Featuring Maynard James Keenan and Eric Glomski. Rating not available. Opens Friday, March 12, at the Rio Theatre

If you want to know what it takes to start your own vineyard, Blood Into Wine has a lot for you. If you want to learn about subcultural rock star Maynard James Keenan, frontman of Tool and a couple other bands, keep searching.

The subjects are linked in this highly entertaining documentary because Keenan gradually switched some of his attention to growing grapes. And he did this in remote Jerome, a one-time mining town in Northern Arizona. The area is known for chalky, volcanic terraces that do not resemble Sonoma’s grape-friendly terrain but do bear some resemblance to the arid Greco-Roman places where winemaking got started.

The shaven-headed rocker was assisted in this unlikely venture by Eric Glomski, a former scientist who got caught up in the romance of the vine. The latter has a clever way with words and a warm presence on camera, and that’s handy, because Keenan is, self-admittedly, “not much of a people person”—something filmmakers Ryan Page and Christopher Pomerenke attempt to play with this by pairing their star with people intended to either soften him up or rub him the wrong way.

Chats with pals Patton Oswalt and Milla Jovovich go okay, and there are fun visits from various experts and enologists. (Crusty Arizona tour guide Marshall Trimble is a delightful asset as the narrator.) But the film is occasionally derailed by pieces of an excruciatingly unfunny visit with faux-talk-show hosts Tim Heidecker and Eric Wareheim, used as wholly unnecessary connecting bits.

It’s a mystery why so little of Keenan’s music or personal back story is included, especially since much of Blood Into Wine seems like an advertisement for the guy and his hobby. Still, a lot of what’s here is pretty tasty.