Wanted: Weird, imaginative and quirky.

PortFringe, Portland newest theater festival that celebrates all things edgy, is back for its fourth season June 20-28 with more plays, a bigger schedule and audiences that are expected to swell so much that the festival may soon belie its name.

The fringe festival is becoming mainstream.

Now in its fourth year, PortFringe celebrates edgy and experimental performance arts, and encourages artists to take chances with new work that might be out of place in traditional theater. That petri dish approach, which follows an international model begun in Scotland after World War II, has spawned plays that have been restaged elsewhere and collaborations among artists that have resulted in new theater companies.

The festival begins June 20 on five stages within a few downtown blocks, and includes more than 50 shows over 10 days. This year, Portland Stage Company serves as the hub, with performances on its main stage and Studio Theater, as well as its street-front theater for kids. Other venues are Empire and Geno’s Rock Club. All plays are 60 minutes or less.

“The freedom of being able to mount a show with minimal logistical barriers allows artists to focus on what really matters – the performance and the process – and I think that’s led to creative blossoming at all levels of Maine’s theater community,” said Deirdre Fulton, PortFringe co-founder and one of its organizers.

Keith Powell Beyland, artistic director for Dramatic Repertory Company in Portland, said PortFringe has helped lower the barrier between performer and performance and widened the community of theater artists working together.

The result is new work. Both MTWTFSS’s “Mr. Marmalade” and Tim Ferrell’s “The Boston Trial of a Book Named Naked Lunch” originated at PortFringe and received return engagements at Mad Horse Theatre Company. Ellipsis Productions, a pop-up theater company based in Portland, grew out of PortFringe.

The idea of Fringe is to give people time and space to see what magic happens, Beyland said. Something always does.

“The first few festivals were heavily populated by local talent, and there was a kind of cross-pollination between groups that was really great,” he said. “As more and more out-of-town acts are part of the festivities, I am curious and interested how the growth of PortFringe will amplify in the community at large. Certainly, new ideas and new work is going to be coming into our community – and that is healthy, if not necessary, for any group to grow and mature.”

PortFringe chooses its plays by lottery. Artists submit ideas, and winners are chosen by chance. The first year, about 40 acts presented shows over five days. It’s grown to more than 50 over 10 days. The audience has grown, as well, from about 1,200 tickets sold in 2012 to more than 2,500 last year. If the growth continues, ticket sales could top 3,000 this year.

A comedian and writing coach, Ferrell got involved in PortFringe because he had an idea for a play about obscenities. The casual nature of the festival and its support of works-in-progress appealed to Ferrell, who teaches comedy but had never written a play.

The idea of mounting a play was daunting. Renting a theater and selling tickets takes time and money, and distracts from the creative process. PortFringe made it easy to concentrate on the work, Ferrell said.

He put a cast together, and the festival produced the show last year. The play was a talker, prompting Mad Horse artistic director Christine Louise Marshall to schedule it as a special event this past winter. “I saw ‘The Boston Trial’ at Fringe, and I wanted to see it again – I wanted to see it again, and I wanted other people to see it,” Marshall said.

Ferrell is in the process of publishing the play, and hopes to launch it on the festival circuit. Meanwhile, he’s back with a new show for this year’s Fringe, a political comedy called “Executive Order 1612.” It’s set in the not-too-distant future and involves the youngest elected U.S. president, who is trapped in a nine-week government shutdown. An Independent, the president sequesters himself and his staff and tries to set a record for the most executive orders ever issued.

Ferrell doesn’t act in the show. He’s the writer and director, as he was with “The Boston Trial.”

Writing for the festival has sharpened Ferrell’s storytelling skills, he said. The one-hour time limit forces him to focus on telling the story succinctly and with purpose, he said. “The discipline of telling your story in an hour is really fascinating to me,” he said.

JJ Peeler, a social media and marketing associate at Portland Stage, said the theater’s involvement reflects the growth and appeal of PortFringe. As the festival hub, Portland Stage will serve as a box office and information center, as well as a gathering spot for attendees and actors.

PortFringe is part of a larger fringe festival movement that began in 1947 when a group in Scotland decided to stage an alternative to the Edinburgh International Festival. A local journalist gave it the “fringe” name, and it stuck.

Hundreds of festivals are produced across the world today. The goal is to present edgy, rapid-fire theater at affordable prices.

For PortFringe, single tickets cost $10, but festival organizers encourage people to buy passes, which range from three shows for $28 to an unlimited pass for $125. This year, PortFringe is offering a grab bag of tickets, which includes tickets to random shows chosen by the festival staff for $20.

Beyland, the artistic director at DRC, said the festival serves as a reminder that people are interested in different kinds of theater.

“We should never take ourselves too seriously,” he said. “Theater comes in all shapes and sizes, and there can be extreme magic in a show with two chairs and a bare light bulb. Fringe is about stripping storytelling down to its essence, and also experiencing the depth and breadth of what theater and storytelling in all modes can be.”