ASA IRONS of the Vermont musical collective Feathers is stroking his beard. It is formidable beard; a biblical beard. He and his band mates — who mainly operate out of a rural farmhouse without cellphones, Internet, manager or booking agent — are at WNYC radio to perform their enigmatic, pixie-ish folk-rock on the long-running show “Spinning on Air.” Today their instruments include a lap harp, a toy xylophone, a Middle Eastern hand drum and an acoustic guitar hand-painted with animals and rainbows.

Ruth Garbus, a dark-eyed 24-year-old whose T-shirt depicts tractors flying through space, is talking about conjuring mystery with music, “that whole psychedelic thing of letting your mind go where it will.” Mr. Irons, 24, his long hair tied up in a bun, chimes in with a story about working as a carpenter and about growing up with parents who were “woods hippies, not town hippies.”

“I’m all about the old world, man,” Mr. Irons says with a mischievous laugh.

Perhaps. But he and his band mates are also about a new world: one of the most creatively vigorous strains of underground music. Initially dubbed “freak folk,” it looked like a trend of the moment a couple of years ago, when two California artists, Joanna Newsom and Devendra Banhart, attracted attention with charmingly shaggy, deceptively whimsical, largely acoustic albums.

But the scene they spearheaded has grown steadily and expanded sonically, getting less folkie and more, well, freaky. It has also gone international. And this season — the Summer of Love 2.0 — it comes into full, wild bloom with releases, tours and festival appearances that promise nothing less than a new age of Aquarius.

The new music is more a mind-set than a genre. It usually employs acoustic instruments, though it’s as likely to have roots in progressive rock, free jazz or Brazilian pop as in Appalachian ballads.

Vocals tend toward the willfully eccentric, arrangements toward the exotic, lyrics toward the oblique. The sound can range from gentle ensemble music befitting a Renaissance fair to electric psychedelia befitting an acid test. The musicians often conjure the 60’s in grooming and countercultural/utopian/back-to-the-land vibe. Many are friends, cultivating a communal network of informal collaboration: they tour together, play on one another’s records and sing one another’s praises. But with a tendency toward art that’s both homespun and solipsistic, and that shows little interest in music industry trappings, they can seem less interested in Making It Big than in keeping it small.

Still, the music is on the rise: for every backwoods group of musicians like Feathers, there are equally beguiling bands like Lavender Diamond, which is based in Los Angeles and engaged a publicity firm before even making a full album. This summer kindred bands like the darkly pastoral Espers, the gorgeously lyrical Vetiver, the raging Comets on Fire, the entrancing Six Organs of Admittance, the boogie-rocking Howlin Rain, the molasses-grooved Brightblack Morning Light, the computer-enhanced Tunng, the improvisatory Wooden Wand and the noisily experimental Grizzly Bear are all releasing CD’s, as are others — Jolie Holland, Ane Brun, Cibelle, Juana Molina and M. Ward — less connected to the scene but reflecting its aesthetics. And that’s not to mention promising artists like Alela Diane (www.myspace.com/alelamusic) who are popping up almost daily on Internet showcases.

These acts mainly play clubs, and their records remain tiny blips on SoundScan. But that may soon change. Virtually every major indie-rock label has embraced the style, including many veteran marketers of punk attitude that would recently have avoided anything vaguely “hippie.” Even Warp, the standard-bearer of British techno, has signed the woodsy Grizzly Bear. And Mr. Banhart is now signed to the hot British XL label, home to the White Stripes and Radiohead’s Thom Yorke.

If the major labels are lagging — well, that’s what major labels do. But with the endless-summer, hippie-folk-lite of Jack Johnson hitting No. 1 on the charts earlier this year, they probably won’t be for long.

