Retired territory public servant and landscape designer Chris Slotemaker de Bruine first proposed a flower festival for Canberra in 1986 as part of plans for Australia's Bicentenary celebrations two years later.

He worked on the annual festival until 1990, in partnership with horticulturist Peter Sutton and the City Parks Administration.

In a letter to Chief Minister Andrew Barr this month, Mr Slotemaker de Bruine said many people believed the festival's original purpose was at risk of being overshadowed by commercial elements.

The event cost ACT taxpayers $5 million last year, bringing reported economic benefits of $47 million to Canberra.

As the government considers options after the end of its exclusive tenure at Commonwealth Park from next year, Mr Slotemaker de Bruine said splitting the event across sites around central Canberra would drive up costs and reduce attendance due to poor public access and car parking.

The government's five-year contract with the National Capital Authority ends after this year's festival and Mr Barr has flagged using different areas including the West Basin lake front between the city and the museum, Glebe Park and other city sites.

The NCA wants to reduce disruption at Commonwealth Park for about eight months each year. Mr Slotemaker de Bruine first considered alternative locations for the event in a 1989 report to government.

"Any festival has commercial possibilities, however, it appears essential that the balance between financial aspects and the main attraction should be weighted to that main event," he wrote.

"In the case of Floriade that balance is currently heavily directed towards the commercial side."

Mr Slotemaker de Bruine proposed the mature arboretum opposite Government House and associated space along Yarramundi Reach as an effective single-site location for the festival but called for an expert study bringing together horticulturists, engineers, designers, logistics experts, financial advisers and marketing agents.

The government has ruled out the National Arboretum - a site which Mr Slotemaker de Bruine says is not suitable for spring flower growth. The expert group could survey all possible sites, with new infrastructure for a single venue taking as long as two years to develop.

"Floriade has huge international possibilities, however, creativity is required to harness such potential," he wrote.

Mr Barr said the government had considered various options around the city in the past for Floriade.

"There are a number of considerations that determine the location for a unique event such as Floriade," Mr Barr said in a statement.

"Our discussions with the National Capital Authority have been very positive to this point, and our view is that the event will always have a place at Commonwealth Park beyond 2015.

"However, this is an opportunity to grow Floriade by activating new areas around the central business district. Expanding into Civic, Glebe Park for example, is an affordable option, as many of the infrastructure needs such as parking, toilet facilities and electricity are already available."

Paid parking in the parliamentary triangle has left the government with a large parking bill at Commonwealth Park. The Regatta Point spaces were expected to cost $185,000 this year, up from a $57,000 parking bill last year.

In 2014, the National Capital Authority received $107,000 last year for Floriade-related "cost recovery".

On Tuesday, Mr Barr said further announcements about the future location would be forthcoming.