Londoners are invited to bring their guitars and learn techniques used by one of Canada's best-known folk icons, Joni Mitchell at a June workshop led by Emm Gryner.

They'll also get a chance to play in arguably one of the largest jam sessions ever held in London, depending on the turnout.

They may even get a chance to see and hear their guitars played on The Grand Theatre stage in October for its run of Joni Mitchell: River, starring Gryner and Canadian stage star Louise Pitre.

The June 5 workshop will explore the unique tunings used by Mitchell in her songs, which included hits such as Help Me, Big Yellow Taxi, Chelsea Morning, Woodstock and Both Sides, Now.

Gryner will be assisted at the workshop by renowned guitarist Greg Lowe, who will handle the musical direction for River.

Lowe and director Allen McInnis will be scouting the audience for guitars to borrow for the run.

"It's not about affording rental guitars, it's about using great guitars that aren't always available for rental," McInnis said.

"We did this in Winnipeg and it was wonderful. We'll see how many show up and how many Greg might be able to use in the show. There's something really cool about having a relationship with people who have great guitars but never have an opportunity to play them in a big setting like this."

You don't have to own an expensive guitar to attend the workshop, just be enthusiast about playing, McInnis said, urging Londoners to bring out their best.

The workshop goal is to teach a variety of what's called 'open' tunings Mitchell used for different songs, often determined by the emotion she was trying to evoke. Open tunings often means tuning the strings so that when you strum the guitar it plays a chord.

McInnis said Mitchell used upwards of 50 different tunings.

The finale will see Gryner and Lowe lead the audience in a massive jam session playing Big Yellow Taxi.