The garden at the London Wetland Centre in Barnes will replace a sustainable show garden created by Cleve West a decade ago. Visitors will be able to walk through the new garden, unlike West's, which was primarily for viewing.
Dunnett, a reader in urban horticulture at the University of Sheffield, is leading the design but will work with the Landscape Agency's landscape director Matthew Wilson on technical aspects.
The Wildfowl and Wetlands Trust (WWT), which runs the Barnes site, contacted Dunnett after he exhibited a sustainable show garden at the RHS Chelsea Flower Show last year.
"It is not a carbon copy of the Chelsea garden, but we did want to show the garden can achieve environmental benefits as well as looking great," explained Dunnett.
West's garden was one of three sustainable gardens at the site, of which two will remain. "The existing gardens were almost installations, so it was difficult for people to imagine them as a garden they could create at home," said Dunnett.
WWT centre developments manager Simon Rose added: "We didn't want the new design to look at all like the old garden."
The 400sq m garden is being funded by a £50,000 grant from the Royal Bank of Canada, which must include the professional fees as well as interpretation.
To meet the tight budget, Dunnett and Wilson will source reclaimed materials and planting will be assisted by students.
Wilson, whose TV show The Landscape Man launched last night (22 April), told HW that his role was "really to support Nigel Dunnett" with the construction detailing and plan drawing.
He added: "Because I live on the doorstep, I will be keeping an eye on it." Work is expected to be completed in July, with an official launch by Alan Titchmarsh in September.