Organisers of the Taunton Flower Show are looking for a new home after being told the council wants to charge a "five-figure sum" for using its venue.
The event has been held in Vivary Park for the past 166 years and up to now the council has not made a charge.
"We've come to this point with a very heavy heart but the decision made itself," a show spokesman said.
Taunton Deane Borough Council said it needed to help pay for the "wear and tear" the event caused.
A council spokesman added the money would also make a contribution for the loss of public access to the park during and around the time of the show.
Adrian Prior-Sankey, from the show, said it fully understood the council's position.
"They've got something approaching a £700,000 gap in their finances - there's really no animosity - it's a very hard-nosed business decision we need to come to."
Mr Prior-Sankey said the charity had previously asked the council to come into partnership with it - and that the show would be prepared to share any "bounty" on a good year in return for it not being charged on the years it made a loss.
Taunton Deane Borough Council said the charge was a planned cost increase "which had been brought to the show organisers attention in January".
It added "up to this point the use of the park for the flower show had been free".