FTP for large files

[eluser]SeeleyBoothe[/eluser]
I have a plan to be able to take a directory from a website I build and zip it up and then ftp it to a off-site server for backup purposes.

My question is running codeigniters ftp class from a php controller how large can the folder be?

The reason I ask is that the directory is of images and could easily reach 1 gig in size, so I am worried about codeigniter not be able to zip the directory and ftp to the other server.

Any ideas?