Once the space has been organised (see earlier posts in this series), more thought can be devoted to the details of the garden design. In truth, detailing should be at the back of the designer's mind from the very beginning, because it is through the details and materials that the mood and style of the garden can be conveyed, every bit as much as through the spatial arrangement.
Materials have to be suited to the garden as well as to the regional, vernacular styles of building and garden making. It is for this reason that I feel strongly about the use of plastics, glass and stainless steel in modern designs - they are available everywhere, have an immutable appearance and do not reflect any traditions of building for most of the gardens they are used in. For show gardens, where there is no context within which the garden exists, they offer unparalleled opportunity to experiment with shapes and structures, and in a setting of modern architecture they are clearly appropriate.
Gentler surfaces, such as that offered by Cor-ten steel, are a halfway house between the modern and traditional - the modern material picks up the colours of earth and brick, and is a subtly changing presence as it weathers.
The best materials to use in most gardens will be those which have a counterpart in the local architecture or which are long-established as the most suited for their particular purpose. In an exterior context we are talking about stone (limestone, flint, sandstone), brick, iron, timber, gravel and tile.
Relating the materials to the climate and building tradition of the area brings a groundedness to the design - it will sit happily with the house it belongs to, and will be a far less jarring imposition in the landscape than if the materials are alien. Obviously a city courtyard, in which the relationship of the local architecture to traditional forms and the landscape has already been stretched to breaking point offers greater scope for the use of more modern materials, but my feeling is that there are plenty of ways of generating a modern look in gardens anywhere with traditional materials if they are handled sensitively.
Think about alignment, spacing, flush finishes, juxtapositions of the unexpected, combinations of materials exploited for their differing structural qualities, and there is plenty of scope for creating something unusual yet true to the vernacular traditions of a site. Ironwork set in Bredon gravel, timber of differing widths and spacings to clad fences or shelters, unplaned timber contrasted with highly finished render or tiling, decking planks interspersed with channels of gravel or grass - all these could (and do) enliven contemporary exterior design, and are examples of the ongoing dialogue that a garden has with the surrounding landscape and with the people who create it.