Replace the woodchip and bark below your shrubs with a living layer of plants.
My last piece was about allowing grasslands – mainly lawns, to grow more naturally and to include flowers both for our enjoyment and for the benefit of those crucial insects, the pollinators. Here I will look in a bit more detail at the idea of the meadow as a garden and landscape element and how it can be combined with shrubs to create wonderfully diverse and ecologically intense ‘shrubland ‘gardens, replacing the ubiquitous woodchip and bark below your shrubs with a living layer of plants.
The ornamental meadow originally developed as a design concept, and has since gained huge popularity, in Europe and in North America. Its inspiration was the partly managed and partly natural grasslands of these regions – the prairie of North America, and the steppe of east Europe and central Asia as well as the traditionally managed hay meadows and grazing pasture of Europe. In fact the North American ‘prairie garden’ has a long history dating back many decades to the Landscape Architect Jens Jensen whose ‘prairie style’ of the early to mid twentieth century celebrated the space and native plants of the American Mid-West. Jensen worked with the architect Frank Lloyd Wright (whose Prairie Style architecture was one of the architectural landmarks of the twentieth century). So its history is long and renowned. Jensen’s prairie design included groups of trees and shrubs scattered in the flowered grassland. The prairie was also the inspiration for design with perennials by landscape architects Oehme and Van Sweden in recent years in North America. Prairie has a similar design meaning to Meadow in Europe and many of the forbs (broadleaved flowers), such as Echinacea, typical of these North American grasslands have also proven to be very successful in creating assemblages of late summer perennials in Europe.
Photo 1 Prairie planting on the New York High Line park, creating an impression of the natural grassland community that inspired it (Design: Piet Oudolf. Photo Fred Long).
In tropical, sub-tropical and even warm temperate regions Such as New Zealand there is a greater emphasis on tree and shrub based plant communities because these are the typical local vegetation or because they have the value of providing protection from the sun. Also, in these warmer climates the use of gardens is less seasonal and so there is a need for ornamental planting to provide colour and other interest throughout the year. The concentrated summer display season of temperate perennials combined with their long dormant period would leave large areas of the landscape looking rather neglected. However, a combination of shrubs with evergreen perennials such as Clivia, Hymenocallis, Strelitzia, Agapanthus and Anigozanthos, plus seasonal bulbs and emergents would provide an extended season of interest and consistent cover. The shrubs chosen for this important part need to be exceptionally strong on aesthetic interest with, I believe, at least two, preferably three points of major interest – flower, fruit, autumn colour, fragrance, ornamental bark, exceptional foliage interest, unusually elegant form etc. Examples include Cercis ‘Forest Pansy’, Hamamelis mollis, Hydrangea quercifolia, and perhaps Sophora ‘Dragon’s Gold’.
This is in fact the idea behind the traditional ‘mixed border’. It is a combination of shrubs with herbaceous perennials which became increasingly popular in the early twentieth century when gardeners began to include shrubs with herbaceous planting partly to help reduce the labour of maintenance and also to extent the period of interest. Many shrub species flower earlier than the main perennial season as well as, later in the year, adding autumn fruit and foliage colours to the late perennials flower.
Photos 2 and 3 This planting at Santa Barbara Botanic Gardens, California combines shrubs, trees and herbaceous all in a naturalistic way producing a ‘shrubland garden’ modelled on the chaparral communities typical of the region and featuring Californian plants such as Fremontodendron, Ceanothus, Clarkia and Penstemon.
‘Shrubland’ gardens would be very effective in areas currently devoted to shrubs with bark or woodchip mulch ground cover, or shrubs and trees in grass. In these kind of situations, there is a great opportunity to create small to medium scale naturalistic plantings that combine the best shrub and small tree species with grassland and herbaceous vegetation. In effect this would amount to adding shrubs to the popular meadow and prairie gardens and including herbaceous species that have a wider range of shade tolerance than the sun-demanding forbs of open prairie and meadow. There are, in fact, many good semi-shade tolerant grasses such as Deschampsia cespitosa and Anemanthele lessoniana and the sedges, especially Carex species such as C. dipsacea and C. dissita, are also excellent plants with which to create a meadow-like matrix in shadier conditions.
This kind of planting would add spatial and structural diversity to perennial planting, increasing the aesthetic value especially in the dormant season when shrubs offer branch form, bark and flower interest. The shrub component also gives a good wildlife habitat. Some examples of this kind of designed ‘shrubland’ exist, such at the Santa Barbara Botanic Gardens in California, modelled on local wild vegetation but enriched with a wider range of the most attractive species.
The potential of ‘shrubland’ gardens lies not only in regions characterized such natural vegetation, like Mediterranean climates and mountain areas, but also in forest regions where the ‘shrubland’ forms a seral stage of forest succession as a model for designed assemblages. These can be managed to stop further change to forest. The key to their success is to maintain the shrub canopy open enough to allow attractive herbaceous layers to thrive below. This will normally mean planting shrubs at distances from about two to five metres apart, though occasional tighter clusters are effective in creating structural diversity. The aim is to create a range of field layer conditions from moderately shady below the denser shrub species to fully open in the wider gaps as this will allow us to plant a wider diversity of herbaceous plants. ‘Shrublands’ with rich understorey really do suit the human scale of gardens in residential and parks and I find it surprising we still only think in terms of one type of plant in any garden area. Build up the layers to get more value from the space you have!
Nick has twenty years’ plus experience of landscape architecture professional practice in New Zealand and Britain. Before setting up his own practice he worked on significant landscape projects across the North of England as a Landscape Architect for Arnold Weddle, for Rotherham Metropolitan Council, and as Design Principal for ECUS, the Environmental Consultancy of the University of Sheffield. This work included a number of award winning landscapes of industry, new roads, campuses, urban regeneration and parks. Nick has worked for over 10 years in New Zealand, gaining broad experience of landscape design in the varied natural and cultural landscapes of the South Pacific.
In addition to professional practice, Nick has taught landscape architecture at universities in the UK (Sheffield and Gloucestershire), USA (Cal Poly) and New Zealand (Lincoln and UNITEC) and has a range of publications to his credit including the Planting Design Handbook (now in its revised second edition) and journal articles. He has recently completed a sabbatical period working and studying at the Department of Landscape, University of Sheffield, UK, with a focus on current thinking on ecological approaches to urban design and innovations in planting design for biodiversity, and working with international experts on urban ecology, green roofs and green walls.