There are several film adaptations of Frances Hodgson Burnett's beloved children's book, "The Secret Garden," but I can only tell you about two of them. One is a 1975 BBC version, which feels exactly like a 1975 BBC version. Adults might rather like it and appreciate it for its historic, vaguely Masterpiece Theater-feel, but for kids it’s too slow and too musty.
The other version I’m familiar with is the 1993 version, directed by polish director Agnieszka Holland, who has a string of films you’ve never heard of, plus television credits for shows like The Wire and Cold Case. I was surprised not to see another film or two of significance in his bio, as his Secret Garden is absolutely lovely, and the attention given to things like continuity and visual details are admirable.
This film has a G rating, but I doubt it would work on kids under age eight. It’s a pretty sedate, quiet film, the British accents may be a tad difficult for young (American) kids, and there is a dark, brooding melancholy throughout the first half. Younger children would likely have a difficult time with scenes of neglectful parents, dying parents, and “invalid” children throwing temper tantrums (cousin Colin throws a doozy here).
For the older kids, The Secret Garden is a great example of dramatic cinematic storytelling aimed at children that isn’t candy-coated in Disney sugar, and the film’s messages of hope, rebirth, and friendship are heartwarming and very sweet. It’s also mature enough (and lush enough visually) that most parents will enjoy it as well.