Didn't hear that til about 5 or 6 years ago, applied to something that is really nice, and that was from a friend in Gloucestershire, has it spread? bobjugs?
I've known it used in that way (for over 50 years) since I was a child.
The Concise Oxford Dictionary gives the literal meaning as "(Of vegetation, esp. grass) luxuriant and succulent" but it also gives the derived figurative definition as "luxurious".
Perhaps it's just us Suffolk yokels that use it that way?