Grade: C-

n 1962 John Frankenheimer made “Birdman of Alcatraz,” a serious (indeed, overserious) docudrama about long-term inmate Robert Stroud, who finds a sort of redemption by creating a virtual aviary in his cell and gaining world recognition for his ornithological knowledge. Now Joel Hershman, a young American writer-director who got some undeserved praise for his ramshackle debut feature “Hold Me, Thrill Me, Kiss Me” (1992), has made a much lighter, fluffier version of Frankenheimer’s story which could be titled “Bulb-boy of Edgefield.” Though purportedly based on actual event, “Greenfingers”–which the main character at one point quite aptly describes as being about “rehabilitation through gardening”–is structured and written like a formulaic feel-good TV movie. Eager to please and relentlessly good-natured, it will probably amuse relatively undemanding audiences, particularly those composed of elderly women who putter about in the yard themselves. And one can imagine that it might be wildly popular in Britain, where the mania for gardening is one part of that peculiar “There’ll Always Be an England” eccentricity that the New Yorker regularly celebrates. But its artificiality and crushing predictability mark it as a cloying, pedestrian piece of flummery.

The protagonist of the film is Colin (“Croupier” star Clive Owen), a sullen convict who’s transferred to a more progressive prison, Edgefield, whose dog-faced but liberal warden (Warren Clarke, the long-ago Dim in “A Clockwork Orange” and more recently Dalziel in the British cop series) employs unorthodox methods to encourage his prisoners to blossom. In Colin’s case, symmetrically enough, the approach lies in growing flowers, for which he proves to have an astonishing aptitude; soon he, his elderly roommate Fergus Wilks (David Kelly of “Waking Ned Devine,” who doesn’t have to go naked this time around) and three other inmates have created an oasis of loveliness on the institution’s grounds. When the achievement is brought to the attention of well-known gardening authority Georgina Woodhouse (Helen Mirren), she becomes Colin’s patroness, while her mousy daughter Primrose (Natasha Little) becomes a bit more than that. Eventually the fame of the prison garden grows so widespread that the inmate botanists are invited to compete in the royally-sponsored Hampton Court Palace Flower Show; but a series of unhappy circumstances impede their going, and eventually their appearance there comes only after an escape, a death, several confessions and a seemingly foolish sacrifice. The last act, in other words, tries to meld laughter and tears in roughly equal measure, while giving us an unlikely triumph following disappointment: the final “walk to the queen” sequence seems as long as Macy’s Thanksgiving parade, and even more calculated, not to mention smug.

Though it claims to be based on a true story, as so many manipulative telefilms do, everything about “Greenfingers” seems cobbled together from the lazy scriptwriter’s cabinet of cliches. And a talented cast can do little to salvage things. Mirren has some fun playing an “Auntie Mame” sort of oddball, Owen mellows likably, and Kelly milks his frailty for all the sympathy he can, but nothing in their performances rings even faintly true. The other members of the gardening crew–Danny Dyer, Adam Fogerty and Paterson Joseph–are basically caricatures of lovable lugs. Perhaps Clarke exhibits the most appropriate reaction to the circumstances he finds himself in: his face is practically frozen in a smile that seems more like a grimace.

At one point in “Greenfingers,” old Fergus dismisses a design for a rock garden proposed by no less than the Home Secretary (a hapless “Yes Minister” bumbler played by David Lyon) as being “as subtle as a hammering.” Unfortunately, that’s a apt description of the movie, too.