Ah, the Left Bank in spring . . . . A century or more ago, that would have meant Parisian strollers in their finery watching artists at their easels, painting en plein air - outdoors.

This week, Philadelphia sets that scene on its urban ear, offering the same concept, 2010 style. The city's first Art in the Open festival, Wednesday through Saturday, will feature knitting-needle symphonies, tree-wrapping, floating sculptures, and bird-house neighborhoods, along with more traditional artistic expressions.

In this incarnation, artists will be out on both the right and left banks (of the Schuylkill), and strollers are earnestly invited to bear witness - no finery required.

The plein air tradition may have morphed into something delightfully quirky, but its goals remain the same: creating joy and pleasure as artists and spectators come together under the sky.

And therein lies a tale.

Back in 2007, Ed Bronstein, a Philadelphia architect-turned-artist, had experienced his first open-air painting festival, organized by the Wayne Arts Center. And he had fallen in love.

"It was just such a glorious experience that I began envisioning an even larger, grander, more diverse festival," recalls Bronstein, who found himself lost in visions of artists using the richness of Philadelphia's landscape as a framework, and the Schuylkill as a backdrop. He learned all he could from the Wayne event's organizers, who warned him it would be a monumental challenge.

Undaunted, he drafted a news release for a plein air event that did not yet exist. It included dates, format and details, and it outlined events and workshops involving major Philadelphia-area arts institutions. He even began planning lodgings for out-of-town artists.

"It was definitely a little wacky, but I still sent that press release out to several arts friends I thought might take an interest. I didn't know what to expect."

Lo and behold, within weeks he had two equally passionate partners.

Deenah Loeb, executive director of the City Parks Association of Philadelphia and a longtime champion of the city's arts and culture community, did not recognize that the news release wasn't authentic. She was instantly ready to climb on board.

"I've always been interested in how we use and live with our water resources," Loeb says, "and I was certainly intrigued by how we could do that through the arts."

For Mary Salvante, gallery and exhibitions program director at Rowan University Art Gallery in Glassboro, the appeal also was immediate. Her background includes years as a New York studio artist, and, more recently, arts consultancies with the Philadelphia Mural Arts Program and the Main Line Arts Center, among others.

But Salvante's was a cautious voice: "I knew from my own experience that Ed's timetable was way too optimistic and that there was no way he could do this in the fall of 2008, as he had hoped."

Despite the subsequent hours of meetings and proposal-writing, and the passion of the three planners, there was no way the three could have imagined the financial tsunami that hit just as their project was unfolding.

"The low point came when all of our grant applications were denied last year," says Bronstein, who had ample experience in architecture, including work on Baltimore's waterfront and for Philadelphia restaurateur Steve Poses, but none in arts administration. "I had a lot to learn."

It was at that disappointing juncture that the trio realized they'd have to make it happen themselves.

They began seeking assistance through donated services, while soliciting funds. Like-minded friends who could afford to contribute did, and Bronstein, who largely oversaw that challenge, managed to raise and personally donate the $12,500 needed for ancillary costs.

"We got so much encouragement from the local art community that we did feel validated," he said of the others who shared the vision of the festival, with the Schuylkill as its source of inspiration.

Art in the Open Philadelphia became a reality.

Head for the banks of the Schuylkill from Wednesday though Saturday, 9 a.m. to 6 p.m., and here's what you'll find: From the Fairmount Waterworks at the Philadelphia Museum of Art to Bartram's Garden three miles to the south, 36 artists will be at work. Along that route, visitors can pause to watch their progress, or even engage in art projects using materials provided free.

But don't expect to see only painters. One of the most exciting aspects of Art in the Open, its planners say, is the diversity of expression - it's not your grandfather's plein air festival.

The earlier tradition is rooted in the second half of the 19th century, when working in natural light became important to such French Impressionists as Pissarro, Monet, and Renoir.

But today's art world is vastly different, so, along with 14 painters using various techniques, Art in the Open will feature sculptors, digital media artists, and artists who work with sound, or with found objects. All were selected through a juried process, and most hope to interact with the public as they work, rather than just being observed.

Dance and photography, along with mixed media, will be represented on the Schuylkill's banks, reminders that 21st-century art is redefining boundaries and traditions.

Monet and Renoir could never have imagined, for example, a plein air event in which knitting is the artistic focus, with visitors encouraged to join Baltimore artist Laure Drogoul in her "Mobile Musical Knitting" adventure.

Drogoul will invite participants to join a circle, with knitting needles attached to tiny microphones to amplify their clicking. The result, after sound mixing, will be an aural experience highlighting what Drogoul calls the "symphonic expression" of the collective knitting process.

Denise Karabinus Telang of Portland, Maine, will focus on drawings of birds and foliage and the changing light on the riverbank. She herself will be inside a tentlike structure surrounded by bird-feeders, separate from the external world, yet still part of it.

Working from a temporary outdoor digital photo studio, Blaise Tobia of Philadelphia will create "assembled images" - digital panoramas demonstrating just how far the art of photography has come.

"I want to show that beauty is all around us," says Tremain Smith, who spent years as a community organizer in West Philadelphia before returning to art; she now tries to combine art with social concerns.

Her project focuses on found objects along the Schuylkill and the geometry of buildings as seen from the river. "I'm excited about being outside, next to the river, and surrounded by the urban landscape," says Smith, who uses paper, cloth, and rusted metal pieces in her work.

For the Philadelphia team of Jason Austin and Alek Mergold, whose work incorporates architecture, landscape design and installation art, the outdoor project is a chance to examine all three at once. Austin and Mergold will be creating birdhouses inspired by Philadelphia's iconic rowhouses.

"We aim to have the public ponder the life of their fellow urban inhabitants, the birds, and how the functions of aviary habitats - dry, sheltered and well-ventilated spaces - are similar to those of our own," Austin explains.

Nancy Agati, another Philadelphia artist, is interested in the movement of the Schuylkill's water. "I've been particularly captivated by the powerful currents and churning eddies that form at the base of the Waterworks waterfall," says Agati, whose drawings will be made on silk or Tyvek.

She says she hopes to get feedback from passersby - "the direct reaction to my art, so I can understand how I'm communicating to an audience."

She also expressed what so many involved with the festival feel on the practical level: "We can all plan, of course, but ultimately, nature - namely weather conditions - will have some control, too."

Art in the Open will take place rain or shine. Artists may make provisions for shelter, but the hope is that, while winter 2010 was harsh, spring 2010 will turn its kindest face to the banks of the Schuylkill.