The Barbican, London.
Planting Design & Lead Designer: Nigel Dunnett; Construction Detailing, Technical Support & Graphics: The Landscape Agency; Client: City of London Corporation & The Barbican Estate Office; On-site plant arrangement and setting-out: Nigel Dunnett & Taina Suonio; Plant Supply: Palmstead Nurseries; Green Roof Buildup: ZinCo UK; Date: Phase 1: 2015
The Barbican is Europe’s largest arts and conference complex under one roof, and also includes a significant residential community of 4000 people. It is a noted example of Brutalist architecture, built mostly in the 1970s. The original design aimed to create a self-contained ‘urban village’, with the residential and public spaces separated completely from vehicle traffic. Most of the landscape elements, including the water bodies, are ‘podium landscapes’ or ‘landscapes above structure’: roof gardens and green roofs, with car parks, the arts complex, and recreational facilities beneath.
Previously, the roof gardens comprised conventional lawns, flower beds, trees and shrubs, which required continual irrigation and a high maintenance regime. In 2013, as part of an ongoing re-waterproofing of the building structure, the opportunity arose for completely new plantings to be installed. The new design takes a radically different approach. Phase 1 of the rewaterproofing project was installed in 2015 and comprises Beech Gardens and associated High Walk areas. Phase 2 is scheduled for installation in 2025 and extends the plantings into an even larger area.
Above: Allium 'Purple Sensation' in May 2024, rising up out of the grassy matrix below. With pink-flowered Eurodium manascavii and the lime-green bracts of Euphorbia characias 'Humpty Dumpty', and silvery flower spikes of the grass, Sesleria nitida
Conceptually, the planting scheme consists of three main ‘Designed Plant Communities’ that are suited to different microclimates around the site, according to how much sun different areas receive, and the depth of the growing medium that was possible. Designed plant communities are combinations or mixes of plants that are ecologically compatible with each other, and which operate with many of the characteristics and processes of natural or wild plant ecosystems:
1. 'STEPPE' plantings in full sun. In very open, sunny, exposed, windy conditions with relatively shallow depths of growing medium (200 – 300mm) I developed a designed version of ‘steppe’ grassland, using grasses and perennials that are naturally adapted to dry, stressful conditions
2. 'SHRUB STEPPE' Where the underlying structural support of the building allowed greater substrate depths, I designed a ‘shrub-steppe’ planting that combined similar mixes of dry-tolerant perennials and grasses to the steppe plantings, but with additional scattered low-density shrubs and multi-stemmed trees, to create multi-layered plantings with year-round structure and interest. These have developed into an open woodland edge character.
3. DRY WOODLAND plantings in part-shade, and where the growing medium depths enable tree growth, I used widely spaced multi-stem trees to create a light, open canopy, with a scattered understory of shrubs, and a diverse perennial ground layer, with many white flowered plants to bring light to the shade.
Above: A general section through Beech Gardens at The Barbican, showing the range of substrate or growing medium depths that were achievable, depending on the structural support of the roof below at any particular point. Substrate depths ranged from 100mm to 900mm, with typical depth being 200-300.
The landscape at The Barbican is Grade 2* listed because of its historical significance and therefore it was not possible to change the shape of the existing planting beds. A range of substrate depths was possible: in places where there is underlying structural support to the roof, the substrate depth could be increased, allowing the inclusion of trees and shrubs.
The images below are taken from the design report. The top two diagrams show the layout of the existing planting areas, in green.
The lower image shows a microclimate analysis and zonation of the site. Areas coloured orange are exposed and in full sun for much of the day. Hot in summer, cold in winter, windy for much of the time, and also coincide with the areas where only the more shallow substrate depths were possible.
The area in blue/green is sheltered and shady for much of the day, while the yellow areas are intermediate in sun and shade between these extremes. The rectangular blue area is a small lake
By combining the micro-climatic information, and the loading tolerance of the roof (and therefore the depth of the substrate that was possible in different parts of the site), a spatial planting strategy was developed.
The following sections show a photographic record of the three main planting types through the year, with most of the photos from 2024.
Steppe Plantings
The steppe plantings are the main feature of the transformation project at The Barbican, and these plantings form the basis of the other planting types too. In nature, steppes or steppe grasslands occur in dry regions with continental climates (hot dry summers, cold winters). Steppe plants are adapted to these harsh conditions. The plantings at The Barbican are not attempting to copy any naturally-occurring steppe grasslands, but are a designed version, using perennials and grasses from steppe regions or dry grasslands and meadows. A matrix of tough, drought-tolerant grasses (Sesleria nitida, Helicotrichon sempervirens, Melica ciliata) creates the backdrop to a long succession of flowering species through spring to late summer. Later in the summer, and into autumn and winter, the emphasis switches to beautiful textural contrasts as foliage and seed heads take over the display.
