Scottish turf specialist Stewartsturf was commissioned to grow turf to allow the new Scottish Water buildings to blend in with the surrounding Pentland Hills.
Duncan Forbes of Stewartsturf said: "This project came on the back of the work we did for the Scottish Parliament, where we grew a wild flower mix to mimic the conditions of the grass and flowers on nearby Arthur's Seat."
In conjunction with architects BDP, the firm devised a seed mix including wavy hair grass Deschampsia flexuosa, meadow buttercup Ranunculus acris and common sorrel Rumex acetosa.
BDP landscape architect Kath MacTaggart said: "This took about 18 months altogether, from ordering to getting it to come on to the roof. (The process) takes a lot longer, but it's worth it.
"It's important in terms of local biodiversity, so we tried to develop this mix based on what was growing on the Pentland Hills - it preserves the character of the area."
Forbes explained: "A special seed mix that includes many of the species that grow naturally in the Pentland Hills was developed and sown over a year ago.
"It included several tap-rooted species that have never been grown in turf, so we had to develop new ways of growing and harvesting the turf in order to retain as much of the root systems as possible."
Work began on laying turf on the 7,000sq m roof last month and it has been transformed into a meadow. "The turf established itself very quickly and has grown away rapidly, so we are delighted with the results so far," said Forbes.
Stewartsturf is now in talks with a Scottish seed producer. "We aim to produce a fully locally-produced seed for the Scottish market," added Forbes.