Finding folders that contain changed files since date

"find . -type d -newermt '7/15/09'

From the find man page:

-newerXY file

True if the current file has a more recent last access time
(X=a), inode creation time (X=B), change time (X=c), or modification time (X=m) than the last access time (Y=a), inode creation
time (Y=B), change time (Y=c), or modification time (Y=m) of
file. In addition, if Y=t, then file is instead interpreted as a
direct date specification of the form understood by cvs(1). Note
that -newermm is equivalent to -newer."