Python has a standard library module ftplib to run FTP communications. It has two means of getting a listing of directory contents. One, FTP.nlst()
Unfortunately FTP doesn't have a command to list just folders so parsing the results you get from ftp.dir() would be 'best'.
A simple app assuming a standard result from ls (not a windows ftp)
from ftplib import FTP
ftp = FTP(host, user, passwd)
for r in ftp.dir():
if r.upper().startswith('D'):
print r[58:] # Starting point
Standard FTP Commands
Custom FTP Commands