For a single day, I traveled around Berlin on bus, tram, underground, train and of course good old shank's pony to see what it offers for anyone looking to lead a sustainable, environmentally positive existence or simply to engage with nature. What better place to start first thing, than with the scent of freshly baked goods …

08:30
To step behind the counter of Weichardt Brot in Berlin's western district of Wilmersdorf is to enter a Tardis-like hive of activity in which men and women dressed in white mill, knead, roll, twist, cut, baste and bake at a speed that defies the eye.

Devoted to supplying the city with a crust made from ingredients grown in keeping with strict ecological guidelines, it was one of several organic bakeries taking part in a week of activities to show Berliners what goes into the bread that forms such a fundamental part of their daily diet.

I got there ahead of the crowd assembling outside for a tour of the bake house. "People are really interested," Yvonne Neumann, who runs Weichardt, told me. Her parents came to West Berlin forty years ago, and became the pioneers of organic bread in the divided city.

"It wasn't easy," she said, describing how her mother would sell what her father baked outside kindergartens. "And because of the [Berlin] Wall, they had to get special permission to have the grain brought in."

They were driven by a "conviction" that has not only endured in their own growing enterprise, but which has also taken root in city's collective mindset. Organic is not the anomaly it once was. The queue at the door was evidence of that.

11:30
From the bakery, I headed way out east to what used to be a sprawling area of industry, which has now been reclaimed by nature, and in 2003 was turned into the 100-hectare Herzberge public park and environmental education center. As I got off the tram among lilac trees and lush fields of green, I felt like I was miles away from the city in which I technically still stood.

Birgit Wackwitz teaches children from all over Berlin about the natural world around them - she took me around the park. I'd been going to join a group of kids lined up to learn about the incredible features of the humble dandelion, but they had canceled last minute.

So, it was just the two of us - plus a flock of Pomeranian coarse-wool sheep, birds, trees, flowers, insects and hundreds of sand lizards. That was kind of exciting.

I asked about the chances of a reptile crossing my path. "I've never seen one," she said. "But then again, I don't tend to sit down for very long."

When we did pause for a moment, it was so she could show me the hidden secrets of the dandelion - this to the lyrical tune of a male nightingale marking his territory. And as we listened, Birgit Wackwitz suddenly jerked and reached for her back, up which one of the elusive lizards had decided to crawl. Nature, beautiful nature.

13:30
All that fresh air made me hungry (is that a myth?), so I headed back west, to Schöneberg to find some lunch. Find is the operative word here, because in order to get some food, I first had to locate a fridge. It took me a while, but I eventually sniffed it out in the car park of a Baptist church. Obviously.

It's one of a few across the city in which food rescuers can put what they save for others to come and take. I took a good long look at it before reaching for the door handle. Drum roll … Or maybe it was just the rumble of my tummy … Full-on Mother Hubbard moment. It was, to my extreme disappointment, empty. Not so much as a crumb inside.

Just as I was about to leave, a food rescuer turned up. Like me, he wanted to see what was in it. But unlike me, he was happy to its shelves were bare, because that, he said, means people are on board with the waste reduction movement. Can't argue with that.

15:30
Next stop: Trial and Error in Neukölln. Active in urban gardening, upcycling and solidarity economies, their weekly calendar is replete with opportunities to engage with a more sustainable lifestyle. I was there for the swap meet, which opens twice a week and invites "customers" to bring and take what they want. Or just one of the above. No rules, really.

"We have people who donate three bags and others who turn up with two rucksacks to fill," group member Jenny Weber told me, adding that they've often discussed the ethics of that. "What if they then go and sell it at the flea market?" she pointed out. "But we decided it doesn't matter, because we live in abundance, and everything is always in flux."

With that in mind, I hung up a couple of shirts I'd taken with me, and picked out one for a friend. Then I was on my way. As a parting gift, they gave me a basket of strawberries - one of dozens that had been rescued and given to them that morning. On the my next train, a homeless man asked for food donations. I gave them to him.

17:30
Last stop was way out west, in the ancient district - formerly a city in its own right - of Spandau. Besides having its own citadel, which dates back to the 1500s, it is also home to not one, but two repair cafés. The name is true to what happens inside. There's coffee, soft drinks and cake. And there are repairs.

When I got to one of them, much of the huge table had been given over to a half-gutted flat-screen TV, but men - and yes, the experts were all men - were also dissecting headphones, a vacuum cleaner and a video camera.

"The main idea," Norbert Überfeld, who organizes the events, told me, "is to take a stand against our throwaway society."

A stand in which some 20 people participate each time the café opens its doors - with a hit rate, Überfeld told me, of around 60 percent. They're also now calculating how much CO2 the team of volunteers has managed to save over the past four years by fixing rather than replacing. I'm watching that space.

19:30
On my way back to the bus stop that would take me to the underground that would take me to the train that would take me to another train home, I passed an old phone box repurposed as a mini-library, the likes of which have also taken root on Berlin's eco-map. A map on which the green areas come in all shades and depths, and which are quietly spreading.