Teens aren’t just hot in Hollywood.

Broadway, too, has discovered the Jonas Brothers demo, as producers plot to lure tween auds, and depictions of adolescent angst gain artistic cred, thanks in part to 2007 Tony winner “Spring Awakening.”

For the new musical “13,” it’s all teens all the time. Although the rock tuner was conceived and composed by an adult — Jason Robert Brown, whose resume includes such sophisticated legit offerings as “Parade” and “The Last Five Years” — the production’s entire cast and orchestra is made up of performers who range in age from 13 to 17. (Under New York state law, those teen cast members can perform with a valid work permit.)

Naturally, the production aims to attract younger auds with an aggressive marketing push via Facebook, MySpace and text messaging.

While Broadway usually tries to rejuvenate its old-fogey demo with new blood, “13” has a twist: It must convince adults that the show has something in it for them, too.

The plot centers on a soon-to-be 13-year-old New Yorker who finds himself uprooted to Indiana, where he becomes enmeshed in the universal teen dramas of peer acceptance, party invitations and kissing with tongue.

The budget is moderate by Broadway tuner standards but hefty for a show with no known brand name or marquee talent. And as an original musical with a cast of unknown youngsters, the $8 million production needs as much support from kids and adults as it can get.

“It’s a bifurcated audience,” says Bob Boyett, who heads a producing team that includes Roger Berlind, Tim Levy, Ken Davenport and Los Angeles’ Center Theater Group. “Obviously we hope for a traditional audience of adults who regularly go to theater, but we also know this show will attract a large number of young people.”

To draw the younger crowd, producers are aiming to connect with teens through an expanding viral outreach, overseen by Davenport (“Altar Boyz”) and Gotham-based agency Mammoth Advertising.

In addition to a main Web page for the show, there is 13fans.com, where young enthusiasts can hear music, watch videos, interact with cast and creatives and, of course, register contact info so marketers can continue to keep them in their sights.

The online effort was kicked off through a couple of nonstandard events, including an invited dress rehearsal performed in front of an audience composed entirely of teenagers. “We sent a thousand teenagers out into the world that were excited about the show,” Davenport says.

In addition, producers made the unusual move of releasing a cast recording before opening, allowing the music itself to have a viral presence. Just days after its release, the album went to No. 2 on the iTunes soundtrack chart and No. 38 overall.

Of course, the marketing approach also must take into account the fact that most members of this young demo have to rely on Mom and Dad to make the ticket purchase. “We needed to develop the ‘tug-on-Mom’s-coat’ factor,” Davenport says. “There’s nothing more influential than a child who wants something.”

Further initiatives pitched toward teens include an audience-reward system of points that can be redeemed for prizes such as a backstage tour. Producers also have plans for an elaborate texting campaign.

“We’re going to be the first show on Broadway to say ‘turn on your cell phones’ at the start of intermission,” Boyett says. “We want these kids texting all their friends.”

Meanwhile, advertising is reaching traditional audiences through the more standard routes, including print ads, mailing lists and email blasts.

Efforts were made to make the subject matter of the show as universal as possible.

“Our goal creatively was that we expand this show to include the passages we all go through in life — losing friends and gaining friends,” Boyett says.

Brown adds, “There’s something about the struggle to accept yourself that I don’t think is specific to being 13.”

Brown conceived “13” as a young-adult novel to be paired with a companion musical. Although that project never materialized, the composer held on to the idea and made it the basis for the new tuner, which has a book by Dan Elish and Robert Horn.

(Coming full circle, a novelization of “13” penned by Brown and Elish hit bookstores earlier this year.)

The musical preemed at CTG during the 2006-07 season. After several creative changes (including helmer Jeremy Sams replacing Todd Graff), the show played Goodspeed Musicals in Connecticut in May before it began Broadway previews Sept. 16.

Producers are placing prime importance on word of mouth to sell the show to both sectors of its potential aud. But words from a teen’s mouth may prove even more powerful than the words of an adult.

“It’s not just the frequency of communication, but it’s also the intensity,” Davenport says of teens. “When they love something, they lovesomething.”