It was sung in the science fiction movie "Silent Running" (1972) starring Bruce Dern. Here's a full synopsis of the movie (warning: spoiler alert!).

CLICKY.

The "film's theme song" was, of course, Joan Baez singing "Whose Garden Was This?"

At the end of the movie, I don't think there was a dry eye in the theater.

Good movie! It's available on DVD.

Don Firth