Up he comes from the underground into the soulless square, takes out his trowel and digs and gouges between the cracks of the paving stones and plants the shoots - a line of green in the grey of the granite.
Potsdamer Platz today is a long way from what it once was - the pulsating heart of Weimar Berlin, the city's hub of charm and cafe society.
It was where the tram routes met, where the literati met and, no doubt, the not-so-literati. It was the place of chatter and deals and morning-after-the-night-before coffee.
Today, it is, I think, a pretty soulless place.
It was devastated in the war and left desolate after it - split down the middle by the Berlin Wall. On the wasteland freed for development by the Wall's demolition has arisen the cold glass of the Sony Centre, with its windy canyons of offices.
A new sort of desolation, you might think. Until that is, Petrus arrives with his gardening tools.
Petrus Akkordeon, you see, is a guerrilla gardener. He told me he does it to make people happier.
"Everything is grey," he says. "No flowers. No trees. And if you plant one flower, the whole place changes."
"For several seconds, it's a nice place. People see these flowers and feel better for a moment. There's a man planting on Potsdamer Platz, he must be crazy," he says, describing himself, of course.
Fascinating post about people marching to a different drum in Berlin:
Wikipedia on Guerilla Gardening --> http://en.wikipedia.org/wiki/Guerrilla_gardening
Seed bombing --> http://en.wikipedia.org/wiki/Seed_bombing
By coincidence, Charles Hugh Smith's post today is on gardening as an antidote to derealization: I Dig Dirt.
And I myself am about to prepare a stir fry with my garden-grown collard greens for dinner. Bon appetit!