By Aarik Danielsen

Each year, the Roots ’N Blues ’N BBQ Festival leaves no doubt why its headliners are headliners. Past closers like Buddy Guy, The John Cowan Band and The Blind Boys of Alabama have sent crowds home satisfied. This year’s ultimate performers, acts like Derek Trucks and Susan Tedeschi, Dan Tyminski, Del McCoury Band and Tab Benoit, should do their forerunners proud with similarly strong, bring-down-the-house-and-start-the-car, last-call sets.

But the strength of a festival is not top-down but start-to-finish. The heights can only be high if there’s been a seamless climb to the top. It’s OK to come for the big-name acts, but come even earlier and enjoy the quality of the bands that come first, artists like these six who shouldn’t be missed.

ANDERS OSBORNE

This Swedish-born songwriter has crafted tunes for Brad Paisley, Tim McGraw, Jonny Lang, Benoit, Jimmy Thackery and others but Osborne’s own records are where his talent truly shines. His work possesses a worldliness cultivated on bon voyages through Africa, Europe, the Middle East and Asia before he settled in New Orleans more than a decade ago. A tremendous vocalist, Osborne’s warm, winsome pipes slide neatly into the grooves he creates on songs that join classic rock, pop, R&B and traditional blues.

Must-hear tunes: “Standing with Angels” and “Meet Me in New Mexico” from the 2010 album, “American Patchwork.”

RON WILLIAMS

The son of country singer Leona Williams and former stepson to Merle Haggard has been a torchbearer both for his family name and the sounds of traditional country music. Influenced by the likes of Haggard, Marty Robbins and Glen Campbell, Williams’ voice harkens back to the glory days of AM country radio. Many notable names have taken notice of the Vienna, Mo., resident — he’s shared the stage with Vern Gosdin, Ferlin Husky, Craig Morgan and Lori Morgan and has written with Joe Diffie.

Must-hear tunes: The title track from the 2004 album “Natural Thing” and “Her Heart Belongs to Texas” from 2009’s “The Longer You’re Gone.”

TRAMPLED UNDER FOOT

Named, ostensibly, for a Led Zeppelin tune, this Kansas City-based family band traffics in a timeless blues-rock style marked by blistering riffs, gutsy vocals and crater-deep grooves. Winners of the 2008 International Blues Challenge and multiple honors from the Pitch Music Awards, each of the three Schneblens is tremendously talented at what they do; bassist Danielle’s vocals are especially revelatory, brassy yet couched in a certain tenderness. From time to time, the band tempers its hard-charging tendencies with equally effective Delta-bred, folk-tinged numbers.

Must-hear tunes: The title track from 2008’s “May I Be Excused” and “Johnny Cheat” from the same record.

HONEY ISLAND SWAMP BAND

Influenced by the music of everyone from Dr. John to Jerry Garcia, the band was formed in the wake of Hurricane Katrina by four displaced New Orleans residents taking shelter in San Francisco. Their 2009 debut, “Wishing Well,” serves up a delicious musical gumbo, flavored by quirky vocals, bursts of brass, blues and bluegrass textures and that patented New Orleans stomp. The record was named 2009’s Best Blues Album by OffBeat Magazine.

Must-hear tunes: “Till the Money’s Gone,” “You Don’t Miss Your Water” and “Sophisticated Momma” from “Wishing Well.”

TAJ WEEKES AND ADOWA

Uniting a “true social consciousness with an unforgettable reggae groove” to “acoustic roots rock and afro-folk simplicity,” the St. Lucia native Weekes and his band creates music that both feels good and encourages listeners to do good. Weekes’ vocals are light and lilting, gliding almost effortlessly over tight grooves and the buoyant sounds of his backing singers.

Must-hear tunes: “Rain Rain” from “A Waterlogged Soul Kitchen,” released this month and “Orphan’s Cry” from 2008’s “Deidem.”

GAROTAS SUECAS

This six-piece São Paulo, Brazil, collective is earning attention from folk enthusiasts and indie rockers. Their sound has been labeled as a blend of Otis Redding and Os Mutantes: Memphis-style horns, soulful organs and psychedelic riffs collide with shuffling Latin rhythms and lyrics sung in their native tongue. The band has played at South by Southwest and received a positive write-up from Sleater-Kinney member/NPR columnist Carrie Brownstein who wrote, “The musicianship in the band far exceeds most groups you’ll witness these days … in the way you’d imagine having your jaw drop at the sight of the Hi Rhythm Band or The Jackson 5 in their heyday.”

Must-hear tunes: “Tudo Bem,” “Alma” and “Mercado Roque Santeiro” from this year’s “Escaldante Banda.”