Mr. Banhart, who got so much attention in 2004, remains the king of the scene and has extended his reach beyond it. He was recently invited to perform at a Chanel fashion show, to help organize the British alternative-pop festival All Tomorrow’s Parties and to perform at this weekend’s Bonnaroo Festival in Tennessee. He was even romantically linked, for a moment, to the starlet Lindsay Lohan. Along the way the neo-hippie revival he represents is gaining cultural traction. Vice, the magazine, clothing line, record label and all-around hipster franchise, has scheduled psychedelic-rock acts (the veterans Blue Cheer and Roky Erikson, and Boredoms, a Japanese band) among the top acts at the Intonation Festival it sponsors next weekend in Chicago. And “Just Another Diamond Day,” a 1969 song by Vashti Bunyan — an eccentric British singer who’s a folksy patron saint of the new scene — is now playing in a T-Mobile ad.

To make the most of all this interest, archival labels are busy bringing out albums that have been out of print for decades. “We’re living in the age of the reissue,” said Michael Klausman, a buyer for Other Music in New York, a store that is a major source of experimental folk. “For some of the younger musicians, these old records are their formative influences. You see them engaging with the music of their parents’ generation almost like it’s a contemporary phenomena.”

This summer’s version of freak folk tends to be darker and more experimental than first-wavers like Mr. Banhart and Ms. Newsom. The guitarist Ben Chasny is a Northern Californian whose pleasantly droning electro-acoustic recordings date back to the late 90’s. He appears on three impressive new records this season: “The Sun Awakens,” a haunting mix of fingerpicking and feedback by his main creative vehicle, Six Organs of Admittance (who perform at the Mercury Lounge in New York on July 6); “Black Ships Ate the Sky,” an “apocalyptic folk” song-cycle by the former industrial rockers Current 93; and “Avatar,” a ferocious psych-rock set by Comets on Fire (out Aug. 9).

Mr. Chasny, like many musicians on the scene, is a self-confessed record geek. “The whole thing for me at first was getting the beautiful, mysterious record that made you wonder, ‘Who are these guys?’ But then I’d mail-order these crazy psychedelic folk records and feel, ‘Well, that wasn’t really crazy enough.’ So I started making the records I wanted to hear.”

Mr. Chasny’s work with Comets on Fire of Santa Cruz represents the noisier side of new psychedelia, as does the self-titled debut by Howlin Rain, a side project of the Comets’ guitarist Ethan Miller. Their screaming guitars are worlds away from the laid-back sound of most modern “hippie rock.”

“I come from the biggest hippie area in the world,” said Mr. Chasny, who grew up in Arcata, Calif. “But they don’t listen to the real hippie music. They listen to Phish and that groove stuff. I love the old psychedelic music because it wasn’t just imagery.”

“It was music that meant something,” he added.

Precisely what the music meant then, and means now, is an open question. “It’s a very Aquarian thing,” explained Jay Babcock, editor in chief of Arthur, a free-distribution music magazine (with articles on progressive politics and herbalism) that has become the central voice of the new scene. “Hallucinogens, rock ‘n’ roll, love of nature, interest in social justice. These are all people basically fleeing in horror from the homogenizing, materialist, bottom-line corporate monoculture that’s overtaking America.”

Greg Weeks of the Philadelphia electro-acoustic group Espers said, “There’s an element in this community that’s tied in to the most valid aspects of the counterculture and learning from the mistakes of the earlier generation.”

For one thing, he notes that “there isn’t so much reckless abandon” with regard to drug use; just alcohol, marijuana and the occasional psychedelic, most say. Politics, meanwhile, tend to be expressed subtly, through the way people live rather than through explicit song lyrics. “You don’t have to have a grand statement,” Mr. Weeks said. “You can just do things in your own little way, put them out there, and if people respond, it’s going to have a chain reaction. And I think that’s kind of what’s happening.”

Nathan Shineywater and Rachael Hughes of Brightblack Morning Light are an example of that. Hailing from Alabama, they have spent the last couple of years living in tents (and a renovated chicken coop) near Lagunitas, Calif. Their group — whose Crystal Totem tour, with Espers, comes to Brooklyn’s Southpaw on Wednesday and the Mercury Lounge on Friday — will release a marvelously hypnotic self-titled CD this week that’s awash in liquid slide guitar and burbling Fender Rhodes progressions.

