Planting in a streetscape environment is usually more complex than a parkland environment. The streetscape needs to serve the movement needs of vehicles, cyclists and pedestrians, allow access to adjacent properties, and carry overhead and underground services. The road verge is where weekly rubbish removal takes place. It often includes signage, telephone poles, as well as trees.
Streetscapes are generally highly disturbed landscapes that can be hostile to plant growth and performance. Adverse factors include soils with altered chemical and physical properties, particularly compaction and permeability; small soil volumes for planting; low maintenance and resource inputs; the need to manage traffic to conduct maintenance; and constraints from the placement of services or adjoining infrastructure.
Failure to recognise the tough realities of the streetscape can result in dead, poorly performing or unattractive plantings that create a negative perception of urban vegetation, increase maintenance inputs, including replacement, and create poor quality, unsustainable urban landscapes.
To maximise the chances of successfully making an attractive, biodiverse streetscape planting, it is important to:
- Analyse the site.
- Prepare the site for planting.
- Select plants using clear criteria and design.
- Develop a maintenance plan.
- Consider using additional habitat elements.
1. Analyse the site
The best approach to establishing a biodiverse streetscape will be influenced by surrounding infrastructure, aspect, shade, soils, existing vegetation and the need for irrigation. Analysis should focus on determining what can be realistically changed to increase the success of the planting, and on ensuring that the selection of plants can tolerate the site's environmental, physical and maintenance constraints.
Site conditions are especially important to understand in areas that can’t be significantly improved, such as beneath tree canopies (for example, where tree roots may get damaged by excavation) or where adjacent patches can’t be treated (for example, turf that is likely to invade). In some cases, retrofitting a streetscape site for biodiversity planting may be impractical, for instance due to contamination or high weed loads in the existing soil and the high cost of excavation and disposal.