Introduction
For Ian and Helen Lawrence their fences falling down in 2001 provided an opportunity to rethink the design of their resource intensive cottage garden. As fourth generation Australians they asked themselves what should an Australian urban garden look like?
The Lawrences believe a garden should have a range of aesthetic, recreational, environmental and contemplative properties. They removed thirsty lawns and exotic plants and replaced them with a palette of native plants, such as Westringia, Correa, Grevillea, Callistemon, Acacia and Indigofera. Using water wisely and protecting the environment forms the cornerstone of their garden philosophy.
By using tanks, swales and pervious surfaces so water is retained on site they have minimised the high rate of stormwater run-off which adversely impacts water quality and ecology of local creeks and wetlands.
Water harvesting
The major focus in their garden has been on harvesting water for use in the garden. Staggeringly they have reduced their potable water use by 90%, a figure that could be achieved in many existing Canberra gardens and new developments! Half of the water used for garden irrigation comes from tank water, 40% from mains water and 10% from grey water.
Rainwater tanks
Water is collected in three rainwater tanks (2 x 500 Litre and 1 x 4500 Litre), via swales and the owners have made extensive use of pervious materials which allow water to percolate into the ground.
Grey water system
A grey water system filters and stores laundry water and is used for garden irrigation. Using recycled 150 Litre food grade containers, water enters the first tank through a simple home-made gauze filter. This removes lint and other solids. The water then passes through a sand filter which removes fine particles. Water is then stored in the first tank for 12 to 24 hours. This water is then pumped through a sand filter to a second 150 Litre tank. From there it is pumped through an in-line filter to the garden drip irrigation system. On average, their two person household generates around 2000 Litres of grey water per month from their laundry.
The Lawrences use non-phosphorous, low salt laundry detergent to protect their plants and soils. Many native plants such as Grevillea can die from phosphorous applications. Sodium from salts can also adversely affect plant metabolic processes and reduce the drainage capacity of the soil. Applications of gypsum can help recover the composition of the soil.
>> Grey Water System - Ian Lawrence: as web page
Garden pond
The piece de resistance of the garden is a large pond. This 16m2 water feature is sited on the lowest point of the block and is visible from the living areas of the house. Water is directed to the pond from swales (drainage lines) lined with geotextile fabric.
The pond has reduced stormwater leaving the block by around 90% for storm events, helping to protect downstream waterways from scouring and nutrient overloads. Water overflows via a spillway which is attached to the stormwater drain, preventing flooding into their downhill neighbour’s garden. During Summer the pond is topped up with water collected in the rainwater tanks.
The pond is lined with a pond liner and has a maximum depth of 300 mm to ensure the safety of visiting children. As an added precaution a pool lock has been added to the side gate.
The pond is maintained by netting any algal build up which would adversely affect water quality and annual cutting and removal of excess wetland plants. |
|
Native wetland plants including Marsilea (Nardoo) and the locally occurring Myriophyllum create strong textural interest on the pond's surface. Photo Edwina Richardson. |
As well as acting as a detention basin, the pond has been planted with a variety of native wetland plants. Rushes like Eleocharis, Juncus and Schoenoplectus form strong vertical accents in the pond. Marsilea, Nardoo (an aboriginal bush food) and Myriophyllum, Water Milfoil, form a tapestry of foliage on the water’s surface. As well as being attractive, these plants provide habitat for pond dwellers and release oxygen into the water. Wetland plants can also perform a role in trapping nutrients entering a pond.
This suburban wetland attracts a variety of wildlife that is of great interest to Helen Lawrence who trained in microbiology. Dragon Flies and Damsel Flies regularly visit the pond, whilst three different frog species have found their way into this wet zone of the garden.
Birds
A range of flowering plants in the garden attract many of the larger birds commonly found in Canberra gardens, such as Crimson Rosellas, Currawongs, Magpies, whilst a number of smaller birds such as Silver Eyes, Wrens and Thornbills also visit the garden. The birds frequently bathe in the pond providing a delightful spectacle for the Lawrences and their visitors.
A mix of hardy native groundcovers such as prostrate Grevillea, Convolvulus mauriticanus, Brachyscome multifida and Myoporum parvifolium replace the resource intensive lawn. This plant material is green throughout the year providing seasonal interest and allows views from living room windows to the pond. Photo Edwina Richardson. |
|
Garden visits
The Lawrences have generously opened their garden within the Australian Open Garden Scheme in 2004 and 2005, as well as welcomed Landscape Architecture students from University of Canberra and included it in tours of Sustainable Gardens held over 2005/2006. Their garden will be included in a tour of sustainable Canberra gardens, organised by Edwina Richardson for the Australian Open Garden scheme in April 2008.
|
A sense of place
As well as incorporating native plant material into the garden Helen and Ian acknowledge the local vegetation types such as Eucalyptus woodland. In their front garden they have retained large local species of Eucalyptus and begun planting an appropriate understorey using native grasses and shrubs.
This garden is an excellent example of how Canberra gardeners can improve their water use.
For more information:
Ian Lawrence’s notes from sustainable Canberra garden seminars
For more information on the Lawrences' water harvesting methods
|