“Most of the album was written on hikes at Point Reyes National Seashore and is about interacting with the wilderness,” said Mr. Shineywater from a truck stop en route to Joshua Tree, where he, Ms. Hughes and their dog planned to do some camping with friends (including Mr. Babcock).

As he speaks about nature worship and what psilocybin mushrooms “could do for our collective consciousness,” he obviously relishes his role as hippie ambassador. But he and Ms. Hughes are clearly sincere back-to-the-landers: they work with the eco-activist group Earth First! and organize the Quiet Quiet Ocean festival, an annual music event in California. Naturally, their friends Mr. Banhart and Ms. Newsom drop by.

Community building is an important feature of the scene, both in the United States and abroad. Members of Feathers single out the Finnish experimental folk scene for praise, specifically artists like Lau Nau and Islaja and labels like Fonal, and talk of forthcoming collaborations. Juana Molina of Argentina, whose “Son” is one of the year’s top electro-acoustic records, plans to record this month with Mr. Banhart and Andy Cabic of Vetiver (whose new CD, “To Find Me Gone,” showcases some of the new scene’s best songwriting).

Judging from the number of international artists exploring similar sounds, collective consciousness may be at work. Last month the debut CD by a Swedish singer named Ane Brun was released in the United States; its slightly surreal folksiness suggests the influence of Mr. Banhart’s music, though Ms. Brun says she had not heard it. And in England, Adem and Tunng expand on folk influences with electronics. “You may be in a London basement with a laptop and a guitar, but you can make the city your rural area through music,” said Mike Lindsay of Tunng, which will release its second set of clattering fusion music, “Comments of the Inner Chorus,” in the United States in August.

Tunng, like many of the scene’s players abroad, use loops and digital beats more prominently than its stateside counterparts, an impulse that may have to do with electronic music’s larger cultural presence outside America. But the experimental appetite of the new music is inherently broad. “It’s not about genre,” said Cibelle, a São Paolo musician whose recent CD, “The Shine of Dried Electric Leaves,” was partly produced by Mr. Lindsay and features a duet with Mr. Banhart. She says the current movement has much in common with tropicália, the omnivorous Brazilian cultural movement of the late 60’s. (Os Mutantes, the reunited tropicália act, is also touring this summer, performing at Webster Hall on July 21.) “This new state of mind,” she said by phone from London. “Even if musicians don’t know tropicália by that name, they are still making music that way, by intuition, without rules, following their own uniqueness.”

Perhaps that is as good an explanation as any for the new aesthetic, which is not everyone’s cup of herbal tea. Critics and listeners raised on punk’s supposed anti-hippie credo can be suspicious, if not wholly dismissive of the scene, while some 60’s folk fans find the new incarnation too politically disengaged. As one critic wrote in The New Republic, artists like Ms. Newsom and Mr. Banhart “tend to communicate nothing except self-absorption.”

Other old-schoolers, however, are impressed. Neil Young has invited Ms. Newsom to perform with him, and the Black Crowes singer Chris Robinson has been a devoted supporter of the scene. “For me,” he wrote in an e-mail message, “the collection of artists involved in the so-called psych-folk revival serve as a reminder that in the corporate morass of today’s sterile music industry, there are artists unafraid, confident and talented enough to flourish creatively in a homegrown environment.”

And so it seemed last month while watching Feathers perform at Tonic, a New York club known for its openness to the new music. With five singer-songwriters, the members constantly exchanged instruments — clarinet, violin, mandolin, flute and an electric guitar that threatened like an approaching thunderstorm — and sang of searching for a home “in the fields” and “in the air.”

When they finished, they packed up quickly. One needed to be back in Brattleboro by morning for an early shift at the local food co-op; others were visiting friends in Connecticut. But they took time to exchange hugs with members of the audience, leaving a little pixie dust behind before heading back to the woods.