Sustainable Landscaping at Piazza Nanni, Northbridge

Piazza Nanni is located on Fitzgerald Street at the western end of Aberdeen Street in Northbridge between St Brigids Church and the Farmer Freeway Tunnel western entrance/exit.

The Claise Brook Catchment Group has replanted the garden beds in Piazza Nanni with West Australian plants to create an easy to maintain, attractive landscape with low water and fertiliser requirements. Sponsorship was provided by the East Perth Redevelopment Authority (EPRA) who were responsible for the site at the time. The landscape plan was prepared with the assistance of the North Metro Catchment Group. Additional assistance was provided by the City of Perth.

Responsibility for maintenance of the landscape in Piazza Nanni has since been returned to the City of Perth.

Click here to download a report on the sustainable landscaping at Piazza Nanni.

Overview

Through the public landscaping in Northbridge, EPRA have sought to create a friendly intimate feeling with landscaped verges and plantings around street trees. However concerns have been raised about ongoing watering and maintenance requirements. Exotic plants are less suited to Perth soils and have higher watering and fertiliser requirements. Fertilisers can have off-site impacts on ground and surface water quality. The cumulative impact of landscaping with exotic plants across Perth is impacting negatively on the water quality of Perth’s waterways including the Swan River.

The landscape designed for Piazza Nanni in contrast uses West Australian plants which are suited to Perth’s sandy soils and climate, therefore requiring less input in the way of water and fertiliser. The plants used were carefully selected to provide a highly attractive landscape which will be easy to maintain. The landscaping will also be used to raise public awareness about landscaping with local plants and a sign will direct people to the catchment group’s website for further information.

Objectives

1.       Create a landscape using varieties of plants, local to the Swan Coastal Plain which are suitable for landscaping within an urban environment, providing a high level of aesthetics while requiring low input of water and fertiliser.

2.       Maintain landscape to achieve good plant health and appearance year-round.

3.       Raise awareness of the benefits of landscaping with local plants in the local and wider community, including among landscapers.

 Key elements of the landscape design

1.       Plant selection: Plants were chosen which would provide a variety of flower colour, foliage colour, size and form. In addition the size of plants was taken into consideration so that the mature size of the plants suit the location, and annual pruning is not required or minimised. The selection included mostly hardy plants which are very reliable. In addition two species of Banksia were included because of their distinctive appearance and iconic status as flora endemic to the region. All plants were selected from species that are indigenous to the Swan Coastal Plain.

2.       Safety: The landscape was designed to address safety and vandalism concerns expressed during community consultation. All plants have an open form and no dense thickets of shrubs will form which could provide shelter. Plants which are known to be a target for vandalism (primarily grass trees) were avoided. Edges of garden beds were clearly defined by planting with clumps of strap leafed plants (Dianella revoluta and Ficinea nodosa)

3.       Community and stakeholder involvement: Throughout the design and implementation the community and all stakeholders were involved through consultation culminating in a community planting day. This has resulted in a wide level of acceptance of the landscaping. St Brigid’s church community and the City of Perth grounds staff were seen as key stakeholders as they will be the principal users and have responsibility for maintenance respectively.

4.       Maintenance: The catchment group is committed to ongoing involvement, in partnership with the City of Perth, to ensure that the landscape reaches the objectives of being highly attractive, easy to maintain and raising community awareness of the benefits of landscaping with local plants.

 Landscape Design

Piazza Nanni is located on Fitzgerald St in Northbridge between St Brigid’s Church and the western entrance to the Northbridge tunnel. Just west of the Piazza, across a pedestrian/cycle bridge are the lakes of the Hamilton interchange, which are planted with tall eucalypt and other trees, (mainly Australian). The landscaping beside the Freeway west of the tunnel entrance is planted with West Australian trees and shrubs including many grass trees. Most of this landscaping is well below the level of Piazza Nanni, but is visible from the Piazza.

The landscape was designed to include a variety of flowering and non-flowering groundcovers, small plants, shrubs and trees to provide a variety of colour and form throughout the year. Colours in the Freeway landscaping such as the white bark of a eucalypt and grey foliage influenced the plant choices.

The Piazza contains 4 rectangular beds of varying sizes (from 3m X 4m to 7m X 5m). Each bed contains a tall Palm tree. While users of the church expressed a preference for replacing the palms with shade trees, this was beyond the scope of this project. The rectangular beds are at risk of being walked or driven over.

The Piazza also contains a long curving garden bed about 65m long and about 1.5m deep. There are a set of stairs overlooking the freeway at the western end of the long garden bed and a smaller bed 13m long between the steps and the pedestrian bridge to the Hamilton Lakes.

Design of rectangular beds

• Formal appearance of beds was maintained through plant choice and placement.
• All plants were small to medium in height to contrast with the palms.
• Corners anchored by group planting of either Ficinea nodosa or Dianella revoluta to define the edges and discourage trampling.
• Medium sized shrubs in groups of 3-5 in centre of beds.
• Smaller flowering plants along edges.
• Groundcovers to fill in gaps
• Larger rectangular bed included Banksia groundcover Banksia Blechnifolia.
• Bed 4 contains a rock with a plaque about the naming of the Piazza. So as not to detract from the rock, the centre of this bed was planted with a strong Grevillea groundcover Grevillea obtusifolia with the same corner and edge treatments mentioned above.

Design of long curving beds

• Small ghost gum Eucalyptus victrix were planted fairly evenly spaced along the garden bed with two in the bed to the left of the stairs and the remainder between the stairs and the road. These trees were chosen for their small size (to 5m) open form, and white bark.
• Dwarf Banksia menziesii (to 3m) were planted adjacent to some of the ghost gums, and away from reticulation to form a taller grouping.
• Groundcovers and prostrate shrubs were planted under and around the trees.
• In the open spaces between the taller trees, the medium sized shrubs were planted in groups of 3-5 plants with the taller plants to the back.
• Along the front small flowering plants (Patersonia occidentalis and Conostylis candicans) were planted in groups of 3-5 plants, with the Conostylis away from the reticulation.
• The ends of the long garden beds were anchored with clumps of strap leafed plants (Dianella revoluta at the western end) and Kangaroo paws (Anigozanthus species: of the Bush Gems range in Gold, Amber and Ruby). Clumps of 10-30 Kangaroo paws were planted either side of the steps and at the eastern end of the garden bed nearest to the street. Another small group was planted midway along the long garden bed. The flower spikes will reach 1.6m and the mass planting will be visible to passing traffic.
• Groundcovers were planted throughout to fill in gaps. Kennedia prostrata prefer shade so were only planted in the long garden beds which will be shaded when the trees grow up.
• Several groundcover banksias Banksia blechnifolia were planted through the long garden beds.

All garden beds were mulched with Pine bark mulch from Soils Aint Soils which is coarse and airy.

Plant List