How to ftp a daily ftp folder via script

I need a script. It needs to log onto an SFTP site and copy a daily directory with the previous dates name. My dir structure on my source is "source folder\ 8_7_2014\filenames. Everyday a new folder is created by another task and once that is created I need to ftp the previous days folder to its destination. My FTP client can sync the files however I need to push only one day at a time (the previous dates folder).  I need script that will distinguish only yesterdays date. Help VB or powershell of shell