Cali Roots Summer Mix Up pairs reggae legends with up-and-coming acts.

Thousands crowded the lawn in front of the stage. The duo – Lascelle “Wiss” Bulgin and Cecil “Skelly” Spence – seemed to materialize out of the cool night mist, thick with the smell of ocean and ganja.

Even the portion of the audience familiar with Israel Vibration’s music was momentarily stunned to see them walk onto the stage using crutches, the result of devastating childhood polio. But when the music began and Skelly and Wiss started skanking behind their microphones, it was apparent that they come endowed with some serious strength.

“Israel Vibration is about motivation to overcome problems,” Skelly says.

That performance was back at the Monterey Bay Reggaefest in 2009, coincidentally, Cali Roots’ inaugural year.

In just five years, the three-day Cali Roots Festival at the Fairgrounds has grown into the world’s largest reggae-rock gathering on the planet. It’s gotten so big that it’s begun spawning miniature versions of itself on both coasts. Cali Roots: The Carolina Sessions in Wilmington, North Carolina, happens in September. But first, this Saturday, Cali Roots: Back to the Roots erupts at the Fairgrounds with a bill that starts with the roots reggae icons of Israel Vibration, and adds former Black Uhuru member Don Carlos, dancehall guru Yellowman, San Diego reggae rockers Stranger (who also play Casa Sorrento on Friday) and Hawaiian dreadman Mike Love.

Israel Vibration is one of the original roots reggae outfits that helped bring the genre to the American mainstream. By now the Kingston, Jamaica collective has toured worldwide for more than 40 years.

Over the past five years or so, since releasing its Grammy-nominated record Reggae Knights, the group has been touring the globe on a regular basis. Skelly is in his early 60s and Wiss is nearly 60, but they’re not close to retirement. Skelly adds they’ll head into the studio shortly, and fans should expect a new Israel Vibration record before the end of 2015.

Ever since the beginning, when skeptics dismissed the group because of their physical limitations, they found the strength to continue through their faith in Rastafari.

These days they’re also motivated by the opportunity to experience a whole new generation of fans who are coming out to the shows.

“Seeing the younger people show up is fantastic,” Skelly says. “We get to see the music reaching the young people and soothing their soul.”

Skelly and Wiss continue to score Grammy nods: The bona fide soul-soother Reggae Knights is an authentic roots reggae throwback to their breakthrough album, The Same Song. Autobiographical tunes like “Poor and Humble” pays homage to their Kingston upbringing, and “New York City” recounts the duo’s first trip to the Big Apple 25 years ago.

Stranger is one of countless acts that cites Israel Vibration’s brand of roots reggae as a main influence. The outfit’s fearlessness illuminates a willingness to try something new, another cue it takes from Israel Vibration.

Stranger lead singer David Ornelas appeared in May at Cali Roots, but he wasn’t singing – he was live painting, his second such gig.

“Painting and visual arts is my first love, then music,” says Ornelas, who graduated from San Diego State University with a degree in studio arts. “Creating something is all about being human.”

Ornelas uses songwriting as a more immediate outlet for communicating his feelings. His SoCal-based outfit has been at it for more than a decade.

In 2009, the group won Best World Music category at the San Diego Music Awards for its perpetual multi-cultural mash-up of jazz, reggae and everything in between. There are refreshing nuggets like the horn-saturated “Tomorrow Never Comes” off Shelter From the Storm. “Harmonize” glides by on a hovercraft powered by dank dub rhythms that seep deep into your chest.

“I always write from the heart about love or human connection or a protest-like song,” Ornelas explains. “Now that I have more experiences, I feel like I’m ready to say something to the world. I understand how powerful music can be and I try to use it for good, consciousness and observation.”

His passion for fine art extends back to his single-digit years. He was seduced by the vibrancy of Disney animation at an early age, so much so that he sent Walt a letter expressing his dreams of becoming a Disney animator one day, along with a couple of rough Mickey drawings.

“I’m still waiting for a response,” Ornelas jokes.

While Ornelas can’t ignore the visual arts itch, the band that he’s devoted the last 15 years of his life to isn’t going anywhere.

“Performing music is awesome, but with visual arts there’s no wrong chord,” he says. “Doing both at the same time would be something cool.”

Ornelas says he may debut his ambidextrous creative circus act – the frontman would sing in the band while he live paints – during Stranger’s performance Saturday at the Fairgrounds. It’s like he’s echoing an Israel Vibration motif too: Traditional boundaries be damned.

THE SUMMER MIX UP: BACK TO THE ROOTS 3pm (doors 2pm) Saturday, Aug. 9, at Monterey County Fairgrounds, 2004 Fairgrounds Road, Monterey. $35/advance; $40/door. www.summermixup2014.eventbrite.com