You would have to be tripping somewhere way off the grid not to be aware that this is the 50th anniversary of the Summer of Love, the hippie phenomenon that made San Francisco’s Haight Ashbury ground zero for the emerging counterculture in 1967.

In celebration of that mind-bending moment in time, the Fine Arts Museums of San Francisco threw their considerable resources into the de Young’s “The Summer of Love Experience: Art, Fashion and Rock & Roll,” an exhaustive exhibit of more than 400 cultural artifacts from the flower child era — concert posters, photographs, light shows, psychedelic music and enough hippie regalia to outfit a dozen road companies of “Hair.”

“The Sumer of Love Experience,” which runs through Aug. 20, is the unofficial centerpiece of the many citywide celebrations and events that the California Historical Society conveniently lists online at summerof.love.

Counterculture celebrities came from near and far to attend the preview party my wife and I attended before last Saturday’s opening at the de Young. It felt like a gathering of what is left of the tribes that converged on Golden Gate Park for the Human Be-in a half century ago.

“A lot of people like myself are fat, bald, white-haired, whatever,” joked Peter Albin, bass player for Big Brother and the Holding Company, the band that launched Janis Joplin. “I’d look at someone and think, is that so-and-so?”

I asked Albin what Janis would have thought of this exhibit had she not overdosed in that L.A. hotel room all those years ago.

“She would probably dig the focus on the clothing,” he says. “She was involved in that. She had her own seamstress.”

One of her seamstresses was Linda Gravenites, who has a number of her hippie chic creations in the show, including a suede cape with leather appliques and hand lacing she made for Bill “Sweet Willie Tumbleweed” Fritsch, a leader of the San Francisco Hells Angels in the ’60s.

“After a while Linda couldn’t take the drug scene and left,” Albin says. “It was just after Janis left us and was playing with other bands. There were just too many drugs happening.”

Filmmaker Erik Christensen, director of “The Trips Festival” documentary, introduced me to costume designer Birgitta Bjerke, still tall and vivacious in her 70s. She crocheted a psychedelic bedspread that’s one of the major pieces in the show. It was originally commissioned by Frankie Azzara, girlfriend of the Grateful Dead’s Bob Weir. One panel is an interpretation of the Dead’s rose motif and another features an ace of spades, a nod to Weir’s 1972 solo album, “Ace.” As it happened, Weir never got to see the thing. He and Azzara broke up before it was finished.

I said a quick hello to Woodacre poster artist Victor Moscoso, who has a number of his rock posters in the show for bands like Quicksilver Messenger Service, Steve Miller and the Doors. So does fellow poster artist Stanley “Mouse” Miller, who posed for photos alongside the iconic skull and roses poster he and the late Alton Kelley designed for a Grateful Dead show at the Avalon Ballroom.

Big Brother drummer Dave Getz of Fairfax and his wife, jazz singer Joan Getz, were hobnobbing in a room devoted to black light posters. In that surreal psychedelic atmosphere, high-tech rocker Roger McNamee chatted with cosmic clown Wavy Gravy, who was being pushed in a wheelchair by his wife, Jahanara Romney. She made Wavy’s vintage “rainbow jumpsuit,” prominently displayed on a shelf high above the crowd. Wavy shot me a look when I asked him if it still fits him.

I met photographer Herb Greene, who took many of the classic photos in the exhibit, including the cover shot of the Jefferson Airplane for the band’s 1967 breakout album, “Surrealistic Pillow.” Still looking hip in a retro leather jacket with fringes, Greene came to the show from his home in Massachusetts, where he’s lived for the past 17 years. He he’d move back to the Bay Area, he tells me, “but I can’t afford to live here.”

Another Summer of Love photographer, Elaine Mayes, also came from the East Coast for the exhibit. Elaine lives in a small town in New York’s Catskill Mountains. But, in 1967, she was staying in a house on Mount Tamalpais in Mill Valley that was later bought by the late photographer Suki Hill. The two women shot many of the existing photos of the Fantasy Fair and Magic Mountain Music Festival in Tam’s Mountain Theater that June. The historic two-day event holds the distinction of being the first outdoor rock festival, preceding Monterey Pop by a couple of weeks.

Mayes told me a story about how she had fallen asleep watching TV the evening before the festival and was awakened by a strange man rapping on her window. It turned out to be the South African trumpet star Hugh Masekela, who was on his way to perform at the festival, couldn’t find his way to a friend’s house to crash and ended up sleeping in a bedroll on the ground that night.

“The next day he gave me a ride to the fair on the back of his motorcycle,” she recalls. “That’s how I got there.”

Mayes has her share of Haight Ashbury photos in the de Young show, but she found the exhibit itself a bit unsettling.

“It’s very strange to have that experience encapsulated in a museum,” she says. “There are bits and pieces from that time period that are enshrined, so it’s not alive. It’s completely not like it was then. I had to divorce my mind from the actual events and just look at it as an exhibit in a museum and appreciate it that way.”

If you’re going to San Francisco

What: “The Summer of Love Experience: Art, Fashion and Rock & Roll”

Where: de Young Museum, 50 Hagiwara Tea Garden Drive, San Francisco

When: Through Aug. 20, 9:30 a.m. to 5:15 p.m. Tuesdays through Sundays

Admission: $10 to $25

Information: deyoung.fam.org/visit