Planting six trees in Blackpool town centre and building an underground system to keep them alive has cost £174,000, the council has revealed.
Conservative Councillor Gerard Walsh, who put in a Freedom of Information (FOI) request to find out the figure, questioned if it was "value for money".
Blackpool Council said it had spent a government grant and the resort "deserved a wonderful street scene".
The latest bill comes three years after the council spent £100,000 on 10 trees.
The response to the FOI request said it cost £4,400 to plant the six trees in Edward Street with the rest of the money used to create a system underground to ensure they survive.
The money has come from the £7m government-funded quality corridors project to upgrade town centre streets.
Mr Walsh asked a meeting of the full council: "With the cost of living crisis, I ask is that value for money for the Labour group?"
Labour leader of Blackpool Council, Councillor Lynn Williams, defended the spending.
She said it came from government grants, which would go to other towns if Blackpool did not apply for them.
Ms Williams said: "Are you saying you don't want us to apply to your government for that money for these schemes?"
"I think Blackpool deserves the best technology to ensure we have a wonderful street scene," she added.
The FOI response said traditional methods of digging out a pit and filling it with soil have "almost always resulted in failures of the trees".
"A tree really requires a full grass verge with deep top soil to give space and medium for roots to grow and for them to find moisture in dry conditions to allow the tree to survive," it added.
"This is particularly true in the windy conditions that Blackpool generally experiences."
Robert Gomm, co-owner of the Upside Down Coffee Shop on Edward Street, said: "In the long-term as the trees develop, they will add to the aesthetic of the street.
"I'm delighted to see more greenery."
The 10 trees planted on Cookson Street are all thriving three years after being planted, the Local Democracy Reporting Service said.