Stars Jennifer Garner, Joel Edgerton, and CJ Adams; Directed and written by Peter Hedges, from a story by Ahmet Zappa. Rated PG. 105 minutes. Critic’s grade: C

Remember the Lyle Lovett song that goes, “She wasn’t good, but she had good intentions”?

That sentiment comes to mind with “The Odd Life of Timothy Green,” a fanciful, family-oriented comic drama that’s the third film from Peter Hedges; he fared better with a roomful of sympathetic and well-played characters in 2003’s Steve Carrell vehicle, “Dan in Real Life.”

The good intentions: Hedges built his script on a sweet story, penned by Ahmet Zappa (the less-famous son of Frank Zappa), concerning a childless couple’s encounter with a young boy (CJ Adams, who had a small part in “Dan in Real Life”) who magically springs from the earth, borne both of mystical elements and his new “parents”‘ list of qualities they desired their offspring to possess.

The “wasn’t good” part: The entire movie is bathed in the saccharine sentimentality that fails to cover up its flaws, including a truncated set-up, a low level of chemistry between Jennifer Garner and Joel Edgerton (“Warrior,” “Animal Kingdom”), as the baby-pining Cindy and Jim Green, and the filmmaker’s penchant for practically throwing away potent story conflicts, like the Greens’ efforts to explain the sudden appearance of Timothy. Not to mention the often trite dialogue, and the unsatisfying participation of such acting talent as David Morse, Dianne Wiest, and M. Emmet Walsh, all of whom gamely take on one-note, underwritten roles.

The setting is small-town Stanleyville, an all-American looking burg — Georgia passing for the Midwest — where life is largely lived in the permanently gorgeous hues of late afternoon fall. Those bright autumnal colors provide the backdrop for the unhurried comings and goings of a place centered on the Stanley Pencil Factory. Jim toils there, working for arrogant, self-centered Franklin Crudstaff (Ron Livingston). Cindy spends her days at the factory-affiliated museum, where her cold and officious boss, Franklin’s mom (Wiest), naturally shares some unattractive qualities with Jim’s boss.

One dark and stormy night — literally — Timothy bursts from the earth, and, covered in mud, his legs adorned with leaves that seem to be permanently attached, he shows up inside their home, declaring, “I got here last night. I come from the garden.” Even creepier, the 10-year-old calls his new hosts “Mom” and “Dad.” Good thing mom and dad never watched “Children of the Corn.”

What might have played as a horror-movie sequence in another film (which, coincidentally, takes place in the house where “Halloween II” was shot) barely seems to spook the Greens. They quickly get Timothy cleaned up and tucked in bed, and make plans to enroll him in school and sign him up for the soccer team.

Before launching his career as a director, Hedges penned the terrific, full-bodied screenplays for “About a Boy” and “What’s Eating Gilbert Grape.” So it has to count as somewhat puzzling that he fills out the bulk of “Timothy Green” with mostly uninteresting doings set on the soccer field (hop-hop star Common plays the exasperated coach), at the factory, at the museum, and at the Greens’ home. Sibling rivalry, and father-son issues, figure into things, as does something akin to young love, and a meanie or two get their comeuppances.

The film, too, is lined with a few predictable, and rather routinely rolled out big themes, centered on acceptance of the “different,” and the desirability of unconditional love not poisoned by possessiveness. There’s also the clear positioning of CJ, his arms often outstretched to absorb the sun, as a sort of Christ figure, someone who lives and dies for the sole purpose of redeeming those who love him.

Yes, potentially provocative themes all – too bad they’re wrapped in the rather bland plot machinations of “Timothy Green.”