Greensky’s progressive bluegrass is a square peg in a banjo-shaped hole

On the angst-filled psychedelic opening verse of “Windshield” – the first track from its new album, “If Sorrows Swim” – Greensky Bluegrass’s Paul Hoffman drops an “F” bomb, and it’s clear this isn’t your granddaddy’s bluegrass.

Hoffman and his bandmates can pick with the best of them (as illustrated on new songs like “Letter to Seymour”), but Greensky is as much a rock ’n’ roll jam band as it is a bluegrass act. That’s probably due to how Hoffman and his comrades came to the genre living in Kalamazoo, Mich.

“Our guitar player was the only one that was exposed to bluegrass through his dad,” says Hoffman, who took more of a Grateful Dead-style folk-jam route to bluegrass after seeing David Grisman play mandolin with his quintet.

Although Hoffman never attempted the traditional high lonesome singing style, he and his bandmates studied the greats and learned the genre’s standards.

“When it came time to define ourselves and write our own material, it was hard for me to write songs like that,” he says. “As a writer, I needed something more true to my experience or my reaction to experiences around me. We wanted to play music that’s genuine to us. We love bluegrass, too, and we play quite a few of those songs. Our live experience is this balance between those influences and rock ’n’ roll covers and our originals.”

Although the festival staple has benefited from the growing popularity of acoustic music, it falls more closely with Yonder Mountain String Band and the like than the Avetts Brothers or Mumford & Sons.

“There’s a lot happening with what’s considered popular music compared to when I was a teenager – bluegrass and acoustic and the type of music that’s emphasis is on songwriting and not the production value,” Hoffman says. “The Lumineers are a good example. They were acoustic songwriters that became a pop band.”

Hoffman views the rise in folk as a reflection of the popularity of electronic music.

“The two create a need for the other,” he says. “In a time when there’s all this synthetic DJ computer music being produced, it creates this thirst for what’s organic and real.”

Greensky Bluegrass, in fact, reflects borderless genres, which, in turn, reflect the public’s listening habits that are no longer defined by strict categories.

“That’s happened with the music festival,” Hoffman says. “Del McCoury has somehow transcended this audience and done such amazing things for bluegrass.”

Hoffman says McCoury’s success as a crossover act helped pave the way for Greensky.

“If that hadn’t happened, I don’t know if things could be the way they are,” Hoffman says. “We play loud and jam and we play hard. We’re lucky to play a lot of different types of events, having late, headlining slots alongside rock bands and DJs. We played the same time as Lauryn Hill. I love both those environments, and I’m glad we get to do them both. I wouldn’t be happy in either setting alone.”