Professor Ken Taylor, a former city planner in Manchester, came to Canberra in the 70s to work on one of the rare planned capitals in the world. Back then it was famous for its lush design, its hills and valleys, and planning experts travelled from all over to see how it had been done.

"I doubt they'd visit now," Professor Taylor said.

The problem, he claims, is that when the territory gained its own government in 1988, it also lost a dedicated authority to manage the vision of the city.

"Landscape was the bones on which [it] was built, it was the defining feature," Professor Taylor said.

"All the visionaries of Canberra [including] Burley Griffin and Charles Weston, had that thread running through their plans.

"Where is that vision now? You walk around Belconnen and the buildings are hard up against the pavement, there's no room for planting.

"This is not Canberra."

His views are echoed by former Canberra planners Tony Powell and Professor Patrick Troy, who claim planning approaches under a local government have been at best confused and at worst "destructive", putting profit before good planning principles.

But director-general of the Environment, Planning and Sustainable Development directorate Ben Ponton says he has a vision.

Since taking up the job as the city's head planner last year, he has launched an extensive "democratic" consultation process and installed a new team of expert architects and planners to advise major projects in the city.

It's part of what he describes as a shake-up in Canberra's planning, which he concedes has not always been done as well as it could have been.

"Canberra is growing, and we have to make sure we cater for that growth sustainably," Mr Ponton said.

"But we don't have to lose its garden city character, we just have to go about density in a clever way...building with the landscape and keeping the things Canberrans value.

"Everyone has a view on planning and people know their local areas well...I'm not afraid of having that conversation."

The ACT government's current planning strategy, which is up for renewal, does make mention of the city's landscape under its objectives but Professor Taylor said most of the "action" had been on increasing density, particularly in the inner north, often at the expense of open spaces such as courtyards and community gardens.

"I'm not against density in principle...but in all the great cities of the world, people don't remember the buildings, they remember the spaces," he said.

"That's where it is."

Mr Ponton said increasing density along planned light rail transport corridors was part of the city's plan, but that approach varied between areas.

The debate comes as the National Capital Authority, which manages Commonwealth land in the territory, continues to float its proposal to impose "one-dwelling rules" in parts of Forrest and Deakin in order to preserve the area's 'garden city' character.

Set to review the ACT's own Territory Plan, Mr Ponton said planning laws did not have to be so rigid.

He insists the city has a "strong planning authority" in the ACT government and new projects are putting design first. Tasked with developing the city's climate change strategy, he said he was also looking closely at its canopy.

"But Canberra will not stay the same...the original Griffin plan only covered central Canberra and even then it imagined a more compact city with medium density and transport," Mr Ponton said.

"[Planners] then moved away from that to a more sprawling model. Now in contemporary planning we've sort of come back to Griffin."

Professor Taylor, Mr Powell and Professor Troy will speak at a seminar organised by former Labor chief minister Jon Stanhope on Thursday.

The same night, a series of talks will kick off as part of the ACT government's planning strategy renewal.