She told the recent Landscape Institute Awards that landscape architects have to "seize the opportunity" and "step up to the plate to promote with confidence the art and science of landscape architecture".
The keynote speaker said: "Help us promote and show the importance of landscape in everyone's lives. You have many brilliant landscapes but you need more - politicians have said it's over to people to take on what used to be done for them by others.
"But without your help that vision will be without meaning and effect. People are not ready for it yet. You need to demonstrate leadership and passion to create a better and kinder world."
Warhurst said she is in "awe" of landscape architects for weaving together skills to meet "game-changing agendas" of climate change, sustainable engineering, expanded woodland cover, recreation and sustainable transport links.
But Landscape Institute president Sue Illman contrasted this need with a grim reality: "It's been a year of massive cutbacks. However, we've made progress on recent guidance for green infrastructure and plants and made a big impact on Open House London."
The Olympic Park won the President's Award at the ceremony, while the Olympic Delivery Authority won the Landscape Institute Peter Youngman Award for extraordinary achievement.
The authority's chief Phil Askew said: "Landscape architecture and architecture have shaped the process. The project has set new standards for design and it demonstrates the importance of green infrastructure."