YOU SAID:
heard it on the grapevine
INTO JAPANESE
ブドウにそれを聞いた
BACK INTO ENGLISH
I heard it in grapes
INTO JAPANESE
私はブドウでそれを聞いた
BACK INTO ENGLISH
I heard it at grapes
INTO JAPANESE
私はブドウでそれを聞いた
BACK INTO ENGLISH
I heard it at grapes
That didn't even make that much sense in English.