Singer/songwriter Fiona Apple [ tickets ] will join Nickel Creek [ tickets ] for several dates in August as the progressive bluegrass outfit makes some of its final appearances before going on extended hiatus.

The singer--who continues to back her 2005 studio album, "Extraordinary Machine"--and the bluegrass trio will launch their collaborative tour Aug. 2 in Baltimore, with Apple and Nickel Creek slated for 13 performances together before the group makes what it's terming a "farewell (for now)" appearance at the Sept. 1 Four Corners Folk Festival in Lyons, CO. Nickel Creek will also play several dates in July, sans Apple. The group's full itinerary is listed below.

According to Apple's website, she and the members of Nickel Creek met several years ago in Los Angeles, and began occasionally working together at the club Largo, sparking a "loose and friendly musical exchange," according to the site.

Fans who see the upcoming shows "will be treated to an expansion of those collaborations developed at Largo," according to a press release, and should expect to hear "anything from pop standards to country classics to modern rock covers." Apple and Nickel Creek will play separate sets during the shows, with the bluegrass trio acting as Apple's back-up band during her set.

Last August, the group announced that, after seven straight years of touring, they plan to part ways indefinitely to focus on individual projects.

Mandolin player Chris Thile is currently on the road with his solo project, Chris Thile & The How to Grow a Band, through late June. The sibling team of guitarist Sean Watkins and violinist Sara Watkins are currently touring with their own group, The Watkins Family Hour. Dates for both acts are listed at Nickel Creek's page, along with the band's live parody of Britney Spears' "Toxic."