Where are the Sally Gardens mentioned by W.B. Yeats in a poem?

There aren't any actual gardens named Salley, so nobody really knows for sure. "Salley" or "Sally" might be a corruption of the English Word "sallow," meaning "a tree of the genus Salix" (a willow) - the Word is also very close to the Irish Word for willow, which is saileach. Because of this, it has been suggested that the gardens might be on the banks of the Ballysadare river near Sligo, where they cultivated willows for thatching materials. However, it could be any gardens with willows - or it might have nothing to do with willows at all.