof’, which aims to encourage wildlife and habitat biodiversity along with sustainable water management, in an urban rooftop setting.

Nigel Dunnett, Lead Designer on the project, commented: “With limited space available on street-level, urban planners really need to look skywards for the green spaces that will allow people in cities like London to maximise their contact with nature. We have extended the water preservation themes explored in our previous Chelsea gardens, and turned our attention to creating a ‘living roof’ that is able to collect and filter rainwater allowing vegetation to flourish atop sky rise buildings all year round.”

Filled with flower-rich planting, the RBC Blue Water Roof Garden features a central wetland that harvests and circulates rainwater runoff to irrigate the garden. Trees envelop the garden, with a low-tech, low-irrigation living wall of drought-tolerant succulents grown in stacked terracotta units used to separate the space from adjacent rooftops.

The materials and choice of flowers – many of which originate from RBC’s native Canada - have been carefully selected to attract and foster local wildlife, while seating areas flow seamlessly into the varied landform.

A winding boardwalk leads to a dramatic ‘bird hide’ structure clad in habitat panels, from which the biodiverse surroundings can be observed uninterrupted. The rooftop ‘furniture’ of vents, chimneys and air conditioning units become habitat and design features in themselves.

Plant list

Zone 1:
Shade/woodland underplanting. Rich and diverse underplanting, loosely based on the groundmflora of woodlands of Eastern North America.
• Aquilegia canadensis
• Trillium grandiflora
• Mertensia virginica
• Phlox divaricatus
•Tiarella ‘Spring symphony’
• Tiarella wherryi

Zone 2:
Sunny edges/green roof planting. Plants for free-draining soils in sun. A mosaic of bright
colours and grasses.
• Allium schoenoprasum
• Dianthus carthusianorum
• Erysimum ‘Bowles Mauve’
• Festuca amythestina
• Geum triflorum
• Gypsophila repens ‘Rosea’
• Helictotrichon sempervirens
• Melica altissima alba
• Salvia ‘Maynight’
• Sedum rupestre ‘Blue Spruce’
• Sedum rupestre ‘Lemon Ball’
• Sesleria nitida
• Silene armeria ‘Electra’
• Silene uniflora
• Stachys byzantina
• Verbascum phoenecium ‘Violetta’
• Centaurea cyanus
• Chrysanthemum segetum hybrids
• Dimorphoteca aurantiaca
• Atriplex hortensis rubra

Zone 3:
Wetland Marginal. A mass of blue Meconopsis with textural and foliage plants.
• Deschampsia flexuosa
• Dryopteris lepidopoda
• Hosta ‘Tom Schmid’
• Lychnis flos-cuculi
• Lychnis flos-cuculi ‘Alba’
• Matteucia struthiopteris
• Meconopsis ‘Lingholm’
• Osmunda regalis
• Primula x bulleysiana
• Valeriana officinalis

Zone 4:
Aquatics. Dramatic foliage plants emerging from the water.
• Cyperus eragrostis
• Equisetum japonicum
• Juncus effusus
• Phragmites variegatus
• Scirpus cernuus
• Thalia dealbata

Trees:
• Betula papyrifera
• Cornus florida
• Cornus florida ‘Cherokee’