In late winter and early spring, the steppe plantings are full of colour with the emerging flowering stems of Euphorbia characias 'Humpty Dumpty' rising above the evergreen clumps of the grass Seslteria nitida. The cultivar 'Humpty Dumpty' is a shorter growing form of Euphorbia characias, and was used in these steppe plantings because the taller forms (which can be seen growing in the areas behind) would be vulnerable to wind damage in these very open and exposed areas. Substrate depths are also more shallow here
A scattering of Tulipa praestans 'Fusilier' in April 2024 - these are from the original planting in 2016 and still maintain a good presence, even though numbers are gradually decreasing.
In April, the grass Sesleria nitida is in full flower with white flowers that dance above foliage below. Euphorbia characias is still prominent in flower. Thyme flowering at the edge. Yellow Euphorbia polychroma is also visible
The domed, rounded forms of Euphorbia characias 'Humpty Dumpty' provide a counterpoint to the looser metrix of stress-tolerant grasses between them. The white flowers of Sesleria nitida are very visible. In the photo above, and in the one below, flowering stems of Alliums can be seen rising through.
In May and early June, the Alliums are in full flower. There are two cultivars. The earliest to flower is Allium 'Purple Sensation', above. This is followed by the shorter, but larger flowered, Allium 'Globemaster', below, mixed here with scattered Papavar orientale 'Goliath'. In the photo below, the Euphorbias are beginning to fade and ripen. Photo June 2024
Below: as the Alliums and Euphorbia start to fade, other plants begin to take over. Here, yellow flowered Sisyrinchium striatum is flowering with white Lychnis coronaria 'Alba', Sea Thrift - Armeria maritima, and pink Erodium manascavii. Photos from June 2024
Below: Blue Nepeta 'Walker's Low' with the flower spikes of the grass Melica ciliata
Below: Salvia 'Caradonna'. June 2024
Below: later in the summer the Allium seed heads dry out, and a succession of flowering plants take over. Here, Kniphofia 'Tawney King', Perovskia atricipifolia 'Blue Spire', Echinops 'Veitch's Blue' and Penstemon 'Garnet' are in full flower. The Euphorbias that were so prominent earlier in the year are now much less visible amongst the taller plants growing around them. The steppe grass Melica ciliata is flowering freely.
In late summer and autumn, Asters continue flowering. Here, the Japanese Aster, Kalimeris incisa 'Blue Star' is repeated through the steppe plantings. The dead flowering stems of the Euphorbias are cut out at the base, and the plants again become an important component of the plantings through the winter. Photos November 2024
In winter, seed heads and foliage textures dominate. The use of grasses that stay green in the winter creates a sense of vitality through the darkest months
Shrub-Steppe Plantings
Where substrate depths are deeper (300-450mm), and there is a little more shelter, shrubs as well as perennials, bulbs and grasses were possible within the courtyard areas of Beech Gardens. Similar mixes of perennials were used as with the steppe plantings, but with additional more substantial or taller species, such as Libertia formosa, Phlomis russeliana, and Miscanthus sinensis 'Undine'.
Small-medium shrubs and small multi-stem trees were used in scattered and widely-spaced arrangements to give the impression of an open shrub-steppe.
One of the key 'signature' plants is Euphorbia characias subsp. wulfenii, scattered throughout the plantings, and the evergreen plants have a very strong presence throughout the year. At The Barbican, the flowering stems start to rise in January, and the plants are in full flower from February through to May. The flower spikes ripen to orange and brown by the early summer and are cut out at the base, leaving room for the next season's shoots to expand
Below: In late winter and early spring, Euphorbia characias subsp. wulfenii is at its brightest, interspersed with clumps of the grass Sesleria nitida. The woody plants are Amelanchier lamarkii, Euonymus europaeus 'Red Cascade' and multi-stem Prunus 'Sunset Boulevard'. Photos from March 2024.
in April, the Amelanchiers and Prunus are in flower
In summer, a range of shrubs take centre-stage. The short growing Philadelphus 'Belle Etoile'' has scented white flowers. Sambucas nigra f.porfyrophylla 'Eva' has Finley dissected purple leaves and pink flowers, Cornus kousa var. chinensis has white bracts, and Hypericum x hidocteense 'Hidcote' forms evergreen mounds with yellow flowers.
In autumn, Prunus 'Sunset Boulevard' and Amelanchier lamarkii have brilliant leaf colours. Photos from November 2024
Dry Woodland
In the most sheltered part of Beech Gardens at The Barbican I created an area of dry woodland - this is surrounded on three sides by apartment blocks and is shaded for much of the day. I used white-flowering plants to bring light into this shady area, and also incorporated many scented and winter-flowering plants.
The ground layer is planted with shade tolerant perennials such as Brunnera macrophylla, Geranium macrorrhizum, Luzula sylvatica, Helleborus orientalis, Dryopteris felix-mas and Eurybia divaricata.
Below: Viburnum x bodnantense with evergreen Libertia formosa, and the seed heads of Eurybia divaricata. Photos from February 2024
Beech Gardens Lake
The shallow lake alongside Beech Gardens was planted with a margin of native wetland plants, including Yellow Flag Iris, Purple Loosetrife, Marsh Marigold, and Watercress. Blocks of Golden Reed, Phragmites australis 'Aurea' colour up brilliantly in the autumn
