Costa made a no-dig garden at the Sustainable Living Expo held a couple of weeks back and it was an energetic performance taking over an hour to complete. That might seem like a long time when you consider that everything needed to put the garden together was prepared in advance and on-hand. But with Costa on stage we certainly got more than just a simple demonstration in practical horticulture, regardless of how effective it was; we also got a beginner's course in sustainable gardening and tips on managing biodiversity in the backyard.

The biosphere is singular, he began. If the person living on the hill (pointing north-westward in the heat of mid-morning) sprays their garden with pesticide (squirting the assembled onlookers with water from a plastic bottle labelled with a skull-and-bones) it will filter down to the creek (which flows west-to-east through the municipal park where the expo took place) and affect the organisms living in it. Everything we do in our garden is public. There is a disjoint between notions of private property and the way the biosphere operates, he told us as we listened to his vigorous talk on things some had come to the expo specifically to listen to.

In fact, the talk took up most of the allotted time. A minder circled around the outskirts of the gathered crowd occasionally shouting out the number of minutes remaining before time would be up. His name is Nick and he's from the UK. He told me after the crowd had dispersed that working with Costa was stimulating but I got the impression that it was also quite challenging.

At large, Costa began to assemble the no-dig garden, starting with slabs of hay taken from one of three bales positioned at the back of the open auditorium near the loudspeakers. On top of the base layer he added soil from a nearby trailer, fertiliser in the form of rock, and more layers of hay until the mound stood about 30cm high. At this point he threw himself on top of the mound while telling us how much he loved no-dig gardens. Later he added a range of plants from a number of black, plastic containers.

Costa didn't forget the small people, either, and invited them to help him assemble the no-dig garden by assigning simple tasks to two boys who had been infected by his dynamic delivery. They ran about fetching and throwing, caught up in the spirit of fun that overtook the whole crowd. The sun beat down but nobody minded or took a break to visit one of the drinks stands located nearby. There was too much to see right in front of them.

With the performance ended, Costa began to hand out seedlings to a number of children who had hung around waiting for a chance to secure an autograph or just to say 'hi'. I waited a good 30 minutes before the interview I had set up through an Armidale council employee, could take place. Eventually Costa and I sat down together in the shade - I had worn no hat and was visibly burnt - and chatted for about 10 minutes about biodiversity. It was rewarding, and now I will write a story for a magazine about the experience.