Drought Tolerant Couch Grass Trials at Parliament House
In 2008, as part of a review into landscape sustainability, Landscape Services conducted a trial of drought-tolerant couch grass in selected areas around Parliament drive. Four different couches were assessed for ease of establishment, water usage, fertilizer requirements, wear tolerance and general appearance right throughout Canberra’s seasons.
Following the trial, two suitable couch grass species were selected and are now used to replace some 20% of turfed areas around Parliament House. The new grass, which requires 50% less water than the original grass, can be observed in the locations shown below.
At this stage, no further changes to the grass design are planned for in other areas of Parliament House. We will continue to monitor the water used for lawn irrigation and consider future additional measures for reducing potable water in the landscape.
The four different varieties of couch trialled were: Conquest, Grand Prix, Santa Ana and Legend. All varieties were installed in early January 2008 using turf roles.
After three years of observing the couch grass trials, Landscape Services determined what it considered to be the two most suitable couch grass varieties for the Parliament House site. These were Grand Prix Couch and Conquest Couch.
Grand Prix was chosen for areas inside Parliament Drive and for the sports field. It possesses a fine texture and good colour during Canberra’s warmer months. It also performs well when used in a sports turf situation.
Conquest has been used in areas outside of Parliament Drive. It has a slightly coarser leaf texture than Grand Prix and is well suited to its location surrounded by native peripheral gardens.
Both of these couch varieties go into dormancy during winter in Canberra. This affects the colour of the turf, turning it a pale yellow colour. For aesthetic purposes, over-sowing some of these couch areas with transitional rye grass is performed to provide additional greening during winter. The rye grass is sown into the couch in autumn and is transitioned out in spring using selective herbicide. The rye needs to be removed every season as it will out-compete the couch grass. Areas of couch that are not over sown include the viewing strips, Ministerial entrance, front lawns and Parliament Drive. These couch areas also require the use of selective herbicide in winter to keep them clean from grass and broadleaf weeds that invade because the sward is thinner at this time.