A "willow garden" can be any back property (behind a house or not) that has even a single willow in it. My guess: the willow garden was a piece of low land by a river, where willows grew. Benches were often placed in such spots for courting couples. Good place for concealment, if they were weeping willows, for the descending branches hide kisses and more. Rose Connally ought to have known, though, that kissing under a willow could be bad luck, since willows have signified sadness for centuries ...

As to origins, I seriously doubt any relationship with "Down by the Salley Gardens," apart from the fact that both are Irish in origin (maybe; see below). Just a chance resemblance of phrase, in my opinion.

The song is more usually known as "Rose Connolly," but G.B. Grayson recorded it in 1927 (and Mainer's Mountaineers covered it in 1937) as "Down in the Willow Garden," so that name has stuck.

It's probably a broadside. So far as I know its earliest known occurrence is the Grayson and Whitter recording. Its origin may be British but evidence is missing.

DT discussions of the song appear in the following thread among others:

http://www.mudcat.org/thread.cfm?threadid=14897

Surprisingly, Olive Woolley Burt, in her American Murder Ballads (Oxford 1958) does not include this. Cox adds nothing; nor does Gus Meade in "Country Music Sources" find any original sources, so its origin is still clouded. The Lomaxes, in Folk Song USA (1947) give no specifics, only remarking that it's a song young lady folksingers in New York City seem to cherish. So the usual run of folklorists have come up with a whole lotta nothin'.

Brown, in North Carolina Folklore, Vol II, The Folk Ballads, a usually reliable source on these things, thinks it could be Irish. He says of "Rose Connolly": "One supposes that it is an Irish stall ballad, but I have found it reported only from the United States. Cox ... prints two versions from West Virginia ... in which the murderer names himself (Patsey O'Reilly in A, Morison in B). Shearin and Combs's syllabus lists it for Kentucky ... entitled "Rose Colalee (Colleen?)." He goes on to say it's also reported from North Carolina and Virginia.

It would be worth checking the various broadside ballad collections, starting with the Bodleian, in hopes of coming up with an original somewhere.

Final note: Wayne Erbsen, in Rural Roots of Bluegrass Songs, says Charlie Monroe said his mother used to sing this to him when he was a kid. Zeke Morris disagreed angrily, said Monroe got the song from him. Wade Mainer said "I really don't know where the old song came from."

But my bet is, they all learned it from the remarkable 1920s blind fiddler-singer G.B. Grayson. And to the best of my knowledge Grayson, who had quite a repertoire of odd old songs both folk and pop, never told anyone where he learned it.

Bob