Life

Site planting

Provided by Simon Bell: Senior research fellow: OPENspace Research Centre

 

What, Why, When, How, Extras 

 

What is it?

Figure 1

Fig 1. Street trees enhance the city street and provide shade in summer. 

Site planting is the use of plants of various types on a site to perform a range of functions. These functions are not merely ornamental, although this is an important aspect. Plants may stabilise slopes, intercept water flows, filter pollution (water and air borne), provide shade to site users in hot conditions or shelter in windy conditions. They may provide a surface for different uses, reduce glare and heat reflection, reduce building energy demands and mitigate sound and visual pollution. In addition they may form part of a wider green infrastructure in an urban area and help local wildlife by providing a range of habitats.

 

Why use it?

The use of plants, given the range of potential benefits described above, should be a major consideration in any development but should not be considered an 'afterthought' or a merely decorative element to be added once the built structures are designed or constructed. You should always ask yourself whether a solution involving plants can be used instead of hard or engineered solutions. Thus the use of plants should be considered an integral part of the development and appropriate specialist skills of a landscape architect should always be sought – the landscape architect is as important a member of the team as a structural engineer.

 

When to use it?

Except in the smallest spaces around buildings in a very difficult environment, there are always going to be possibilities to integrate site planting into a design and to improve the architectural aspects. Planting can provide an important setting for a building or be used to provide a range of benefits as described above both for the building and the users, which may be cheaper and more attractive than by using constructed solutions.

 There are many different types of plants which fulfil different requirements: height variations (trees, shrubs, ground covers), seasonal benefits (evergreen, deciduous), aesthetic values (form, textures, colours, scents). However, some plants can also cause problems such as damage to foundations or perceived loitering places for criminals, so that expert guidance is always needed.

How to use it?

Key points:

  • Consider how trees can be used for helping to compose the setting of the building, for providing shade and shelter and for intercepting pollution. The key aspect is the eventual mature height, the suitability for the conditions, the tree form and its effectiveness at capturing particulate pollution. (see figure 2.)
  • Consider how lower level plants (at around eye level or slightly taller) such as shrubs can enclose space, screen areas from views, provide shelter and look attractive at all seasons without providing loitering places or causing an accumulation of rubbish. (see figure 3.) 
  • Consider how ground covers such as grasses, low shrubs or herbaceous plants can be used to stabilise slopes, to provide surfaces for different uses, to keep storm water infiltration functioning into the soil and for sustainable urban drainage. (see figure 4.)
  • Consider the use of climbers on blank walls of buildings.
  • Consider how to link site planting with vegetation outside the site, so integrating it into the urban green infrastructure and to improve its value functionally, socially and ecologically.
  • Ensure that long term maintenance and management of the vegetation is built into planning for the after care of the building.
  • Remember that plants start small and grow bigger, so that the completed project construction is only the start of the development of the landscape.

 

Figure 2

Fig 2.

Figure 3

Fig 3.

Figure 4

Fig 4.

 

Design procedure:

  • Step 1: Build on from the design procedure discussed in the strategy on landscape design – urban by considering all the roles plants could play in the development instead of built structures or hard surfaces. 
  • Step 2: Plants need growing conditions of suitable rooting medium (soil or soil substitute), water (not too little and not too much), light (some are shade tolerant, others need full sunlight) and nutrients, so check what the environmental conditions of the site are or will be after construction. Protect any plants t be retained on the site during construction so that roots are not disturbed.
  •  Step 3: Select the appropriate plants according to the overall site design, by type (trees, tall shrubs, low shrubs, hedges, ground covers, grass, aquatic etc), by species/variety (suitable for the environmental conditions and for the function). 
  • Step 4: Prepare a site plan showing which plants should be planted where and prepare any special details such as tree pits with special drainage and watering facilities or the areas where soil will be built up behind retaining structures or any water features which require linings etc.
  • Step 5: Prepare a specification for the types of plants and the way they will be delivered from the nursery and planted together with their immediate aftercare. This is a very specialised aspect, which needs professional guidance.
  • Step 6: Ensure that a plan for maintenance and management of the plants is properly prepared for the short and long term, with allowances for replacement of failures in the year after planting. 

 

Related strategies

Site planning

Landscape design: urban

Landscape design: rural

Rainwater catchment

Water conservation

 

Take this further

  • Austin, R.L., 2002, Elements of planting design, John Wiley, New York.
  • Bradshaw, A., B. Hunt & T. Walmsley, 1995, Trees in the urban landscape, Sponpress, London.
  • Clouston, B. (Ed.), 1990, Landscape design with plants, Butterworth-Heinemann, Oxford.
  • Hitchmough, J. & Fieldhouse, K. (Ed.), 2004, Plant user handbook, Blackwell, Oxford.

Case studies