Twin skyscrapers awash with greenery are set to loom over Melbourne's Carlton Gardens, after the $250 million project passed a major planning hurdle.

City of Melbourne officers say they will not object to a 64-level development at the site of the Telstra Exchange at 288-326 Exhibition Street.

Artist's impression of twin skyscrapers proposed for the Telstra Exchange site on Exhibition Street. Credit:Fender Katsalidis and Cox Architecture

But they issued an unusual warning.

The council's green infrastructure experts said plants installed high up in the towers may struggle to survive the city's hot summer winds.