Horticulture: Can you dig it?

The Chelsea Flower Show, for all its indisputable merits, is not cool. Manicured lawns, panama hats and nicely-trimmed clematis all have their place, but do they really express what it is to be a trowel-wielding, window-sill potting, urban green-fingers in 2012?

London's gardeners have decided not. For the first time this year, in the spirit of the Edinburgh Fringe, a Chelsea Fringe will take place alongside the 99-year-old Royal Horticultural Society (RHS) show. Nearly 90 free events and installations will spring up all over the capital from Saturday – from herb gardens in Battersea to edible flowers in the East End. For three weeks, ordinary people are invited to share in the joy of gardening with a programme that is entirely volunteer-run, open access and, whisper it, a little slightly more down with the kids than your average horticultural festival.

In Dalston, events are being held in an urban garden tucked behind railway hoardings, where pizzas topped with freshly-picked rocket will be baked in a clay oven. In an abandoned building opposite Smithfield Market, 2,000 individual mint plants will liven up the bare brick and plasterboard to create a "Garden of Disorientation", while a bar serves up four different flavours of mojito. Tea and cake in a floral dress this ain't.

It is all the brainchild of journalist and former comedian and actor Tim Richardson, who trod the boards at the Edinburgh Fringe in his youth. The idea of bringing the Fringe principle – a looser, more radical and accessible appendage to an established event – to the flower show, sprang into his head fully formed one morning two years ago.

"I love gardens, so I love the Chelsea Flower Show and I want the Fringe to complement it," he said ahead of tomorrow's launch, dispelling any fears among RHS grandees that there might be an iconoclastic rebel at their gates. "But we are going to take people out of their comfort zone. I'm interested in a new generation of people gardening as an act of community activism, getting to know their neighbours."

That ethos will run through the show. The Dalston Flower Show, an associated event will bring gardening experts into local inner-city schools, and young people from some of London's poorest areas are being invited to discover a love of the soil in the Eastern Curve Garden, an extraordinary, hipster Eden planted over an abandoned railway line that will be a hub of Chelsea Fringe activity.

Fringe organisers hope to inspire an outbreak of something known as "guerrilla gardening", the illicit planting of flowers in unexpected places – the middle of roundabouts, patches of unclaimed land on inner-city estates, by the sides of roads – that can, occasionally, look a touch post- apocalyptic.

"We hope that this place will be a revelation to people," said Marie Murray, who tends the Eastern Curve Garden, which was created two years ago. "The No 1 reason for this garden was to be a breathing space which would allow children and adults to connect with nature. Tending a public garden teaches independence and civic pride – it is amazing the effect it has on people."

Back in the Garden of Disorientation, landscape designer Deborah Nagan is arranging mint in interesting places, transforming a bare, abandoned shell of a building into a dreamy, green cavern that smells absolutely marvellous. From Saturday the installation and accompanying bar will be open to the public as the Chelsea Fringe springs to life.